If you are going to lecture skeptics on science, it is probably a good practice not to begin with an analogy that gets the most basic physics incorrect (hint: the fact that falling objects of different masses fall at the same rate has been "settled science" since the late 1500s). Also, using the children's book "If you give a mouse a cookie..." as proof of the existence of positive feedback loops will not be very persuasive to practitioners of big-boy physical sciences and other non-post-modernist researchers.
Posts tagged ‘feedback’
Kevin Drum, while sympathetic (as we all are) to the plight of parents of kids with autism, is obviously frustrated that a few people with no science behind them are causing kids to go un-vaccinated. Both he and Megan McArdle suggest some reasons for this. I added this in the comment section:
It all strikes me as part of the general rebellion against reason we see today, alas.
Last week in my class on the late Middle Ages, we learned about the
early origins of witchcraft denunciations. Most denunciations were
initiated by someone who had undergone a tragedy that seemed
inexplicable -- e.g. the death of a loved one due to disease or a crop
failure or, most commonly, the death of a child. It seems to be part of
human nature to seek out something or someone to blame, and in this case
people latched onto the least sympathetic, most marginalized people
around them (often widowed women) and accused them of witchcraft as the
cause for their tragedy.
The parallels, to me, are striking. I think many of the witchcraft accusers had the same
motivation with the Thimerosal crowd, with only the target changing (now drug companies are the
unsympathetic ones). The only real difference is that we have in fact
added a positive feedback to this point of human nature, by creating a
tort system dominated by sympathy over reason, which tends to pay off
on such wild accusations of witchcraft.
Breast implant makers? Burn them! Vaccine manufacturers? Burn them! Obstetricians? Burn them!
Birthday Vladimer Lenin Earth Day. I have a few thoughts for the day:
Sucking the Oxygen Out of the Environmental Movement
Observe today how little of the discussion is about anything other than climate. There are still many environmental issues in the world that can be improved by the application of man's effort and technology -- unfortunately, climate is the least of these but the issue getting the most attention. Consider how the global warming panic has sucked the oxygen out of the environmental movement. Ten years from now, I predict that true environmentalists will be looking back on the hysteria over trace amounts of CO2 in the atmosphere as a huge setback for real environmental progress.
Environmentalism and Socialism
If you attend any Earth Day events today, notice how many of the speeches and presentations and such are anti-corporate, anti-trade, anti-capitalist, anti-wealth screeds, and have little to do with the environment. If you actually go to a live Earth Day event, you will see why the selection of Lenin's birthday was no accident. You will not see this on the network news, because the media is sympathetic to the environmental movement and tends to edit the socialist rants out as PR protection for the environmentalists, knowing that American audiences would lose sympathy for them if they listened to the whole package. (This is mostly an American phenomenon - I have found from my brief travels in Europe that the media there does less such editing, perhaps because they know their audience is more comfortable with socialism).
The Climate Denier Trick
There are a lot of reasons not to be worried about "inaction" on global warming. To justify the enormously expensive cuts in CO2 productions, on the order of 80% as supported by Obama and Clinton, one has to believe every element of a five-step logic chain:
- Mankind is increasing CO2 concentrations in the atmosphere
- Increased atmospheric CO2 causes the world to warm (by some amount, large or small)
- The increases in CO2 from man will cause substantial warming, large enough to be detectable above natural climate variations
- The increases in world temperatures due to man's CO2 will have catastrophic impacts on civilization
- These catastrophic impacts and their costs are larger than the enormous costs, in terms of poverty and lost wealth, from reducing CO2 with current technologies.
Climate alarmists have adopted a rhetorical trick that no one in the media seems willing to call them on. They like to wage the debate over global warming policy on points one and two only, skipping over the rest. Why? Because the science behind numbers one and two are pretty strong. Yes, there are a few folks who will battle them on these points, but even very strong skeptics like myself accept points one and two as proved.
Here are some examples of how this trick works. If, like me, you do not accept steps 3-4-5 in the above logic chain, you will be called a "denier." When asked what a denier means, a climate alarmist will often position this denial as somehow disputing #1 and #2. On the other hand, if one publicly accepts #1 and #2, the alarmist will shout "QED" and then proceed to say that strong action on CO2 is now justified. When an alarmist says that the a consensus exists, he is probably correct on points 1 and 2. But he is absolutely incorrect that a consensus exists on 3-4-5.
Don't believe me? Think back to the early Republican debate, where the moderator asked for a show of hands whether [I can't remember the exact question] man was causing global warming. The implication is that you either have to accept this whole logic chain or not. One can see why Fred Thompson begged to have 90 seconds to explain his position, and why the moderator, presumably in the alarmist camp, denied it to him.
Over the last year or two, skeptics have gotten a lot better at making their argument. Most all of them, like I do, begin their arguments by laying out a logic chain like this and explaining why one can believe that man-made greenhouse gases cause warming without accepting the need for drastic climate action. The result? Alarmists have stopped debating, and/or have declared that the debate is "over." Remember that last great Al Gore climate debate? Neither do I.
The Single Best Reason Not To Be Worried About Climate
I could, and have, in my books and videos, made arguments on many points in 3-4-5 (links at the bottom of the post). In four, no one ever considers the good effects of warming (e.g. on growing seasons and crop yields) and most every other problem is greatly exaggerated, from hurricane formation to sea level rises. And in five, every time someone has tried to put a price on even small reductions in CO2, the numbers are so enormous that they are quickly suppressed by a environmentalist-sympathetic media. Suffice it to say that even the climate-sanctimonious Europeans have not been willing to pay the price for even slowing down their CO2 growth (which has risen faster than in the US), much less reducing it.
But in this logic chain, there is little need to argue about four and five if #3 is wrong. And it is.
The effects of CO2 acting alone on temperatures are quite small -- And everyone, even the alarmists, agree! A doubling of CO2 concentrations, without other effects that we will discuss
in a moment, will heat the earth no more than about 1 degree Celsius (though several studies recently have argued the number is much less). This is not some skeptic's hallucination -- this is
straight out of the IPCC third and fourth assessments [IPCC text quoted here]. In fact, the IPCC in their reports has steadily reduced their estimate of the direct contribution of CO2 on temperatures. CO2, acting
alone, warms the Earth only slowly, and at this rate we would see less
than a degree of warming over the next century, more of a nuisance than
But some scientists do come up with catastrophic warming
forecasts. They do so by assuming that our Earth's climate is
dominated by positive feedbacks that multiply the initial warming from
CO2 by a factor of three, four, five or more. This is a key point -- the
catastrophe does not come from the science of greenhouse gases, but
from separate hypotheses that the earth's climate is dominated by
positive feedback. This is why saying that greenhouse gas
theory is "settled" is irrelevant to the argument about catastrophic
forecasts. Because these positive feedbacks are NOT settled science.
In fact, the IPCC admits it does not even know the sign of
the most important effect (water vapor), much less its magnitude. They
assume that the net effect is positive, and in fact strongly so - on the order of 60-80% feedback or more, nearly unprecedented numbers for a long-term stable physical system [more on feedback and its math here]. This is particularly ironic because alarmist Michael Mann, with his hockey stick, famously posited that temperatures over the last 1000 years were incredibly flat and stable until man started burning fossil fuels, a proposition that is hard to believe if the climate is dominated by strong positive feedback. Note that when people like Al Gore say things like "tipping point," they are in effect hypothesizing that feedback is greater than 100%, meaning that climate can be a runaway process, like nuclear fission.
In fact, with the 100 or so years of measurements we have for temperature and CO2, empirical evidence does not support these high positive feedbacks.
Even if we assign all the 20th century warming to CO2, which is
unlikely, our current warming rates imply close to zero feedback. If
there are other causes for measured 20th century warming other than
CO2, thereby reducing the warming we blame on CO2, then the last
century's experience implies negative rather than positive feedback in
the system. As a result, it should not be surprising that high
feedback-driven forecasts from the 1990 IPCC reports have proven to be
way too high vs. actual experience (something the IPCC has since
However, climate scientists are unwilling to back down from the thin
branch they have crawled out on. Rather than reduce their feedback
assumptions to non-catastrophic levels, they currently hypothesize a
second man-made cooling effect that is masking all this feedback-driven
warming. They claim now that man-made sulfate aerosols and black
carbon are cooling the earth, and when some day these pollutants are
reduced, we will see huge catch-up warming. If anything, this cooling
effect is even less understood than feedback. What we do know is that,
unlike CO2, the effects of these aerosols are short-lived and therefore
localized, making it unlikely they are providing sufficient masking to
make catastrophic forecasts viable. I go into several reality checks
in my videos, but here is a quick one: Nearly all the man-made cooling
aerosols are in the northern hemisphere, meaning that most all the
cooling effect should be there -- but the northern hemisphere has
actually exhibited most of the world's warming over the past 30 years,
while the south has hardly warmed at all.
In sum, to believe catastrophic warming forecasts, one has to believe both of the following:
- The climate is dominated by strong positive feedback, despite
our experience with other stable systems that says this is unlikely and
despite our measurements over the last 100 years that have seen no such
- Substantial warming, of 1C or more, is being masked by aerosols,
despite the fact that aerosols really only have strong presence over
5-10% of the globe and despite the fact that the cooler part of the
world has been the one without the aerosols.
Here's what this means: Man will cause, at most, about a degree of
warming over the next century. Most of this warming will be
concentrated in raising minimum temperatures at night rather than
maximum daytime temperatures (this is why, despite some measured
average warming, the US has not seen an increase of late in maximum
temperature records set). There are many reasons to believe that man's
actual effect will be less than 1 degree, and that whatever effect we
do have will be lost in the natural cyclical variations the climate
experiences, but we are only just now starting to understand.
To keep this relatively short, I have left out all the numbers and
such. To see the graphs and numbers and sources, check out my new climate video, or my longer original video, or download my book for free.
Update: Very relevant article by Roy Spencer on the over-estimation of feedback in climate models.
Many of us, especially those who were trained as meteorologists,
have long questioned the climate research community's reliance on
computerized climate models for global warming projections. In
contrast to our perception that the real climate system is constantly
readjusting to internal fluctuations in ways that stabilize the system,
climate models built upon measured climate behavior invariably suggest
a climate system that is quite sensitive - sometimes catastrophically
sensitive "” to perturbations such as those from anthropogenic
greenhouse gas emissions. Unfortunately, it has been difficult to
articulate our "˜hand-waving' concerns in ways that the modelers would
appreciate, i.e., through equations.
After years of pondering this issue, and after working on our two
latest papers on feedbacks (Spencer et al., 2007; Spencer and Braswell,
2008, hereafter SB08), I believe that I can now explain the main reason
for this dichotomy. Taking the example of clouds in the climate
system, the issue can be introduced in the form of a question:
To what extent are climatic variations in
clouds caused by temperature change (feedback), versus temperature
change being the result of cloud variations?
About two years ago I made the time investment to rip all my CD's to digital (this was a real death-march, at 20 CDs a night for a month). In doing so, I actually ripped every one of them twice: once into a small, variable bit-rate MP3 file for my iPod, and a second time into a much larger FLAC digital file (this is an open-source lossless compression format). All the FLAC files sit on an old computer on my network that does nothing but act as a file server for these music files.
Now, having lots of nice, high quality digital files, the trick is to play them through my home audio system. My first solution was an iPod dock on my home audio system, but I found this awkward. Next, I added a Squeezebox from SlimDevices, a small inexpensive box that hangs on the network that basically takes the digital files off the network and puts then in an analog or digital signal my stereo system knows what to do with. SlimDevices has always been a favorite among audiophiles, because of their open-source approach and their willingness to continue to improve their product with user feedback. And, they are pretty reasonably priced.
Both of these solutions suffered from one problem. My living room is fairly large, and while each system had a remote, the menu screen I was navigating was way over there, either on the small iPod screen or on the larger squeezebox screen. Either way, I still did not like the ergonomics.
In their new version of the Squeezebox, Slimdevices has come out with what I consider the near perfect streaming audio device. The product consists two pieces. First, the audio device, which is pretty small, that hangs on the network (either by cable or wireless) and does the same job as the old boxes I had, converting digital music files to a format my music equipment can handle. The key area of improvement is in the remote control. The remote communicates with your wireless network, and allows one to scroll through his whole music collection right on the remote in an interface nearly identical to the iPod, including album cover art if one so chooses. (click for larger view)
I have had this new Squeezebox for over a month now, and I love it. For those of you with a lot of CDs, like I have, it is just amazing how much more I listen to my music collection with this setup. In the old world of shuffling through CD cases in a rack, I would tend to get the same five or six in a rotation. Now, I listen to much more. The remote also has a headphone jack so it can operate like a portable music player (as long as it is in range of your wireless network).
By the way, I know there are devices like this that are all-in-one, meaning that they have their own hard drive so you don't need to network it to a computer. I find those boxes to be a) way expensive and b) difficult to upgrade. The cost of a cheap computer (it does not need much of a processor to just serve digital files up to the network) with a good size hard drive is cheap, and is the perfect use for an old computer you have upgraded. The only real flaw of this device is its inability to do video, but SlimDevices has always focused on audio and will probably stay that way.
Mixed news on the contest front. My outline and draft novel did not make the finals of the Mackinac Center's Freedom in Fiction Prize.
However, my 3-minute climate video did win second place in the Kids and Globaloney contest.
The results surprise me a bit. I really felt good about my story concept for the fiction prize, so much so I will likely finish it and at least release it as an e-book. On the other hand, I found the 3-minute limit almost impossible to make work in the video contest, and thought my video, which I include below, was rushed.
A better version is the 9-minute version here which covers the same subjects but with a bit more leisure and explanation. This video, however, is a bit dated. As I write in the YouTube comments, I want to take a better shot at explaining the issues around positive feedback. I think I can fix it with just a rewrite of the narration. That longer video is here and below.
My really long video, 60-minutes in 6 parts, is here.
