Climate Feedback

Take all the psuedo-quasi-scientific stuff you read in the media about global warming.  Of all that mess, it turns out there is really only one scientific question that really matters on the topic of man-made global warming: Feedback.

While the climate models are complex, and the actual climate even, err, complexer, we can shortcut the reaction of global temperatures to CO2 to a single figure called climate sensitivity.  How many degrees of warming should the world expect for each doubling of CO2 concentrations  (the relationship is logarithmic, so that is why sensitivity is based on doublings, rather than absolute increases -- an increase of CO2 from 280 to 290 ppm should have a higher impact on temperatures than the increase from, say, 380 to 390 ppm).

The IPCC reached a climate sensitivity to CO2 of about 3C per doubling.  More popular (at least in the media) catastrophic forecasts range from 5C on up to about any number you can imagine, way past any range one might consider reasonable.

But here is the key fact -- Most folks, including the IPCC, believe the warming sensitivity from CO2 alone (before feedbacks) is around 1C or a bit higher (arch-alarmist Michael Mann did the research the IPCC relied on for this figure).  All the rest of the sensitivity between this 1C and 3C or 5C or whatever the forecast is comes from feedbacks (e.g. hotter weather melts ice, which causes less sunlight to be reflected, which warms the world more).  Feedbacks, by the way can be negative as well, acting to reduce the warming effect.  In fact, most feedbacks in our physical world are negative, but alarmist climate scientists tend to assume very high positive feedbacks.

What this means is that 70-80% or more of the warming in catastrophic warming forecasts comes from feedback, not CO2 acting alone.   If it turns out that feedbacks are not wildly positive, or even are negative, then the climate sensitivity is 1C or less, and we likely will see little warming over the next century due to man.

This means that the only really important question in the manmade global warming debate is the sign and magnitude of feedbacks.  And how much of this have you seen in the media?  About zero?  Nearly 100% of what you see in the media is not only so much bullshit (like whether global warming is causing the cold weather this year) but it is also irrelevant.  Entirely tangential to the core question.  Its all so much magician handwaving trying to hide what is going on, or in this case not going on, with the other hand.

To this end, Dr. Roy Spencer has a nice update.  Parts are a bit dense, but the first half explains this feedback question in layman's terms.  The second half shows some attempts to quantify feedback.  His message is basically that no one knows even the sign and much less the magnitude of feedback, but the empirical data we are starting to see (which has admitted flaws) points to negative rather than positive feedback, at least in the short term