I got to thinking today about regulation and its enforcement in this imperfectly government-dominated world after reading this Jon Stewart quote as relayed by Kevin Drum:
With this administration, if a passenger blows up a plane, it's a
failure in the war on terror. But if the plane just blows up on its own
"” eh, it's the market self-regulating.
What struck me that I had not thought of before is the question of whether non-enforcement of a published regulatory regime was the same as letting a market self-regulate. And my answer was: No, at least not in the short to medium term.
The reason is that the government regulatory regime crowds out private mechanisms that might attempt to achieve the same goals. What do I mean by crowding out? For example, if the government published car reliability metrics and regulation for all cars, no matter how imperfect, would JD Power and Consumer Reports bother with the investment to do the same? For decades, insurance companies wrote de facto building codes and performed fire inspections of their insured structures. They no longer do so, because the government has taken on that role (arguably less well than the insurance companies, who had the reputation of being tigers on such inspections). Would Moody's exist to rank bond risks if the government had regulations in place that theoretically forced all securities to (I don't know how) have the same risk? My marina liability insurer conducts occasional inspections of my marinas.
As a result, insurers don't inspect airlines, nor do manufacturers enforce inspection and replacement regimes (as automobile companies do, to some extent, to protect their warranty). Third parties rate airlines for customer service but not for safety. The whole private evaluation regime for airlines exists on the assumption that the government has regulatory program X and Y in place that is enforced. In the long term, if the government were to abandon enforcement, and this lasted long enough for that expectation to exist in the market, new private regulatory methods would arise [arguments would most certainly exist between libertarians and others whether these new regimes were as effective as the old regime, but almost undoubtedly something would emerge]. But in the near term, we don't have a self-regulating market or even the expectation of one.
As a result, I come to the conclusion that while deregulation may be needed, the absolute wrong way to do it is via non-enforcement of existing regulations. So there you have it, a libertarian calls for better enforcement. Comments? I am just starting to think about this and would appreciate feedback.
Cross-posted from Climate Skeptic. I believe this to be an extremely important issue. Catastrophic global warming forecasts are driven not by greenhouse gas theory, but by the theory that the Earth's climate is dominated by positive feedback. This post discusses these issues:
It is silly to argue whether CO2 in the atmosphere can cause global warming: It clearly does. The issue is not "if" but "how much". The warming from man's CO2 might be 8 degrees in a century, as Al Gore might argue, in which case man's CO2 would be incredibly disruptive. Or it might cause just a few tenths of a degree of warming, which might be unnoticeable within the noise of natural climate variation.
Interestingly, the key to understanding this issue of the amount of warming does not actually lie in greenhouse gas theory. Most scientists, skeptics and alarmists alike, peg the warming directly from CO2 at between 0.3 and 1.0 degrees Celsius for a doubling in CO2 levels (this notion of how much temperatures would increase for a doubling of CO2 levels is called climate sensitivity). If this greenhouse gas warming was the only phenomenon at work, we would expect man-made warming over the next century even using the most dire assumptions to be less than 1C, or about the same amount we have seen (non-catastrophically) over the last century. Warming forecasts of this magnitude would not in any way, shape, or form justify the draconian economic impacts of many current government carbon reduction proposals.
The key, as I have written before (and here), lies not in greenhouse gas theory itself but in the theory that the earth's climate is dominated by positive feedback. This theory hypothesizes that small changes in temperature from greenhouse gas increases would be multiplied 3,4,5 times or more by positive feedback effects, from changes in atmospheric water vapor to changing surface albedo.
Let me emphasize again: The catastrophe results not from greenhouse gas theory, but from the theory of extreme climactic positive feedback. In a large sense, all the debate in the media is about the wrong thing! When was the last time you saw the words "positive feedback" in a media article about climate?
Christopher Monckton has an absolutely dead-on post at Roger Pielke's blog about this feedback theory that I want to excerpt in depth.
This chart is a good place to start. It shows the changes in the IPCC's estimate for climate sensitivity to CO2 and how it has changed over the course of the reports. More importantly, he splits the forecast between the amount due directly to Co2, and the amount due to the multiplicative effect of positive feedback. The green bar is the direct contribution of Co2, and the pink is the feedback.
We can observe a couple of things. First, the IPCC's estimate of the amount of warming due to CO2 directly via the greenhouse gas effect has actually been going down over time. (Note that there are those, like Richard Lindzen, who suggest these numbers are still three times too high given that we have not observed a difference in surface and lower troposphere warming that greenhouse gas theory seems to predict).
Second, you will see that the IPCC's overall forecasts of climate sensitivity have been going up only because their estimates of positive feedback effects have gone way up. The IPCC assumes that feedback effects multiply warming from CO2 by three. And note that the IPCC's forecasts of feedback effects trail those of folks like James Hansen and Al Gore.
So how confident are we in these feedback effects? Well, it turns out we are not even sure of the sign! As Monckton writes:
The feedback factor f accounts for at least two-thirds of all radiative forcing in IPCC (2007); yet it is not expressly quantified, and no "Level Of Scientific Understanding" is assigned either to f or to the two variables b and Îº upon which it is dependent....
Indeed, in IPCC (2007) the stated values for the feedbacks that account for more than two-thirds of humankind's imagined effect on global temperatures are taken from a single paper. The value of the coefficient z in the CO2 forcing equation likewise depends on only one paper. The implicit value of the crucial parameter Îº depends upon only two papers, one of which had been written by a lead author of the chapter in question, and neither of which provides any theoretical or empirical justification for the IPCC's chosen value. The notion that the IPCC has drawn on thousands of published, peer-reviewed papers to support its central estimates for the variables from which climate sensitivity is calculated is not supported by the evidence.
Given the importance of feedback to their forecasts, the treatment in the latest IPCC report of feedback borders on the criminal. I have read the relevant sections and it is nearly impossible to find any kind of discussion of these issues. A cynical mind might describe the thousands of pages of the IPCC report as the magician grabbing your attention with his left hand to hide what is in his right hand. And what is being hidden is that ... there is nothing there! Feedback is the pivotal point on which the whole discussion of drastic carbon abatement should turn and there is nothing there.
Monckton goes further, to point out that hidden in the IPCC numbers lies an absurdity:
if the upper estimates of each of the climate-relevant feedbacks listed in IPCC (2007) are summed, an instability arises. The maxima are -
Water vapor 1.98, lapse rate -0.58, surface albedo 0.34, cloud albedo 1.07, CO2 0.57, total 3.38 W m-2 K-1.
The equation f = (1 - bÎº)-1 becomes unstable as b â†’ Îº-1 = 3.2 W m-2 K-1. Yet, if each of the individual feedbacks imagined by the IPCC is increased to less than the IPCC's maximum, an instability or "runaway greenhouse effect" is reached.
Yet it is reliably inferred from palaeoclimatological data that no "runaway greenhouse effect" has occurred in the half billion years since the Cambrian era, when atmospheric CO2 concentration peaked at almost 20 times today's value
Positive feedback can be weird and unstable. If there is enough of it, processes tend to run away (e.g. nuclear fission), which is what Monckton is arguing that some of the IPCC assumptions lead to. Even when feedback is less positive, it still can cause processes to fluctuate wildly. In fact, it is fairly unusual for long-term stable processes like climate to be dominated by positive feedback. Most scientists, when then meet a new process, would probably assume negative feedback until proven otherwise. This is a particular issue in climate, where folks like Michael Mann have gone out of their way to argue that the world temperature history over the last 1000 years before man began burning fossil fuels is incredibly stable and unchanging. If so, how can this be consistent with strong positive feedback?
Anyway, there is a lot more numerical detail in Monckton's post if you want to dig into the equations.
I would add one thing to his analysis: If you look at the last 100 years of history, the change in temperature given the observed change in CO2 levels comes no where close to a climate sensitivity of 3 or more, even when you assign all historical warming to CO2 rather than other effects like the sun. In fact, as I showed in this analysis, climate sensitivity appears to be 1.2 when one assigns all past warming to CO2, and something well less than that if one accepts the sun and other effects also play a role. These historical analyses would point to feedback that is either zero or negative rather than positive, more in line with what one would expect from complex natural systems.
You can see a discussion of many of these topics in the video below:
The catastrophe that Al Gore and others prophesy as a result of greenhouse
gases is actually not, even by their admission, a direct result of greenhouse
gas emissions. Even the IPCC believes that warming directly resulting from
manmade CO2 emissions is on the order of 1 degree C for a doubling of CO2 levels
in the atmosphere (and many think it to be less).
The catastrophe comes, not from a mere 1 degree of warming, but from the
multiplication for this warming 3,4,5 times or more by hypothesized positive
feedback effects in the climate. Greenhouse gas theory gives us warming
numbers we might not even be able to find amidst the natural variations of our
climate; it is the theory of strong positive climate feedback that gives us the
So, In a large sense, the proposition that we face environmental armageddon
due to CO2 rests not on greenhouse gas theory, which is pretty well understood,
but on the theory that our climate system is dominated by strong positive
feedbacks. This theory of positive feedback is almost never discussed publicly,
in part because it is far shakier and less understood than greenhouse gas
theory. In fact, it is very probable that we have the sign, much less the magnitude,
of major feedback effects wrong. But if we are considering legislation to gut
our economies in order to avoid a hypothesized climate catastrophe, we should be
spending a lot more time putting scrutiny on this theory of positive feedback,
rather than just greenhouse gas theory.
Fans of Toshiba's HD DVD format have been kicked while they're down, this time by Wal-Mart's decision to ditch the format,
and sell Blu-ray players and media exclusively. Effective June, the
move is the result of customer feedback, and an attempt to "simplify"
patron's decisions. This news closely follows Best Buy's decision to
also give the format the boot. Speculation has already surfaced that
suggests Toshiba will abandon their own format "in the coming weeks"...
So file all that HD-DVD software next to your Betamax tapes. I actually preferred the HD-DVD format, but thought from the beginning that Blu-Ray's position in home gaming machines, which immediately gave them a huge installed based before any of us started buying High Def. movie players for our home theaters, might give it a lead that could not be overcome.
Most consumers have just wanted the format wars to be over so they could pick the right player and software (I partially avoided this problem by buying a combo player). This is an interesting consumer-friendly role for Wal-Mart that I have never seen discussed, that of standards-setter.
So here is a message to Blu-Ray: Now that you are on the verge of victory, you need to clean up your own house. The creeping standards problem you have had, which has caused early players to be unable to play newer disks, has got to end. In particular, it is irritating not to be able to play a newer disk because the fancy multimedia menu won't work. When when you learn that we aren't interested in all that crap and just want the movie to start? Just because the technology says you can do that stuff does not mean that you should.
I began with an 85-page book. I shortened that to a 50-minute film, and then a 9-minute film. With that experience, I think I can now pull out and summarize in just a few paragraphs why we should not fear catastrophic global warming. Here goes:
Climate catastrophists often argue that global warming theory is "settled science." And they are right in one respect: We have a pretty good understanding of how CO2 can act as a greenhouse gas and cause the earth to warm. What is well agreed upon, but is not well communicated in the media, is that a doubling of CO2, without other effects that we will discuss in a moment, will heat the earth about 1 degree Celsius (plus or minus a few tenths). This is not some skeptic's hallucination -- this is straight out of the IPCC third and fourth assessments. CO2, acting alone, warms the Earth only slowly, and at this rate we would see less than a degree of warming over the next century, more of a nuisance than a catastrophe.
But some scientists do come up with catastrophic warming forecasts. They do so by assuming that our Earth's climate is dominated by positive feedbacks that multiply the initial warming from CO2 by a factor of three, four, five or more. This is a key point -- the catastrophe does not come from the science of greenhouse gases, but from separate hypotheses that the earth's climate is dominated by positive feedback. This is why saying that greenhouse gas theory is "settled" is irrelevant to the
argument about catastrophic forecasts. Because these positive feedbacks are NOT settled science. In fact, the IPCC admits it does not even know the sign of the most important effect (water vapor), much less its magnitude. They assume that the net effect is positive, but they are on very shaky ground doing so, particularly since having long-term stable systems like climate dominated by positive feedback is a highly improbable.
And, in fact, with the 100 or so years of measurements we have for temperature and CO2, empirical evidence does not support these high positive feedbacks. Even if we assign all the 20th century warming to CO2, which is unlikely, our current warming rates imply close to zero feedback. If there are other causes for measured 20th century warming other than CO2, thereby reducing the warming we blame on CO2, then the last century's experience implies negative rather than positive feedback in the system. As a result, it should not be surprising that high feedback-driven forecasts from the 1990 IPCC reports have proven to be way too high vs. actual experience (something the IPCC has since admitted).
However, climate scientists are unwilling to back down from the thin branch they have crawled out on. Rather than reduce their feedback assumptions to non-catastrophic levels, they currently hypothesize a second man-made cooling effect that is masking all this feedback-driven warming. They claim now that man-made sulfate aerosols and black carbon are cooling the earth, and when some day these pollutants are reduced, we will see huge catch-up warming. If anything, this cooling effect is even less understood than feedback. What we do know is that, unlike CO2, the effects of these aerosols are short-lived and therefore localized, making it unlikely they are providing sufficient masking to make catastrophic forecasts viable. I go into several reality checks in my videos, but here is a quick one: Nearly all the man-made cooling aerosols are in the northern hemisphere, meaning that most all the cooling effect should be there -- but the northern hemisphere has actually exhibited most of the world's warming over the past 30 years, while the south has hardly warmed at all.
In sum, to believe catastrophic warming forecasts, one has to believe both of the following:
- The climate is dominated by strong positive feedback, despite our experience with other stable systems that says this is unlikely and despite our measurements over the last 100 years that have seen no such feedback levels.
- Substantial warming, of 1C or more, is being masked by aerosols, despite the fact that aerosols really only have strong presence over 5-10% of the globe and despite the fact that the cooler part of the world has been the one without the aerosols.
Here's what this means: Man will cause, at most, about a degree of warming over the next century. Most of this warming will be concentrated in raising minimum temperatures at night rather than maximum daytime temperatures (this is why, despite some measured average warming, the US has not seen an increase of late in maximum temperature records set). There are many reasons to believe that man's actual effect will be less than 1 degree, and that whatever effect we do have will be lost in the natural cyclical variations the climate experiences, but we are only just now starting to understand.
To keep this relatively short, I have left out all the numbers and such. To see the graphs and numbers and sources, check out my new climate video, or my longer original video, or download my book for free.
UPDATE: Based on a lot of comment activity to this post at its mirror at Climate Skeptic,
I wanted to add a bit of an update. It is sometimes hard to summarize
without losing important detail, and I think I had that happen here.
Commenters are correct that positive feedback dominated systems can
be stable as long as the feedback percentage is less than 100%. By
trying to get too compact in my arguments, I combined a couple of
things. First, there are many catastrophists that argue that climate
IS in fact dominated by feedback over 100% -- anyone who talks of
"tipping points" is effectively saying this. The argument about
instability making stable processes impossible certainly applies to
these folks' logic. Further, even positive feedback <100% makes a
system highly subject to dramatic variations. But Mann et. al. are
already on the record saying that without man, global temperatures are
unbelievably stable and move in extremely narrow ranges. It is hard
to imagine this to be true in a climate system dominated by positive
feedback, particularly when it is beset all the time with dramatic
perturbations, from volcanoes to the Maunder Minimum.
To some extent, climate catastrophists are in a bind. If historic
temperatures show a lot of variance, then a strong argument can be made
that a large portion of 20th century warming is natural occilation. If
historic temperatures move only in narrow ranges, they have a very
difficult time justifying that the climate is dominated by positive
feedbacks of 60-80%.
The point to remember, though, is that irregardless of likelihood,
the historical temperature record simply does not support assumptions
of feedback much larger than zero. Yes, time delays and lags make a
small difference, but all one has to do is compare current temperatures
to CO2 levels 12-15 years ago to account for this lag and one still
gets absolutely no empirical support for large positive feedbacks.
Remember this when someone says that greenhouse gas theory is
"Settled." It may or may not be, but the catastrophe does not come
directly from greenhouse gasses. Alone, they cause at most nuisance
warming. The catastrophe comes from substantial positive feedback (it
takes 60-80% levels to get climate sensitivities of 3-5C) which is far
from settled science.
After releasing my first climate video, which ran over 50 minutes, I had a lot of feedback that I should aim for shorter, more focused videos. This is my first such effort, setting for myself the artificial limit of 10 minutes, which is the YouTube limit on video length.
While the science of how CO2 and other greenhouse gases cause
warming is fairly well understood, this core process only results in
limited, nuisance levels of global warming. Catastrophic warming
forecasts depend on added elements, particularly the assumption that
the climate is dominated by strong positive feedbacks, where the
science is MUCH weaker. This video explores these issues and explains
why most catastrophic warming forecasts are probably greatly
If you have the bandwidth, you can download a much higher quality version by right-clicking either of the links below:
- 640 x 480 Windows media version, 86MB
- 320 x 240 Windows media version, 31MB
- Quicktime 640 x 480 version, 245MB
I am not sure why the quicktime version is so porky. In addition, the sound is not great in the quicktime version, so use the windows media wmv files if you can. I will try to reprocess it tonight. All of these files for download are much more readable than the YouTube version (memo to self: use larger font next time!)
This is a companion video to the longer and more
comprehensive climate skeptic video "What is Normal -- a Critique of
Catastrophic Man-Made Global Warming Theory."
Over at Climate Skeptic, I dissect climate models to show that the future warming in the models from CO2 alone is not much more than 0.5C. All the catastrophe comes from positive feedbacks that modelers assume dominate the climate, an odd assumption for such a long-term stable system. I summarize as follows:
Climate sensitivity is the temperature increase we might expect with a doubling of CO2 to 560 ppm from a pre-industrial 280ppm
Nearly every forecast you have ever seen assumes the
effect of CO2 alone is about a 1C warming from this doubling. Clearly,
though, you have seen higher forecasts. All of the "extra" warming in
these forecasts come from positive feedback. So a sensitivity of 3C
would be made up of 1C from CO2 directly that is tripled by positive
feedbacks. A sensitivity of 6 or 8 still starts with the same 1C but
has even higher feedbacks
Most thoughtful climate scientists will admit that
we don't know what these feedbacks are -- in so many words, modelers
are essentially guessing. Climate scientists don't even know the sign
(positive or negative) much less the magnitude. In most physical
sciences, upon meeting such an unknown system that has been long-term
stable, scientists will assume neutral to negative feedback. Climate
scientists are the exception -- almost all their models assume strong
Climate scientists point to studies of ice cores and
such that serve as proxies for climate hundreds of thousands of years
ago to justify positive feedbacks. But for the period of history we
have the best data, ie the last 120 years, actual CO2 and measured
temperature changes imply a sensitivity net of feedbacks closer to 1C,
about what a reasonable person would assume from a stable process not
dominated by positive feedbacks.
Kevin Drum links to a blog called Three-Toed Sloth in a post about why our climate future may be even worse than the absurdly cataclysmic forecasts we are getting today in the media. Three-Toed Sloth advertises itself as "Slow Takes from the Canopy of the Reality-Based Community." His post is an absolutely fabulous example how one can write an article where most every line is literally true, but the conclusion can still be dead wrong because one tiny assumption at the beginning of the analysis was incorrect (In this case, "incorrect" may be generous, since the author seems well-versed in the analysis of chaotic systems. A better word might be "purposely fudged to make a political point.")
He begins with this:
climate system contains a lot of feedback loops. This means that the ultimate
response to any perturbation or forcing (say, pumping 20 million years of
accumulated fossil fuels into the air) depends not just on the initial
reaction, but also how much of that gets fed back into the system, which leads
to more change, and so on. Suppose, just for the sake of things being
tractable, that the feedback is linear, and the fraction fed back
is f. Then the total impact of a perturbation I is
J + Jf + Jf2 + Jf3 + ...
The infinite series of tail-biting feedback terms is in fact
series, and so can be summed up if f is less than 1:
So far, so good. The math here is entirely correct. He goes on to make this point, arguing that if we are uncertain about f, in other words, if there is a distribution of possible f's, then the range of the total system gain 1/(1-f) is likely higher than our intuition might first tell us:
If we knew the value of the feedback f, we could predict the
response to perturbations just by multiplying them by 1/(1-f) "”
call this G for "gain". What happens, Roe and Baker ask, if we do not
know the feedback exactly? Suppose, for example, that our measurements are
corrupted by noise --- or even, with something like the climate,
that f is itself stochastically fluctuating. The distribution of
values for f might be symmetric and reasonably well-peaked around a
typical value, but what about the distribution for G? Well, it's
nothing of the kind. Increasing f just a little increases
G by a lot, so starting with a symmetric, not-too-spread distribution
of f gives us a skewed distribution for G with a heavy right
Again all true, with one small unstated proviso I will come back to. He concludes:
In short: the fact that we will probably never be able to precisely predict
the response of the climate system to large forcings is so far from being a
reason for complacency it's not even funny.
Actually, I can think of two unstated facts that undermine this analysis. The first is that most catastrophic climate forecasts you see utilize gains in the 3x-5x range, or sometimes higher (but seldom lower). This implies they are using an f of between .67 and .80. These are already very high numbers for any natural process. If catastrophist climate scientists are already assuming numbers at the high end of the range, then the point about uncertainties skewing the gain disproportionately higher are moot. In fact, we might tend to actually draw the reverse conclusion, that the saw cuts both ways. His analysis also implies that small overstatements of f when the forecasts are already skewed to the high side will lead to very large overstatements of Gain.
But here is the real elephant in the room: For the vast, vast majority of natural processes, f is less than zero. The author has blithely accepted the currently unproven assumption that the net feedback in the climate system is positive. He never even hints at the possibility that that f might be a negative feedback rather than positive, despite the fact that almost all natural processes are dominated by negative rather than positive feedback. Assuming without evidence that a random natural process one encounters is dominated by negative feedback is roughly equivalent to assuming the random person you just met on the street is a billionaire. It is not totally out of the question, but it is very, very unlikely.
When one plugs an f in the equation above that is negative, say -0.3, then the gain actually becomes less than one, in this case about 0.77. In a negative feedback regime, the system response is actually less than the initial perturbation because forces exist in the system to damp the initial input.
The author is trying to argue that uncertainty about the degree of feedback in the climate system and therefore the sensitivity of the system to CO2 changes does not change the likelihood of the coming "catastrophe." Except that he fails to mention that we are so uncertain about the feedback that we don't even know its sign. Feedback, or f, could be positive or negative as far as we know. Values could range anywhere from -1 to 1. We don't have good evidence as to where the exact number lies, except to observe from the relative stability of past temperatures over a long time frame that the number probably is not in the high positive end of this range. Data from climate response over the last 120 years seems to point to a number close to zero or slightly negative, in which case the author's entire post is irrelevant. In fact, it turns out that the climate scientists who make the news are all clustered around the least likely guesses for f, ie values greater than 0.6.
Incredibly, while refusing to even mention the Occam's Razor solution that f is negative, the author seriously entertains the notion that f might be one or greater. For such values, the gain shoots to infinity and the system goes wildly unstable (nuclear fission, for example, is an f>1 process). In an f>1 world, lightly tapping the accelerator in our car would send us quickly racing up to the speed of light. This is an ABSURD assumption for a system like climate that is long-term stable over tens of millions of years. A positive feedback f>=1 would have sent us to a Venus-like heat or Mars-like frigidity eons ago.
A summary of why recent historical empirical data implies low or negative feedback is here. You can learn more on these topics in my climate video and my climate book. To save you the search, the section of my movie explaining feedbacks, with a nifty live demonstration from my kitchen, is in the first three and a half minutes of the clip below:
There has been a lot of interest in my new climate video. Already we have nearly
450 1500 views at Google video and over 200 700 downloads of the video. I am now releasing the video through YouTube.
YouTube requires that all videos be under 10 minutes, so I have broken the film into six parts. If you want to just preview a portion, the second half of the fourth film and the first half of the fifth are probably the most critical.
A Youtube Playlist for the film is here. This is a cool feature I have not used before, but will effectively let you run the parts end to end, making the 50-minute video more or less seamless.
The individual parts are:
Climate Video Part 1: Introduction; how greenhouse gases work; historical climate reconstructions
Climate Video Part 2: Historical reconstructions; problems with proxies
Climate Video part 3: How much warming is due to man; measurement biases; natural cycles in climate
Climate Video Part 4: Role of the sun; aerosols and cooling; climate sensitivity; checking forecasts against history
Climate Video Part 5: Positive and negative feedback; hurricanes.
Climate Video Part 6: Melting ice and rising oceans; costs of CO2 abatement; conclusions.
You may still stream the entire climate film from Google Video here. (the video will stutter between the 12 and 17 second marks, and then should run fine)
I had a call today from a reporter at the Christian Science Monitor who wanted to discuss climate skepticism. What a disaster of an interview I am! He would ask an open-ended question, and off I would go into feedback theory and then to acoustics and then into helicopter dynamics and back to the ice age and then to temperature measurement in Tucson. I try to follow 6 trains of thought simultaneously and the result is a mess.
The poor reporter was quite friendly and ended with "I am not sure where we are going with this story" which is the universal reporter speak for "your interview was such a mess I am not sure how we would ever use it." LOL. Only by writing, with the implicit governor applied by the keyboard, am I able to organize my thoughts well. Which is why I have never invested in a computer dictation product - I shudder to think what I would find on the page after a session. Which reminds me of the early Doonesbury cartoons with Duke when he was a reporter at the Rolling Stone, when he would come into the his editor's office and claim to have dictated some really powerful stuff, only to find a garbled drug-induced mess, which was obviously a reference to Hunter S. Thompson, who... oh crap, I'm doing it again.
I know I have deluged you with a lot of climate change posts of late. I think this particular post is important, as it is the clearest single argument I can make as to why I am skeptical that man-made global warming will rise to catastrophic levels. It is not comprehensive, it took me 80 pages to do that, but it should get anyone thinking.
It turns out to be quite easy to do a simple but fairly robust reality check of global warming forecasts, even without knowing what a "Watt" or a "forcing" is. Our approach will be entirely empirical, based on the last 100 years of climate history. I am sensitive that we skeptics not fall into the
9/11 Truther syndrome of arguing against a coherent theory from
isolated anomalies. To this end, my approach here is holistic and not
anomaly driven. What we will find is that, extrapolating from history, it is almost impossible to get warming numbers as high as those quoted by global warming alarmists.
The one simple concept you need to understand is "climate sensitivity." As used in most global warming literature, climate sensitivity is the amount of global warming that results from a doubling in atmospheric CO2 concentrations. Usually, when this number is presented, it refers to the warming from a doubling of CO2 concentrations since the beginning of the industrial revolution. The pre-industrial concentration is generally accepted as 280ppm (0.028% of the atmosphere) and the number today is about 380ppm, so a doubling would be to 560ppm.
As a useful, though not required, first step before we begin, I encourage you to read the RealClimate simple "proof" for laymen that the climate sensitivity is 3ºC, meaning the world will warm 3 degrees C with a doubling of CO2 concentrations from their pre-industrial level. Don't worry if you don't understand the whole description, we are going to do it a different, and I think more compelling, way (climate scientists are a bit like the Wizard of Oz -- they are afraid if they make things too simple someone might doubt they are a real wizard). 3ºC is a common number for sensitivity used by global warming hawks, though it is actually at the low end of the range that the UN IPCC arrived at in their fourth report. The IPCC (4th report, page 798) said that the expected value is between 3ºC and 4ºC and that there was a greater chance the sensitivity was larger than 6ºC than that it was 1.5ºC or less. I will show you why I think it is extraordinarily unlikely that the number is greater even than 1.5ºC.
We are going to derive the sensitivity (actually a reasonable range for sensitivity) for ourselves in three steps. First, we will do it a simple way. Then, we will do it a slightly harder but more accurate way. And third, we will see what we would have to assume to get a number anywhere near 3ºC. Our approach will be entirely empirical, using past changes in CO2 and temperature to estimate sensitivity. After all, we have measured CO2 going up by about 100 ppm. That is about 36% of the way towards a doubling from 280 to 560. And, we have measured temperatures -- and though there are a lot of biases in these temperature measurements, these measurements certainly are better than our guesses, say, of temperatures in the last ice age. Did you notice something odd, by the way, in the RealClimate derivation? They never mentioned measured sensitivities in the last 100 years -- they jumped all the way back to the last ice age. I wonder if there is a reason for that?
A First Approximation
OK, let's do the obvious. If we have experienced 36% of a doubling, then we should be able to take the historic temperature rise from CO2 for the same period and multiply it by 2.8 (that's just reciprocal of 36%) and derive the temperature increase we would expect for a full doubling.
The problem is that we don't know the historic temperature rise solely form CO2. But we do know how to bound it. The IPCC and most global warming hawks place the warming since 1900 at about 0.6ºC. Since no one attributes warming before 1900 to man-made CO2 (it did warm, but this is attributed to natural cyclical recovery from the little ice age) then the maximum historic man-made warming is 0.6ºC. In fact, all of that warming is probably not from CO2. Some probably is from continued cyclical warming out of the little ice age. Some, I believe strongly, is due to still uncorrected biases, particularly of urban heat islands, in surface temperature data.
But let's for a moment attribute, unrealistically, all of this 0.6ºC to man-made CO2 (this is in fact what the IPCC does in their report). This should place an upper bound on the sensitivity number. Taking 0.6ºC times 2.8 yields an estimated climate sensitivity of 1.7ºC. Oops. This is about half of the RealClimate number or the IPCC number! And if we take a more realistic number for man-made historic warming as 0.4ºC, then we get a sensitivity of 1.1ºC. Wow, that's a lot lower! We must be missing something important! It turns out that we are, in this simple analysis, missing something important. But taking it into account is going to push our sensitivity number even lower.
A Better Approximation
What we are missing is that the relation between CO2 concentration and warming is not linear, as implied in our first approximation. It is a diminishing return. This means that the first 50 ppm rise in CO2 concentrations causes more warming than the next 50 ppm, etc. This effect has often been compared to painting a window. The first coat of paint blocks out a lot of light, but the window is still translucent. The next coat blocks out more light, but not as much as the first. Eventually, subsequent coats have no effect because all the light is already blocked. CO2 has a similar effect on warming. It only absorbs certain wavelengths of radiation returning to space from earth. Once the absorption of those wavelengths is saturated, extra CO2 will do almost nothing. (update: By the way, this is not some skeptic's fantasy -- everyone in climate accepts this fact).
So what does this mean in English? Well, in our first approximation, we assumed that 36% of a CO2 doubling would yield 36% of the temperature we would get in a doubling. But in reality, since the relationship is a diminishing return, the first 36% of a CO2 doubling will yield MORE than 36% of the temperature increase you get for a doubling. The temperature increase is front-loaded, and diminishes going forward. An illustration is below, with the linear extrapolation in red and the more realistic decreasing exponential extrapolation in blue.
The exact shape and equation of this curve is not really known, but we can establish a reasonable range of potential values. For any reasonable shapes of this curve, 36% of a CO2 doubling (where we are today) equates to from 43% to 63% of the final temperature increase over a doubling. This would imply that a multiplier between 2.3 and 1.6 for temperature extrapolation (vs. 2.8 derived above for the straight linear extrapolation above) or a climate sensitivity of 1.4ºC to 1.0ºC if man-made historic warming was 0.6ºC and a range of 0.9ºC to 0.6ºC for a man-made historic warming of 0.4ºC. I tend to use the middle of this range, with a multiplier of about 1.9 and a man-made historic warming of 0.5ºC to give a expected sensitivity of 0.95ºC, which we can round to 1ºC.
This is why you will often hear skeptics cite numbers closer to 1ºC rather than 3ºC for the climate sensitivity. Any reasonable analysis of actual climate experience over the last 100 years yields a sensitivity much closer to 1ºC than 3ºC. Most studies conducted before the current infatuation with showing cataclysmic warming forecasts came up with this same 1ºC, and peer-reviewed work is still coming up with this same number.
So what does this mean for the future? Well, to predict actual temperature increases from this sensitivity, we would have to first create a CO2 production forecast and, you guessed it, global warming hawks have exaggerated that as well. The IPCC says we will hit the full doubling to 560ppm around 2065 (Al Gore, incredibly, says we will hit it in the next two decades). This means that with about 0.5C behind us, and a 3 sensitivity, we can expect 2.5C more warming in the next 60 years. Multiply that times exaggerated negative effects of warming, and you get instant crisis.
However, since actual CO2 production is already below IPCC forecasts, we might take a more reasonable date of 2080-2100 for a doubling to 560. And, combining this with our derived sensitivity of 1ºC (rather than RealClimate's 3ºC) we will get 0.5C more warming in the next 75-100 years. This is about the magnitude of warming we experienced in the last century, and most of us did not even notice.
I know you are scratching you head and wondering what trick I pulled to get numbers so much less than the scientific "consensus." But there is no trick, all my numbers are empirical and right out of the IPCC reports. In fact, due to measurement biases and other climate effects that drive warming, I actually think the historic warming from CO2 and thus the sensitivity is even lower, but I didn't want to confuse the message.
So what are climate change hawks assuming that I have not included? Well, it turns out they add on two things, neither of which has much empirical evidence behind it. It is in fact the climate hawks, not the skeptics, that need to argue for a couple of anomalies to try to make their case.
Is Climate Dominated by Positive Feedback?
Many climate scientists argue that there are positive feedbacks in the climate system that tend to magnify and amplify the warming from CO2. For example, a positive feedback might be that hotter climate melts sea ice and glaciers, which reduces the reflectiveness of the earth's surface, which causes more sunlight to be absorbed, which warms things further. A negative feedback might be that warmer climate vaporizes more water which forms more clouds which blocks sunlight and cools the earth.
Climate scientists who are strong proponents of catastrophic man-made warming theory assume that the climate is dominated by positive feedbacks. In fact, my reading of the IPCC report says that the climate "consensus" is that net feedback in the climate system is positive and tends to add 2 more degrees of temperature for every one added from CO2. You might be thinking - aha - I see how they got a sensitivity of 3ºC: Your 1ºC plus 2ºC in feedback equals 3ºC.
But there is a problem with that. In fact, there are three problems with this. Here they are:
- We came up with our 1ºC sensitivity empirically. In other words, we observed a 100ppm past CO2 increase leading to 0.5ºC measured temperature increase which implies 1ºC sensitivity. But since this is empirical, rather than developed from some set of forcings and computer models, then it should already be net of all feedbacks. If there are positive feedbacks in the system, then they have been operating and should be part of that 1ºC.
- There is no good scientific evidence that there is a large net positive feedback loop in climate, or even that the feedback is net positive at all. There are various studies, hypotheses, models, etc., but no proof at all. In fact, you can guess this from our empirical data. History implies that there can't be any large positive feedbacks in the system or else we would have observed higher temperatures historically. In fact, we can go back in to the distant historical record (in fact, Al Gore showed the chart I am thinking of in An Inconvenient Truth) and find that temperatures have never run away or exhibited any sort of tipping point effect.
- The notion that a system like climate, which has been reasonably stable for millions of years, is dominated by positive feedback should offend the intuition of any scientist. Nature is dominated in large part by negative feedback processes. Positive feedback processes are highly unstable, and tend to run away to a distant endpoint. Nuclear fission, for example, is a positive feedback process
Do aerosols and dimming imply a higher sensitivity?
Finally, the last argument that climate hawks would employ is that anthropogenic effects, specifically emission of SO2 aerosols and carbon black, have been reflecting sunlight and offsetting the global warming effect. But, they caution, once we eliminate these pollutants, which we have done in the West (only to be offset in China and Asia) temperatures will no longer be suppressed and we will see the full extent of warming.
First, again, no one really has any clue the magnitude of this effect, or even if it is an effect at all. Second, its reach will tend to be localized over industrial areas (since their presence in the atmosphere is relatively short-lived), whereas CO2 acts worldwide. If these aerosols and carbon black are concentrated say over 20% of the land surface of the world, this means they are only affecting the temperature over 5% of the total earth' s surface. So its hard to argue they are that significant.
However, let's say for a moment this effect does exist. How large would it have to be to argue that a 3.0ºC climate sensitivity is justified by historical data? Well, taking 3.0ºC and dividing by our derived extrapolation multiplier of 1.9, we get required historic warming due to man's efforts of 1.6ºC. This means that even if all past 0.6ºC of warming is due to man (a stretch), then aerosols must be suppressing a full 1ºC of warming. I can't say this is impossible, but it is highly unlikely and certainly absolutely no empirical evidence exists to support any number like this. Particularly since dimming effects probably are localized, you would need as much as 20ºC suppression in these local areas to get a 1ºC global effect. Not very likely.
Why the number might even be less
Remember that when we calculated sensitivity, we needed the historical warming due to man's CO2. A simple equation for arriving at this number is:
Warming due to Man's CO2 = Total Historic Measured Warming - Measurement Biases - Warming from other Sources + Warming suppressed by Aerosols
This is why most skeptics care if surface temperature measurements are biased upwards or if the sun is increasing in intensity. Global warming advocates scoff and say that these effects don't undermine greenhouse gas theory. And they don't. I accept greenhouse gases cause some warming. BUT, the more surface temperature measurements are biased upwards and the more warming is being driven by non-anthropogenic sources, the less that is being caused by man. And, as you have seen in this post, the less warming caused by man historically means less that we will see in the future. And while global warming hawks want to paint skeptics as "deniers", we skeptics want to argue the much more interesting question "Yes, but how much is the world warming, and does this amount of warming really justify the costs of abatement, which are enormous."
As always, you can find my Layman's Guide to Skepticism about Man-made Global Warming here. It is available for free in HTML or pdf download, or you can order the printed book that I sell at cost. My other recent posts about climate are here.
We all know why Newsweek and many others (like Kevin Drum) choose to use the term "denier" for those of us who are skeptical of catastrophic anthropogenic global warming: These media folks, who are hesitant to use the word "terrorist" because of its emotional content, want to imply that we skeptics are somehow similar to Holocaust deniers.
But beyond just the issues of false emotional content, the word denier is incorrect as applied to most skeptics, including myself, and helps man-made warming hawks avoid a difficult argument. I try to be careful to say that I am a skeptic of "catastrophic man-made (or anthropogenic) global warming theory."
- So, does that mean I think the world is not warming? In fact, the evidence is pretty clear that it is warming (though perhaps not by as much as shown in current surface temperature databases).
- So does this mean that I think that human activities are not causing some warming? In fact, I do think man-made CO2 is causing some, but not all the current 20th century warming trend. I also think that man's land use (urbanization, irrigated agriculture, etc) has effects on climate.
Where I really get skeptical is the next proposition -- that man's burning of fossil fuels is going to cause warming in the next century that will carry catastrophic impacts, and that these negative effects will justify massive current spending and government interventions (that will have their own negative consequences in terms of lost economic growth, increased poverty, and reduction in freedoms).
Strong supporters of catastrophic man-made global warming theory do not usually want to argue this last point. It is much easier to argue points 1 and 2, because the science is pretty good that the earth has warmed (though the magnitude is in question) and that CO2 greenhouse effect does cause warming (though the magnitude is in question). That is why skeptics are called deniers. It is in effect a straw man that allows greenhouse supporters to stay on 1 and 2 without getting into the real meat of the question.
Here is a quick example to prove my point. Follow me for three paragraphs, then ask yourself if you have ever heard any of this in the media or on any RealClimate-type site's FAQ.
Anthropogenic global warming hawks admit that the warming solely from the CO2 greenhouse effect will likely NOT rise to catastrophic levels. So how do they get such big, scary forecasts? The answer is positive feedback.
Almost every process you can think of in nature operates by negative
feedback, meaning that an input to a system is damped. Roll a ball, and eventually friction and wind resistance
it to a stop. Positive feedback means that an input to the system is multiplied and increased. Negative feedback is a ball in the bottom of a bowl, always returning to the center; positive feedback is a ball perched precariously at the top of a
mountain that will run faster and faster downhill with a tiny push. Positive feedback
breeds instability, and processes that operate by positive feedback are
dangerous, and usually end up in extreme states -- these processes tend
"run away" like the ball rolling down the hill. Nuclear fission, for
example, is a positive feedback process.
Current catastrophic man-made global warming theory asserts that our climate is dominated
by positive feedback. The last UN IPCC report posits that a small increase in
temperature from CO2 is multiplied 2,3,4 times or more by positive
feedbacks like humidity and ice albedo. So a modest degree or degree and a half of warming from the greenhouse effect becomes a scary five or eight degrees of warming in the next century once any number of hypothesized positive feedbacks are applied. Add to this exaggerated, sometimes over-the-top visions of possible negative consequences, and that is how global warming hawks justify massive government action.
OK, that is a very brief description of what I consider a sophisticated reason to be skeptical: Most catastrophic warming forecasts depend on positive feedback loops, feedbacks for which we have little or no evidence and which don't tend to dominate in other stable systems. So how many times have you seen this issue discussed? Zero? Yeah, its so much easier just to call us deniers.
If you are interested, here is slightly longer version of my skeptic's point of view. Here is my much longer version. Here is the specific chapter that discusses feedback loops. Here is Roy Spencer discussing problems with studies trying to measure these feedbacks.
Postscript: By the way, it is in this context that the discussions about restating temperatures and problems with historical surface temperature measurements are important. Exaggerated historical warming numbers leave more room to posit positive feedback loops. Lower historical numbers, or evidence past warming is driven by non-man-made sources (e.g. solar activity), leave less room to justify positive feedback loops.
Update: RealClimate has posted their six steps to explain catastrophic warming from CO2. Seems have buried the feedback issue. Note that forcings mentioned here include feedbacks, they are not from CO2 alone but from CO2 + positive feedback. Strange they didn't mention this.
I was trying to think about what I wanted to do for my last post in my recent orgy of global warming writing. My original attempt to outline the state of the climate skeptic's case ballooned into 80+ pages, so there may be many people who rationally just have no desire to tackle that much material. So I decided for this last post to try to select the one argument I would use if I had only 60 seconds to make the climate skeptic's case. But how do you boil down 80 pages to a few simple statements?
I'm not that interested in the Sun or cosmic rays -- they are interesting topics, but its dumb to try to argue we overestimate our understanding of man's impact on climate only to counter with topics we understand even less. One of the reasons I wrote the paper in the first place was because I thought recent skeptical documentaries spent too much time on this subject. And I would not get into tree rings or ice cores or other historic proxy data, though there is a lot happening in these areas. I wouldn't even delve into the hysterical treatment of skeptics by man-made climate advocates -- these are ad hominem issues that are useful to understand in a more comprehensive view but don't make for strong stand-alone arguments.
Anyway, here goes, in a logic chain of 8 steps.
- CO2 does indeed absorb reflected sunlight returning to space from earth, having a warming effect. However, this effect is a diminishing return -- each successive increment of CO2 concentrations will have a much smaller effect on temperatures than the previous increment. Eventually, CO2 becomes nearly saturated in its ability to absorb radiation. The effect is much like painting a red room with white paint. The first coat covers a lot of red but some still shows through. Each additional coat will make the room progressively whiter, but each successive coat will have a less noticeable effects than the previous coat, until the room is just white and can't get any whiter.
- In the 20th century, the UN IPCC claims Earth's surface temperatures have increased by about a 0.6 degree Celsius (though there are some good reasons to think that biases in the installation of temperature instruments have exaggerated this apparent increase). To be simple (and generous), let's assume all this 0.6C increase is due to man-made greenhouse gasses. Some may in fact have been due to natural effects, but some may also have been masked by man-made sulfate aerosols, so lets just call man-made warming to be 0.6C.
- Since the beginning of the industrial revolution, it is thought that man has increased atmospheric CO2 concentrations from 0.028% of the atmosphere to 0.038% of the atmosphere. Since scientists often talk about the effect of a doubling of CO2, this historic rise in CO2 is 36% of a doubling.
- Using simple math, we see that if temperatures have risen 0.6C due to 36% of a doubling, we might expect them to rise by 1.67C for a full doubling to 0.056% of the atmosphere. But this assumes that the rise is linear -- and we already said (and no one denies) that it is in fact a diminishing return relationship. Using a truer form of the curve, a 0.6C historic rise for 36% of a doubling implies a full doubling would raise temperatures by about 1.2C, or about 0.6C more than we have seen to date (see chart below). This means that the magnitude of global warming in the next century might be about what we have seen (and apparently survived) since 1900.
- Obviously, there is some kind of disconnect here. The IPCC predicts temperature increases in the next century of 4-8 degrees C. Big difference. In fact, the IPCC predicts we will get a 0.5C rise in just 20 years, not 70-100. Whereas we derived a climate sensitivity of 1.2 from empirical data, they arrive at numbers between 3 and 4 or even higher for sensitivity. The chart below shows that to believe sensitivity is 3, we would have to have seen temperature rises due to man historically of 1.5C, which nobody believes.
So how do they get accelerating temperatures from what they admit to be a diminishing return relation between CO2 concentration and temperature? And for which there is no empirical evidence? Answer: Positive feedback.
- Almost every process you can think of in nature operates by negative
feedback. Roll a ball, and eventually friction and wind resistance bring
it to a stop. Negative feedback is a ball in the bottom of a bowl; positive feedback is a ball perched precariously at the time of a mountain. Positive feedback
breeds instability, and processes that operate by positive feedback are
dangerous, and usually end up in extreme states -- these processes tend to
"run away" like the ball rolling down the hill. Nuclear fission, for example, is a positive feedback process. We should be happy there are not more positive feedback
processes on our planet. Current man-made global warming theory, however, asserts that our climate is dominated by positive feedback. The IPCC posits that a small increase in temperature from CO2 is multiplied 2,3,4 times or more by positive feedbacks like humidity and ice albedo.
- There are three problems with these assumptions about positive feedback. One, there is no empirical evidence at all that positive feedbacks in climate dominate negative feedbacks. The 20th century temperature numbers we discussed above show no evidence of these feedbacks. Two, the long-term temperature record demonstrates that positive feedbacks can't dominate, because past increases in temperature and CO2 have not run away. And three, characterizations of stable natural processes as being dominated by positive feedback should offend the intuition and common sense of any scientist.
- An expected 21st century increase of 0.5 or even 1 degree C does not justify the massive imposed government interventions that will be costly both in dollars and lost freedoms. In particular, the developing world will be far better off hotter by a degree and richer than it would be cooler and poorer. This is particularly true since sources like an Inconvenient Truth wildly exaggerate the negative effects of global warming. There is no evidence tornadoes or hurricanes or disease or extinction are increasing as the world warms, and man-made warming advocates generally ignore any potential positive effects of warming. As to rising sea levels, the IPCC predicts only a foot and a half of sea level rise even with 4 or more degrees of warming. Sea level rise from a half to one degree of warming would be measured at most in inches.
OK, so that was more than 60 seconds. But it is a lot less than 80 pages. There is a lot of complexity behind every one of these statements. If you are intrigued, or at least before you accuse me of missing something critical, see my longer paper on global warming skepticism first, where all these issues and much more (yes, including tree rings and cosmic rays) are discussed in more depth.
I turned off comments on the published HTML version of my Skeptical Layman's Guide to Man-made Global Warming (pdf here) to avoid spam problems. However, it was not my intention to forgo the ability of readers to comment. So I am going to link this comment thread from the bottom of each chapter.
I have gotten several comments back similar to what Steven Dutch says here:
So You Still Don't Believe In Global Warming?
Fine. Here's what you have to do....
Show conclusively that an increase in carbon dioxide will
not result in global warming. Pointing to flaws in the climate models,
possible alternative explanations, and unanswered questions won't cut it. We
know carbon dioxide traps infrared and we know climate is
getting warmer. There's a plausible cause and effect relationship there. You
have to show there is not a causal link. You can do that either by
identifying what is the cause ("might be" or "possible alternative"
isn't good enough) or by showing that somehow extra carbon dioxide does
not trap solar heat.
This might be correct if we were in a college debating society, where the question at hand was "does man contribute to global warming?" However, we are in a real world policy debate, where the question is instead "Is man causing enough warming and thereby contributing to sufficiently dire consequences to justify massive interventions into the world economy, carrying enormous costs and demonstrable erosions in individual freedoms." Remember, we know monetary and liberty costs of abatement with a fair amount of cerntainty, so in fact the burden of proof is on man-made global warming advocates, not skeptics, who need to prove the dangers from the man-made component of global warming outweigh the costs of these abatements.
That is why the premise for my paper is as follows:
There is no doubt that CO2 is a
greenhouse gas, and it is pretty clear that CO2 produced by man has an
incremental impact on warming the Earth's surface.
warming is the result of many natural and man-made factors, and it is
extraordinarily difficult to assign all the blame for current warming to
In turn, there are very good reasons to suspect that climate
modelers may be greatly exaggerating future warming due to man. Poor
economic forecasting, faulty assumptions about past and current conditions, and
a belief that climate is driven by runaway positive feedback effects all
contribute to this exaggeration.
As a result, warming due to man's
impacts over the next 100 years may well be closer to one degree C than the
forecasted six to eight. In either case, since AGW supporters tend to grossly
underestimate the cost of CO2 abatement, particularly in lost wealth creation
in poorer nations, there are good arguments that a warmer but richer world,
where aggressive CO2 abatement is not pursued, may be the better end state than
a poor but cooler world.
Interventionists understand that their job is not to prove that man is causing some global warming, but to prove that man is doing enough damage to justify massive economic interventions. That is why Al Gore says tornadoes are increasing when they are not, or why he says sea levels will rise 20 feet when even the IPCC says a foot and a half. And I will leave you with this quote
from National Center for Atmospheric Research (NOAA) climate researcher and
global warming action promoter, Steven Schneider:
We have to
offer up scary scenarios, make simplified, dramatic statements, and make little
mention of any doubts we have. Each of us has to decide what the right balance
is between being effective and being honest.
Comment away. I don't edit or delete comments, except in the cases of obvious spam.
Update: Here is another reason why there is an important difference between "man causes any warming at all" and "man causes most of the warming."
I will not even try do full justice here to the basic theory
of AGW theory. I highly encourage you to check out RealClimate.org. This is probably
the premier site of strong AGW believers and I really would hate to see AGW
skeptics become like 9/11 conspiracists, spending their time only on
like-minded sites in some weird echo chamber.
If you are reading this, you probably know that CO2 is what
is called a greenhouse gas. This means that it can temporarily absorb
radiation from the Earth, slowing its return to space and thereby heating the
troposphere (the lower 10KM of the atmosphere) which in turn can heat up the
Earth's surface. You probably also know that CO2 is not the only
greenhouse gas, and that water vapor, for example, is actually a much stronger
and more prevalent greenhouse gas.
It is important to understand that the greenhouse gas effect
is well-understood in the laboratory. No one really disagrees that, all
other effects held constant in a laboratory, CO2 will absorb certain
wavelengths of reflected sunlight. What may or may not be
well-understood, depending on your point of view, is how this translates to the
actual conditions in our chaotic climate. Does this effect dominate all
other climate effects, or is it trivial compared to other forces at work?
Does this greenhouse effect lead to runaway, accelerating change, or are there
opposing forces that tend to bring the climate back in balance? These are
hugely complex questions, and scientists are a long way from answering them
But wait, that can't be right -- scientists seem so
sure! Well, some scientists, particularly those close to microphones,
seem sure. Their proof usually follows one or both of these paths:
- Some scientists argue that they believe they have
accounted for all the potential natural causes, or "forcings," in the
climate that might cause the warming we have observed over the last century,
and they believe these natural forcings are not enough to explain recent
temperature increases, so therefore the changes must be due to man.
This seems logical, until I restate their logic this way: "the
warming must be due to man because we can't think of anything else it
- Scientists have created complicated models to predict
future climate behavior. They argue that their models show man-made
CO2 causing most 20th century warming. Again this sounds good,
until one understands that when these models were first run, they were
terrible at explaining history. Since these first runs, scientists
have tweaked the models until they match historical data better. So,
in effect, they are saying that manmade CO2 is the cause of historical
warming because the models they tweaked to match history"¦ are very good at
matching history; and because the models they programmed with CO2 as the
major driver of climate show that"¦CO2 is the major driver of
climate. We will see a lot of such circular analysis in later
The best evidence we could expect to find (lacking a second
identical Earth we can use as a control in an experiment) is to find a historic
correlation between temperature and CO2 that is stronger than the correlation
between temperature and anything else (and of course, even this would not imply
causation). There is a lot of argument whether we have that or not, a
topic I will cover in the next chapter. Of course, the lack of unequivocal
evidence at this point does not make the AGW theory wrong, just still"¦
Before we get to the historical evidence, though, there may
be a few other facts about CO2 and warming that you don't know:
- CO2 is a really, really small part of the atmosphere.
Currently CO2 makes up about 0.0378% of the atmosphere, up from an
estimated 0.0280% before the industrial revolution. (Just to give an
idea of scale, if you were flying from Los Angeles to New York City,
traveling 0.0378% of the distance would not even get you off the runway at
LAX. AGW advocates are arguing that a CO2 concentration increase of
0.009% has heated the world over a half a degree C.
- The maximum warming should, by greenhouse gas theories,
occur in the troposphere (the first 10km or so of atmosphere).
Global warming theory strongly predicts that the warming in the
troposphere should be higher than warming at the ground. We will see
later that the opposite is actually occurring.
- The radiated energy returning to space consists of a wide
spectrum of wavelengths. Only a few of these wavelengths are
absorbed by CO2. Once these few wavelengths are fully absorbed,
additional CO2 in the atmosphere has no effect whatsoever. Also,
these absorbed frequencies overlap with the absorption of other gasses,
like water, which further lessens the incremental effect of extra CO2.
What does this mean? In
effect, the warming effect of CO2 is a diminishing return relationship.
The first increase of, say, 100 parts per million (ppm) in the atmosphere has a
greater effect than the next 100 ppm, and so on until increased CO2 has
essentially no effect at all.
I once bought a house that had
fuchsia walls in the kitchen and family room (really). I spent all night
painting the rooms with a coat of white paint, and when I was done, I found
that some of the fuchsia still showed through the white paint, making it
kind of light pink. A second coat of white made the wall nearly perfectly
white. The effects of CO2 in the atmosphere are similar, with the first
"coat" making for the most warming and later "coats" having much less effect
but still adding a bit. At some point, the wall is white and more coats
have no effect.
This relationship of CO2 to warming
is usually called sensitivity, and is often expressed as the number of degrees
of global warming that would result from a doubling in global temperature.
There are lots of values floating
around out there for sensitivity, but a preponderance (I won't say consensus)
seem to center on an increase of one degree C for a doubling of CO2 levels from
the pre-industrial figure of about 280ppm. Note that you will see numbers
much higher than this, but these generally include feedback loops, which we
will get to later. Without feedbacks, 0.5 to maybe 1.5 degrees seems like
a fairly well accepted number for sensitivity, though there are people on both
side of this range.
Motl provides a handy approximation of the diminishing return effect from
CO2 concentration on temperature. I have taken his approximation and
graphed it below.
This is a very crude approximation,
but the shape of the curve is generally correct (if you exclude feedbacks,
which we will discuss in MUCH more depth later). Other more
sophisticated approximations generally show the initial curve less steep, and
the asymptote less pronounced. Never-the-less, it is generally accepted
by most all climate scientists that, in the absence of feedbacks, future
increases in atmospheric CO2 will have less effect on world temperature than
past increases, and that there is a cap (in this chart around 1.5 degrees C) on
the total potential warming.
Note that this is much smaller than
you will see in print. The key is in "feedbacks" or secondary effects
that accelerate or slow warming. We will discuss these in more depth
later, but typically AGW supporters believe these will triple the sensitivity
numbers, so a non-feedback sensitivity of one degree would be tripled to three
degrees. Remember, though, these three points:
· Warming from CO2 is a diminishing return, such that future CO2 increases
has less effect than past CO2 increases
· In the absence of feedback, a doubling of CO2 might increase
temperatures one degree C
· In the absence of feedback, the total temperature increase from future
CO2 increases is capped, maybe as low as 1-1.5 degrees C.
We have gotten well into this paper, and we still have not
discussed what is perhaps the most problematic aspect of AGW research:
the computer models.
If an economist came up with a computer model that he claimed could predict
the market value of every house in the world in the year 2106 within $1,000,
would you believe him? No, you would say he was nuts -- there is way too
much uncertainty and complexity. Climate, of course, is not the same as
housing prices. It is in fact, much, much more complex and more difficult
to predict. There is nothing wrong with trying to predict the complex and
chaotic. But there is a certain sense of hubris in believing that one has
succeeded with the kind of 95% certainty figures used by the IPCC.
All climate forecasting models are created by a pretty insular and
incestuous climate science community that seems to compete to see who can come
up with the most dire forecast. Certainly there are financial incentives
to be as aggressive as possible in forecasting climate change, since funding
dollars tend to get channeled to those who are the most dramatic.
The global warming community spends a lot of time with ad hominem attacks
on skeptics, usually accusing them of being in the pay of oil and power
companies, but they all know that their own funding in turn would dry up
rapidly if they were to show any bit of skepticism in their own work.
The details of these models is beyond the scope of this paper.
However, it is important to understand how they work in broad outlines.
The modelers begin with certain assumptions about climate that they build
into the model. For example, the computers themselves don't somehow
decide if CO2 is a more important forcing on the climate than solar activity "“
the modelers, by the assumptions the feed into the model, decide these
things. The models return the result that CO2 is the most important
driver of climate in the coming century because their programmers built them
with that assumption, not because the model somehow sorts through different
inputs and comes up with the key drivers on its own.
Because the models have been built to test man's possible impact on the
climate via greenhouse gas emissions, they begin with an econometric forecast
of world economic growth, and, based upon assumptions about fuel sources and
efficiencies, they convert this economic growth into emissions forecasts.
The models generally contain subroutines that calculate, again based upon a
variety of assumptions, how man-made CO2 plus other inputs will change the
atmospheric CO2 concentration. Then, via assumptions about climate
sensitivity to CO2 and various feedback loops programmed in, the models will
create forecasts of temperatures, precipitation, etc. These models,
depending on their complexity, will show regional variations in many of these
variables. Finally, the models are tuned so that they better match
history, in theory making them more accurate for the future.
One should note that while the IPCC asked modelers to look at a series of
different cases, the only substantial difference between these cases is the
volume of CO2 and other greenhouse gasses produced. In other words, the
only sensitivity the IPCC seriously modeled was on levels of CO2. No
other contingency "“ e.g. potential variations in global temperature sensitivity
to CO2, solar output, land use "“ were considered. This should give you an
idea of how hard-wired the anthropogenic causation is in the IPCC process.
In this section, I will begin by discussing the models' basic assumptions
about the climate. I will then discuss the econometric forecasts they are
founded on, the assumptions about CO2 sensitivity and feedback processes, and
finally model tuning and their ability to match history.
At any one time, thousands of people are being paid literally millions of
dollars on Wall Street to try to model the behavior of various stock indices
and commodity prices. The total brain power and money power thrown over
the last 50 years at trying to build an accurate predictive model for financial
markets literally dwarfs, by a factor of 100 or more, the cumulative resources
spent to date on long-term climate modeling. Financial markets are
incredibly complex, and they are driven by hundreds of variables.
Interest rates, corporate profits, loan default rates, mortgage refinance
rates, real estate prices, GDP growth, exchange rates, etc. all tend to drive
the behavior of financial markets. And no one has cracked the code.
Sure, some people have built successful short-term trading models, but people
have mostly lost their shirts when they have tried to make long-term bets based
on computer financial models that beautifully matched history but failed to
accurately predict the future.
How is it possible that a model that accurately represents the past fails to
accurately predict the future? Financial modelers, like climate modelers,
look to history in building their models. Again, like climate modelers,
they rely both on theory (e.g. higher interest rates should generally mean
lower stock prices) as well as observed correlations in the historic data
set. The problem they meet, the problem that every modeler meets but most
especially the climate modeler, is that while it is easy to use various
analysis tools to find correlations in the data, there is often nothing that
will tell you if there is really a causal relationship, and which way the
causality runs. For example, one might observe that interest rates and exchange
rates move together. Are interest rate changes leading to exchange rate
adjustments, or vice versa? Or, in fact, are they both caused by a third
variable? Or is their observed correlation merely coincidence?
It was once observed that if an old AFL football team wins the Superbowl, a
bear market will ensue on Wall Street in the next year, while an NFL team
victory presaged a bull market. As of 1997, this correlation held for 28
of the last 31 years, a far better prediction record than that of any Wall
Street analyst. But of course this correlation was spurious, and in the
next 4 years it was wrong every time. Had someone built a financial model
on this indicator, it would have looked great when he ran it against history,
but he would have lost his shirt using it.
Want a better prediction record? For seventeen straight US
presidential election cycles, from 1936 to 2000, the winner of the election was
accurately predicted by"¦the Washington Redskins. In particular, if the
Redskins won their last home game before the election, the party that occupies
the White House holds it in the election. Otherwise, if the Redskins
lose, the opposition party wins. Seventeen in a row! R-squared of
one! Success against odds of 131,072:1 of guessing all 17 right.
But of course, the input was spurious, and in 2004, soon after this
relationship made the rounds of the Internet, the algorithm failed.
This is why we spent so much time in the previous chapter on evaluating
historic correlations between CO2 and temperature. Because the models are
built on an assumption that not only is temperature strongly correlated with
CO2, but that temperature is historically highly stable without this outside
anthropogenic forcing. If there are problems with this assumed causation,
which we saw there are, then there in turn are major inherent problems with the
models themselves. As climate scientist Syun-Ichi Akasofu of the
International Arctic Research Center at University of Alaska Fairbanks wrote:
The computers are "taught" that the temperature
rise during the last hundred years is due mostly to the greenhouse effect. If
the truth is that only about 10% of the present warming is caused by the
greenhouse effect, the computer code must be rewritten
Remember what I said earlier: The models produce the result that there
will be a lot of anthropogenic global warming in the future because they are
programmed to reach this result. In the media, the models are used as a
sort of scientific money laundering scheme. In money laundering, cash
from illegal origins (such as smuggling narcotics) is fed into a business that
then repays the money back to the criminal as a salary or consulting fee or
some other type of seemingly legitimate transaction. The money he gets
back is exactly the same money, but instead of just appearing out of nowhere, it
now has a paper-trail and appears more legitimate. The money has been
In the same way, assumptions of dubious quality or certainty that presuppose
AGW beyond the bounds of anything we have see historically are plugged into the
models, and, shazam, the models say that there will be a lot of anthropogenic
global warming. These dubious assumptions, which are pulled out of thin
air, are laundered by being passed through these complex black boxes we call
climate models and suddenly the results are somehow scientific proof of
AGW. The quality hasn't changed, but the paper trail looks better, at
least in the press. The assumptions begin as guesses of dubious quality
and come out laundered at "settled science." Climate
Scientists Garth Paltridge wrote:
It needs to be understood that any reasonable
simulation even of present climate requires computer models to be tuned. They contain
parameters (that is, pieces of input information) whose numerical values are
selected primarily to give the right answer about today's climate rather than
because of some actual measurement. This was particularly so in the
mid-eighties. The problem with tuning is that it makes any prediction of
conditions different from those of the present far less believable. Even today
the disease of "tuneable parameters" is still rampant in climate
models, although fairly well hidden and not much spoken of in polite society.
The scientifically-inclined reader might try sometime asking a climate
researcher just how many such parameters there are in his or her latest model.
The reader will find there are apparently lots of reasons why such a question
is ridiculous, or if not ridiculous then irrelevant, and if not irrelevant then
unimportant. Certainly the enquirer will come away having been made to feel
The IPCC has never been able to choose a particular climate model it thinks
is best. Instead, it aggregates ten or twelve of them and averages their
results, hoping that if there are errors in the climate models, they will
average out somehow (forgetting that systematic errors don't average out, as we
discussed earlier in the context of historic temperature
reconstructions). The one thing the IPCC does do to bring some order to
all this is to establish baseline econometric and emissions scenarios for all
the teams to feed into the front end of their models. That way, for a given
forecast case, they know variation in model output is due to differing
climate-related assumptions rather than differing economic assumptions.
But a funny thing happens when one tries to make an economic growth forecast
for 100-year periods, as the IPCC has: Very small changes in assumptions make
enormous differences. Here is a simple example. An economy that
grows by 3% per year will be 19x larger in 100 years. However, if that
economy were to grow instead by 4% rather than 3%, it will be 51x larger in 100
years. So a change in the growth rate by one percentage point yields a
final size nearly 2.7 times larger. The same is true with
forecasting CO2 growth "“ a very small change in assumptions can lead to very
large differences in absolute production.
After release of the 3rd IPCC report in 2001, researchers Ian
Castles, formerly the head of Australia's national office of statistics, and
David Henderson of the Westminster Business School and formerly the chief
economist of the OECD, decided to scrutinize
the IPCC's economic assumptions. They found that the IPCC had made a
fundamental mistake in crafting their econometrics, one that caused all of
their economic growth estimates (and therefore estimates of CO2 production) to
be grossly overestimated. Based on the IPCC assumptions, South Africa
ends up with a GDP per capita far in excess of the United States by the year
2100. Incredibly, the IPCC numbers imply that Algeria, Argentina, Libya,
Turkey, and North Korea will all pass the US in per capita income by the end of
Beyond making it clear that there is an element of the absurd in the IPCC's
economic forecasting approach, these errors tend to inflate CO2 forecasts in
two ways. First, CO2 forecasts are raised because, in the models, larger
economies produce more CO2. Second, though, the models assume different
rates for CO2 production per unit of GDP for each country. Most of the
countries the IPCC shows growing so fast "“ Algeria, South Africa, Libya, North
Korea, etc. "“ have lower than average CO2 efficiencies (i.e. higher than
average CO2 production per unit of GDP), so excess growth assumptions in these
countries has a disproportionate impact on projected CO2 emissions. By
the way, it would be interesting to see if the IPCC is using marginal rather
than average rates. For example, France has a very low average rate of
CO2 per unit of GDP because of its nukes, but its marginal growth is met mostly
with fossil fuels.
I can't say whether these same mistakes exist in the 2007 4th
Assessment. However, since the IPCC flatly rejected Castles and
Henderson's critique, it is likely the same methodology was used in 2007 as in
2001. For example, here are the CO2 emissions forecasts from the 4th
assessment "“ notice most all of them have a step-change increase in slope
between history and the future. Just look at the jump across the dotted
line in lead case A1B, and several are even steeper.
So what does this mean? Remember, small changes in growth rate make
big differences in end values. For example, below are the IPCC fourth
assessment results for CO2 concentration. If CO2 concentrations were to
increase at about the same rate as they are today, we would expect an end value
in 2100 of between 520 and 570 ppm, as opposed to the IPCC numbers below where
the projection mean is over 800 in 2100. The difference is in large part
in the economic growth forecasts.
Since it is not at all clear that the IPCC has improved its forecasting
methodology over the past years, it is instructive as one final exercise to go
back to the 1995 emissions scenarios in the 2nd assessment.
Though the scale is hard to read, one thing is clear "“ only 10 years later we
are well below most of the forecasts, including the lead forecast is92a (this
over-forecasting has nothing to do with Kyoto, the treaty's impact has been
negligible, as will be discussed later). One can be assured that if the
forecasts are already overstated after 10 years, they will be grossly
overstated in 100.
As discussed earlier, climate sensitivity generally refers to the expected
reaction of global temperatures to a arbitrary change in atmospheric CO2
concentration. In normal usage, it is usually stated as degrees Celsius
of global warming from a doubling in CO2 concentrations from pre-industrial
levels (approx 280 ppm to 560 ppm). The IPCC and most AGW supporters put
this number at about 3.5 to 4.0 degrees C.
But wait "“ earlier I said the number was probably more like 1.0C, and that
it was a diminishing return. Why the difference? Well, it has to do
with something called feedback effects.
Before I get into these, let's think about a climate sensitivity of 4
degrees C, just from a historical standpoint. According to the IPCC, CO2
has increased by about 100ppm since 1880, which is about 36% of the way to a
doubling. Over this same time period, global temperatures have increased
about 0.7C. Since not even the most aggressive AGW supporter will attribute all
of this rise to CO2 levels, let's be generous and credit CO2 with 0.5C.
So if we are 36% of the way to a doubling, and giving CO2 credit for 0.5
degrees, this implies that the sensitivity is probably not more than 1.4
degrees C. And we only get a number this high if we assume a linear
relationship "“ remember that CO2 and temperature are a diminishing return
relation (chart at right), so future CO2 has less impact on temperature than
past CO2, so 1.4 would be at the high end. In fact, using the logarithmic
relationship we saw before, 0.5 degrees over 36% of the doubling would imply a
sensitivity around 1.0. So, based on history, we might expect at worst
another 0.5C from warming over the next century.
Most AGW supporters would argue that the observed sensitivity over the last
30 years has been suppressed by dimming/sulfate aerosols. However, to get
a sensitivity of 4.0, one would have to assume that without dimming, actual
warming would have been about 2.0C. This means that for the number 4.0 to
1. Absolutely nothing else other than CO2 has been causing warming in the
last 50 years AND
2. Sulfate aerosols had to have suppressed 75% of the warming, or about
1.5C, numbers far larger than I have seen anyone suggest. Remember that
the IPCC classifies our understanding of this cooling effect, if any, as "low"
But in fact, even the IPCC itself admits that its models assume higher
sensitivity than the historically observed sensitivity. According to the
fourth IPCC report, a number of studies have tried to get at the sensitivity
historically (going back to periods where SO2 does not cloud the picture).
Basically, their methodology is not much different in concept than
the back of the envelope calculations I made above.
These are shown in a) below, which shows a probability distribution of what
sensitivity is (IPCC4 p. 798). Note many of the highest probability values of
these studies are between 1 and 2. Also note that since CO2 content is,
as the IPCC has argued, higher than it has been in recorded history, any
sensitivities calculated on historical data should be high vs. the sensitivity
going forward. Now, note that graph c) shows how a number of the climate
models calculate sensitivity. You can see that their most likely values
are consistently higher than any of the historical studies from actual
data. This means that the climate models are essentially throwing out
historical experience and assuming that sensitivity is 1.5 to 2 times higher
going forward, despite the fact a diminishing return relationship says it
should be lower.
Sensitivity, based on History
Sensitivity that is built into the models (Sorry, I still have no idea
what "constrained by climatology" means, but the text of the report makes it clear
that these sensitivities popped out of climate models
So how do these models get to such high sensitivities? The answer, as
I have mentioned, is positive feedback.
Let me take a minute to discuss positive feedbacks. This is something
I know a fair amount about, since my specialization at school in mechanical
engineering was in control theory and feedback processes. Negative
feedback means that when you disturb an object or system in some way, forces
tend to counteract this disturbance. Positive feedback means that the
forces at work tend to reinforce or magnify a disturbance.
You can think of negative feedback as a ball sitting in the bottom of a
bowl. Flick the ball in any direction, and the sides of the bowl,
gravity, and friction will tend to bring the ball back to rest in the center of
the bowl. Positive feedback is a ball balanced on the pointy tip of a
mountain. Flick the ball, and it will start rolling faster and faster
down the mountain, and end up a long way away from where it started with only a
small initial flick.
Almost every process you can think of in nature operates by negative
feedback. Roll a ball, and eventually friction and wind resistance bring
it to a stop. There is a good reason for this. Positive feedback
breeds instability, and processes that operate by positive feedback are
dangerous, and usually end up in extreme states. These processes tend to
"run away." I can illustrate this with an example:
Nuclear fission is a positive feedback process. A high energy neutron
causes the fission reaction, which produces multiple high energy neutrons that
can cause more fission. It is a runaway process, and it is dangerous and
unstable. We should be happy there are not more positive feedback
processes on our planet.
Since negative feedback processes are much more common, and since positive
feedback processes almost never yield a stable system, scientists assume that
processes they meet are negative feedback until proven otherwise. Except
in climate, it seems, where everyone assumes positive feedback is common.
In global warming models, water vapor plays a key role as both a positive
and a negative feedback loop to climate change. Water vapor is a far more
powerful greenhouse gas than CO2, so its potential strength as a feedback
mechanism is high. Water comes into play because CO2 driven warming will
put more water vapor in the atmosphere, because greater heat will vaporize more
water. If this extra vapor shows up as more humid clear air, then this in
turn will cause more warming as the extra water vapor absorbs more energy and
accelerates warming. However, if this extra water vapor shows up as
clouds, the cloud cover will tend to reflect energy back into space and retard
Which will happen? Well, nobody knows. The IPCC4 report admits
to not even knowing the sign of water's impact (e.g whether water is a
net positive or negative feedback) in these processes. And this is just
one example of the many, many feedback loops that scientists are able to posit
but not prove. And climate scientists are coming up with numerous other
positive feedback loops. As
one author put it:
Regardless, climate models are made interesting by
the inclusion of "positive feedbacks" (multiplier effects) so that a
small temperature increment expected from increasing atmospheric carbon dioxide
invokes large increases in water vapor, which seem to produce exponential
rather than logarithmic temperature response in the models. It appears to have
become something of a game to see who can add in the most creative feedback
mechanisms to produce the scariest warming scenarios from their models but
there remains no evidence the planet includes any such effects or behaves in a
Note that the majority of the warming in these models appears to be from
these feedback processes. Though it is hard to pick it out exactly,
section 8.6 of the fourth IPCC report seems to imply these positive feedback
processes increase temperature 2 degrees for every one degree from CO2.
This explains how these models get from a sensitivity of CO2 alone of about 1.0
to 1.5 degrees to a sensitivity of 3.5 or more degrees "“ it's all in the
So, is it reasonable to assume these feedback loops?
First, none have really been proven empirically, which does not of course
necessarily make them wrong. . In our daily lives, we generally deal
with negative feedback: inertia, wind resistance, friction are all negative
feedback processes. If one knew nothing else, and had to guess if a
natural process was governed by negative or positive feedback, Occam's razor
would say bet on negative. Also, we will observe in the next
section that when the models with these feedbacks were first run against
history, they produced far more warming than we have actually seen (remember
the analysis we started this section with "“ post-industrial warming implies
1-1.5 degrees sensitivity, not four).
Perhaps most damning is to ask, if this really is such a heavily positive
feedback process, what stops it? Remember the chart from earlier (show
again at the right), showing the long-term relationship of CO2 and
warming. Also remember that the data shows, and even AGW supporters
acknowledge, that temperature rises led CO2 rises by about 800 years.
Their explanation is that "something" caused the temperature to start
upwards. This higher temperature, as it warmed the oceans, caused CO2 to
outgas from the oceans to the atmosphere. Then, this new CO2 caused the
warming to increase further. In other words, outgassing CO2 from the
oceans was a positive feedback to the initial temperature perturbation.
In turn, the IPCC argues there are various other positive feedbacks that
multiply the effect of the additional warming from the CO2. This is
positive feedback layered on positive feedback. It would be like barely
touching the accelerator and having the car start speeding out o f control.
So the question is, if global temperature is built on top of so many positive
feedbacks and multipliers, what stops temperature form rising once it
starts? Why didn't the Earth become Venus in any of these events?
Because, for whatever else it means, the chart above is strong evidence that
temperature does not run away.
I have seen two suggestions, neither of which is compelling. The first
is that the oceans ran out of CO2 at some point. But that makes no
sense. We know that the oceans have far more CO2 than could ever be
liberated entirely to the atmosphere today, and besides, the record above
seems to claim that CO2 in the atmosphere never really got above there it was
say in 1880.
The second suggestion is based on the diminishing return relationship of CO2
to temperature. At some point, as I have emphasized many times, CO2's
ability to absorb infrared energy is saturated, and incremental quantities have
little effect. But note in the IPCC chart above, CO2 on the long time
scale never gets as high as it is today. If you argue that CO2's
absorption ability was saturated in earlier events, then you have to argue that
it is saturated today, and that incremental CO2 will have no further warming
effect, which AGW supporters are certainly NOT arguing. Any theory based
on some unknown negative feedback has to deal with the same problem: If
one argues that this negative feedback took over at the temperature peaks (in
black) doesn't one also have to argue that it should be taking over now at our
current temperature peak? The pro-AGW argument seems to depend on an assumption
of negative feedbacks in the past that for some reason can't be expected to
operate now or in the future. Why?
In fact, we really have not seen any evidence historically of these positive
feedback multipliers. As I demonstrated at the beginning of this chapter,
even assigning as much as 0.5C of the 20th century temperature
increase to CO2 only implies a sensitivity just over 1.0, which is about what
we would expect from CO2 alone with no feedbacks. This is at the heart of
problems with AGW theory "“ There is no evidence that climate sensitivity to CO2
is anywhere near large enough to justify the scary scenarios spun by AGW
supporters nor to justify the draconian abatement policies they advocate.
My tendency is to conclude that in fact, positive feedbacks do not dominate
climate, just as they do not dominate any long-term stable system. Yes,
certain effects can reasonably be said to amplify warming (ice albedo is
probably one of them) but there must exist negative feedbacks that tend to damp
out temperature movements. Climate models will never be credible, and
will always overshoot, until they start building in these offsetting forcings.
A funny thing happened when they first started running climate
models with high CO2 sensitivities in them against history: The models
grossly over-predicted historic warming. Again, remember our previous
analysis "“ historical warming implies a climate sensitivity between 1 and
1.5. It is hard to make a model based on a 3.5 or higher sensitivity fit
that history. So it is no surprise that one can see in the IPCC chart
below that the main model cases are already diverging in the first five years
of the forecast period from reality, just like the Superbowl predictors of the
stock market failed four years in a row. If the models are already high
by 0.05 degree after five years, how much will they overshoot reality over 100
In a large sense, this is why the global climate community has latched onto
the global dimming / aerosols hypothesis so quickly and so strongly. The
possible presence of a man-made cooling element in the last half of the 20th
century, even one that the IPCC fourth report ranks our understanding of as
"low," gives modelers a valuable way to explain why their models are
overstating history. The aerosols hypothesis is valuable for two reasons:
SO2 is prevalent today, but is expected to go down in the future, it allows
modelers to forecast much higher warming and climate sensitivity in the future
than has been observed in the past.
very lack of understanding of the amount, if any, of such aerosol cooling is
actually an advantage, because it allows modelers to set the value of such
cooling at whatever value they need to make their models work
I know the last statement seems unfair, but in reading the IPCC and other
reports, it appears to me that aerosol cooling values are set in exactly this
way "“ as what we used to call a "plug" figure between actual temperatures and
model output. While this may seem a chancy and fairly circular reasoning,
it makes sense for scientists because they trust their models. They
really believe the outputs are correct, such that any deviation is not
attributed to their assumptions about CO2 or climate sensitivity, but to other
But sulfates are not the only plug being used to try to make high
sensitivity models match a lower sensitivity past. You can see this in
the diagram below from the fourth IPCC report. This is their summary of
how their refined and tweaked models match history.
The blue band is without anthropogenic effects.
The pink band is with anthropogenic effects, including warming CO2 and cooling
aerosols. The black line is measured temperatures (smoothed out of
You can see the pink band which represents the models with anthropogenic
effects really seems to be a lovely fit, which should make us all
nervous. Climate is way too chaotic a beast to be able to model this
tightly. In fact, given uncertainties and error bars on our
historical temperature measurements, climate scientists are probably trumpeting
a perfect fit here to the wrong data. I am reminded again of a beautiful
model for presidential election results with a perfect multi-decadal fit based
on the outcome of NFL football games.
But ignoring this suspiciously nice fit, take a look at the blue bar.
This is what the IPCC models think the climate would be doing without
anthropogenic effects (both warming CO2 and cooling sulfates, for
example). With the peaked shape (which should actually be even more
pronounced if they had followed the mid-century temperature peak to its max)
they are saying there is some natural effect that is warming things until 1950
and then turns off and starts cooling, coincidently in the exact same year
that anthropogenic effects start taking off. I challenge you to read
the IPCC assessment, all thousand or so pages, and find anywhere in that paper
where someone dares to say exactly what this natural effect was, or why it
turned off exactly in 1950.
The reality is that this natural effect is another plug. There is no
actual empirical data to back up the blue line (in fact, as we will see in the
alternate theories section, there is good empirical data that this blue band is
wrong). Basically, climate scientists ran their models against history,
and found that even with their SO2 plug, they still didn't match well "“ they
were underestimating early century warming and over-estimating late century
warming. Remember that the scientists believe their models and their
assumptions about a strong CO2 effect, so they have modeled the non-anthropogenic
effect by running their models, tuning them to historical actuals, and then
backing out the anthropogenic forcings to see what is left. What is left,
the plug figure, is the blue line.
Already, the models used by the IPCC tend to overestimate past warming even
if all past warming is attributable to anthropogenic causes. If
anthropogenic effects explain only a fraction of past warming, then the current
models are vastly overstated, good for stampeding the populous into otherwise
unpopular political control over the economy, but of diminished scientific
The note I will leave you with is this: Do not gain false confidence
in the global climate models when they show you charts that their outputs run
backwards closely match history. This is an entirely circular argument,
because the models have been built, indeed forced, to match history, with
substantial plug figures added like SO2 effects and non-anthropogenic climate
trends, effects for which there are no empirical numbers.
If you walked into a room and found that it was too hot,
would you, as a first step:
- Measure the air to find anomalies in the mix of gasses
- Count the number of people in the room, to assess the effect
of body heat on the room's temperature
- Check the thermostat on the furnace
If you answered #3, sorry, but you can't join the
IPCC. If you really want to irritate an AGW supporter, ask about the
sun. To AGW supporters, only a Luddite would check the sun's output when
they could instead be obsessing over the increase in CO2 by 0.009% of the
When they looked at the problem, the IPCC decided that over
the last 50 years, the sun has been irrelevant to warming. Note that the
blue band in this chart (described in more detail in the last section), the
IPCC thinks that without man, the world would have cooled over the last 50
Further, when they detailed different climate forcings, the
forcing from changing solar irradiance was a trivial rounding error (though
they had the good grace to mark their understanding of this as "low") meaning
the sun has very little effect vs. what the sun had in 1850 (in the Little Ice
But it turns out, interestingly, that solar irradiance may be close to its
highest point in centuries. Al Gore says that current global temperatures
are the highest they have been in 1000 years. A new study by
the Institute of Astronomy in Zurich says that the "sun is more active now
than it has been at anytime in the previous 1,000 years." Related?
Sunspots have been monitored on the Sun since 1610,
shortly after the invention of the telescope. They provide the longest-running direct
measurement of our star's activity.
The variation in sunspot numbers has revealed the
Sun's 11-year cycle of activity as well as other, longer-term changes.
In particular, it has been noted that between about
1645 and 1715, few sunspots were seen on the Sun's surface.
This period is called the Maunder Minimum after the
English astronomer who studied it.
It coincided with a spell of prolonged cold weather
often referred to as the "Little Ice Age". Solar scientists strongly
suspect there is a link between the two events - but the exact mechanism
But the most striking feature, he says, is that
looking at the past 1,150 years the Sun has never been as active as it has been
during the past 60 years.
Over the past few hundred years, there has been a
steady increase in the numbers of sunspots, a trend that has accelerated in the
past century, just at the time when the Earth has been getting warmer.
The data suggests that changing solar activity is
influencing in some way the global climate causing the world to get warmer.
We can look at solar output over large time frames by
looking at the production of carbon-14 (less is produced in years of high solar
activity, and vice versa). The analysis below used the ratio of oxygen
isotopes in the stalagmites to estimate the water temperature at the time they
were formed. The result is an interesting correlation between solar
activity and a global temperature proxy over a long time-scale (Graph from Neff et al., 2001):
Over the last 1000 years, we see that (again using a
reversed scale of C14 as a proxy) solar activity is highly correlated with long
term temperature trends (I have used the pre-Mann chart, because while it may
over-emphasize the Medieval Warm Period, I still think such a period existed).
Look at the following reconstruction data by Judith Lean of
the Naval Research Library and charted from her data at NOAA by Junkscience.com
shows that interestingly, the sun's output does appear to be higher today than
they have been in many, perhaps hundreds of years
Would such increased activity be expected to result in
higher Earth temperatures? I don't know, and there are some issues one
has to be careful with on this chart. Most importantly the scaling:
While the shape of the curve looks a lot like the temperature trend over the
last 400 years, note that the entire variation from the low to the high point
is only about 0.25% "“ the scaling makes it look more dramatic. Of course,
the same could be said for global temperature, where a half degree C
temperature increase on an absolute Kelvin scale would only be about 0.17%, so
an argument can be made that on a percentage basis, this change in irradiance
is about the same order of magnitude as our change in temperature. A more
sophisticated comparison might say that since black body radiation is related
to absolute temperature to the fourth power, .25% increase in irradiance would
be expected to heat the Earth by .06%.
The chart on the above left compares the recent temperature
anomaly to solar irradiance, while the chart on the right compares it to CO2
concentrations. Neither is a beautiful fit (and one may have to include
aerosols in either scenario to account for 1970's cooling) but solar irradiance
seems at least as good as that of CO2. Remember, the IPCC shows
the world cooling due to solar effects during the same time the red solar
irradiance line is peaking.
Recently Alexander et. al. in have done some very comprehensive
work relating solar irradiance and rainfall. The study posits that one of
the reasons for less than perfect fit of sunspot and irradiance data with
temperature is that the Sun actually works on a 21 year cycle when the sunspot
cycle is combined with the cyclical wobble of the Suns motion through
space. The study concluded:
Intergovernmental Panel on Climate Change (IPCC) (2001) dismisses the view that
solar activity has a meaningful influence on global climate. The basis for this
view is that variations in the receipt of solar activity are too small to
account for variations in the climatic responses. These variations were
determined from satellite and other observations. What the IPCC scientists
failed to appreciate is that changes in the level of solar radiation received
on earth are amenable to precise calculation. The variations are well in excess
of the IPCC value of +0,3 Wm"“2 quoted earlier.
One of the interesting things about solar output is that, if
it is really higher, we should see effects on other planets, not just on
Earth. And, in fact, a lot of evidence has been pouring in over the last
5 years from astronomers (not climate guys) that the rest of the solar system
has been warming dramatically.
Mars, for example. Mar's ice caps have been melting and diminishing
since NASA's Mars Global Surveyor and Odyssey started to measure them around
Changes in the red spot on Jupiter
seem to be a sign of warming temperatures. And Neptunes moon Triton is
warming. We have to be careful with how we draw conclusions on these
outer planets, since their "year" is so long, seasonal changes can last
As seen in Figure 1, Neptune has been getting
brighter since around 1980; furthermore, infrared measurements of the planet
since 1980 show that the planet has been warming steadily from 1980 to 2004. As
they say on Neptune, global warming has become an inconvenient truth. But with
no one to blame, Hammel and Lockwood explored how variations in the output of
the Sun might control variations in the brightness of Neptune.
Figure 1 (a) represents the corrected visible light from Neptune from 1950 to
2006; (b) shows the temperature anomalies of the Earth; (c) shows the total
solar irradiance as a percent variation by year; (d) shows the ultraviolet emission
from the Sun (Source: Hammel and Lockwood (2007)).
What would seem so simple statistically is
complicated by the degrees of freedom in the various time series which is
related to the serial correlation in the data (e.g., next year's value is
highly dependent on this year's value). Nonetheless, they find that the
correlation coefficient between solar irradiance and Neptune's brightness is
near 0.90 (1.00 is perfect). The same relationship is found between the Earth's
temperature anomalies and the solar output. Hammel and Lockwood note "In other
words, the Earth temperature values are as well correlated with solar
irradiance (r = 0.89) as they are with Neptune's blue brightness (|r| >
0.90), assuming a 10-year lag of the Neptune values." The temporal lag is
needed to account for the large mass of Neptune that would require years to
adjust to any changes in solar output.
Hammel and Lockwood conclude that "In summary, if
Neptune's atmosphere is indeed responding to some variation in solar activity
in a manner similar to that of the Earth albeit with a temporal lag" then
"Neptune may provide an independent (and extraterrestrial) locale for studies
of solar effects on planetary atmospheres."
More on the sun's
variance and climate change here.
One of the problems with irradiance as a driver for climate
change is that though the changes seem to be fairly well correlated with the
temperature anomaly, many scientists think the magnitude is too small to
totally account for temperature changes. It is ironic that AGW supporters
use this as a refutation of the sun's effect, since they have exactly the same
problem with CO2, and must posit huge positive feedback loops to justify their
A second, newer theory has emerged as to a potential second
warming effect of solar output. To understand it, we have to start with
clouds. For those that don't live in a hot climate like I do here in
Phoenix, I will give everyone a bit of background "“ clouds cool things
off. Ok, as with everything in climate, things are actually far more
complicated "“ high clouds can sometimes cause warming, and nighttime clouds can
actually slow cooling. Never-the-less, in general, cloudcover cools things
off by blocking out and reflecting the sun's energy.
Clouds are in fact such a strong cooling force that is has
been estimated by several sources (Theodor Landscheidt, 1998) that having
clouds cover 1% more of the Earth's surface would cancel the heating effect of
a doubling of CO2. In fact, it was one of my criticisms earlier
that AGW theory seems overly intent on finding positive feedback loops, while
not considering negative feedbacks seriously enough "“ one such potential
negative feedback is that on a warmer Earth, more water is evaporated into
clouds, in turn cooling things back off.
But recently, an interesting new theory on cloud formation
has emerged. In short, it holds that cosmic rays, which are the high
energy particles that arrive at Earth from supernovas, spur cloud formation by
ionizing air molecules that act as seeds for water condensation and cloud
formation. This sounds wild, but really no wilder than warming by a gas
(CO2) that makes up a near trivial portion of the atmosphere. Like CO2 warming,
this effect has been observed in various laboratory chambers. But is it
really a measurable driver of climate?
Svensmark and Eigil Fris-Christensen looked at historic data on cloud cover
and cosmic ray incidence, from various measuring points. Their data was
extended and refined by Shiva in 2005.
So what changes cosmic ray flux to the Earth? The
biggest influence is the sun. When the sun's output is high, cosmic rays are
prevented from hitting the Earth, and vice versa. So high solar activity
corresponds to low cosmic ray flux and therefore lower cloud formation and
While the link between solar irradiance levels and warming
is pretty straight forward, the cosmic ray cloud formation proposition is still
in its infancy. Those of us who criticize AGW supporters for running past
the evidence on CO2 should not make the same mistake on cosmic rays, and movies
such as The Global Warming Swindle have gone too far in portraying this
alternate theory as fact.
Recently, Roger Pielke has done a substantial amount of
research on a different type of anthropogenic forcing. Specifically, he
has hypothesized that man's changing patterns of land use can be a substantial
driver of regional climate, including temperature and even more particularly,
precipitation. For example, clearing relatively dry land and
replacing it with irrigated agriculture substantially changes to the local heat
balance, not the least by increasing humidity. Dr. Pielke explains
summarizes the consequences on his web site:
Humans are significantly altering
the global climate, but in a variety of diverse ways beyond the radiative
effect of carbon dioxide. The IPCC assessments have been too conservative in
recognizing the importance of these human climate forcings as they alter
regional and global climate. These assessments have also not communicated the
inability of the models to accurately forecast the spread of possibilities of
future climate. The forecasts, therefore, do not provide any skill in
quantifying the impact of different mitigation strategies on the actual climate
that would occur.
One of the most fundamental premises of economics is that in a free society, an exchange or transaction only takes place when it benefits both the parties. Unfortunately, given how simple this axiom is and how easy it is to prove, it is either not accepted or not understood by a huge number of Americans. Thus we get any number of variations of the zero-sum wealth fallacy, and we get this, from Overlawyered:
A reader writes: "Am I wrong to believe that businesses and
consumers are natural enemies in that their economic interests are
Yes, you're wrong. Transactions don't occur unless both parties are
better off. Businesses thus only profit if they can create consumer
surplus"”the ability to sell a product at a price that is less than what
a consumer values the good or service. Businesses' interests are thus
aligned with consumers who seek consumer surplus. Businesses more often
prosper by creating satisfied consumers who become repeat customers who
promote the business's reputation rather than trying to extract every
last ounce of wealth from them in a single transaction. This is why
brand names and advertising are so important, because they are market
signals of long-term commitment to customer satisfaction. It's not
profitable to invest in creating a brand name if one intends on having
a bad reputation. (Note the key word "intends" there; no doubt one can
intend to have good customer service and fail to achieve it, and I'm
looking at you, Comcast.) And one will note that businesses that tend
not to have repeat customers or rely on word of mouth are more likely
businesses that have reputations of indifference about customer
satisfaction: tourist traps, traveling carnivals, etc.
A while back a made a purchase of a number of modular cabins for one of the campgrounds we operate. After the delivery, the sales person called me to thank me for my business. My reaction was "Thank me? I should be thanking you." The cabins are a huge boost to my business -- already I am getting great customer feedback -- and the modular technology saved me a ton of money on construction. See? Both the buyer and the seller were thrilled, because we were both better off.
I know a number of readers are tired of my writing about climate, so I am instead taking a shot at writing a comprehensive skeptic's argument on Anthropogenic Global Warming. A free pdf will be available for download next week, with a bound copy available for purchase at manufacturing cost.
In the mean time, LuboÅ¡ Motl presents one of the core skeptics arguments, that CO2 heat absorption is a diminishing return relationship to concentration, making frequent predictions of runaway climate scenarios a real head-scratcher.
In terms of numbers, we have already completed 40% of the task to
double the CO2 concentration from 0.028% to 0.056% in the atmosphere.
However, these 40% of the task have already realized about 2/3 of the
warming effect attributable to the CO2 doubling. So regardless of the
sign and magnitude of the feedback effects, you can see that physics
predicts that the greenhouse warming between 2007 and 2100 is predicted
to be one half (1/3 over 2/3) of the warming that we have seen between
the beginning of industrialization and this year. For example, if the
greenhouse warming has been 0.6 Celsius degrees, we will see 0.3
Celsius degrees of extra warming before the carbon dioxide
concentration doubles around 2100.
It's just like when you want
your bedroom to be white. You paint it once, twice, thrice. But when
you're painting it for the sixteenth time, you may start to realize
that the improvement after the sixteenth round is no longer that
If CO2 is not responsible for all the 0.6C of historic warming (a proposition for which there are good arguments) then future warming is even less. Read it all for more detail, or look for my paper next week which covers this topic and many, many others in more depth. There are lots of complications - aerosols, dimming, feedbacks - that are discussed in the paper.
I am writing a paper on climate models, and an important part of that discussion is on positive feedback (most climate models get large changes in future climate through the liberal use of positive feedback assumptions). I was looking around the Internet for a nice pithy explanation of positive feedback. This one on Wikipedia was fine, until I got wacked in the face with the last line (emphasis added)
The end result of a positive feedback is often amplifying
and "explosive." That is, a small perturbation will result in big
changes. This feedback, in turn, will drive the system even further
away from its own original setpoint, thus amplifying the original perturbation signal, and eventually become explosive because the amplification often grows exponentially
( with the first order positive feedback), or even hyperbolically (with
the second order positive feedback). An intuitive example is "the rich
get richer, and the poor get poorer."
Wow, intuitive? How can a statement that is wrong in at least two major ways be intuitive? First, the poor generally do not get poorer. In fact, the poor in the United States are in many ways better off than the richest men of the mid-nineteenth century (particular example linked is for the middle class, but many of the same arguments hold for the poor), and better off than the middle class of many nations. Second, while it might be arguable that there is a positive feedback loop that helps the rich get richer, no such loop is even possible with the very poorest. Without going into too much detail, the simplest explanation is that with income you can't go below zero. What people really mean by this statement is that the poor get poorer relative to the rich, rather than on an absolute scale. Which of course has little to do with positive feedback. By the way, the rest of the article is equally bizarre, giving more examples of social phenomena that are only weakly linked to positive feedback (Internet echo chamber effect?) rather than physical processes. It looks like a physics article written by a politics major.
Here are some alternative non-socialist examples of positive feedback from the physical world that actually have the virtue of being true: Nuclear fission, some exothermic chemical reactions, and acoustic feedback. In actuality, since positive feedback reactions are so explosive and unstable, they are very uncommon in nature, which is part of the argument against how climate models are constructed.
If you don't know the connection between climate models and positive feedback, see here.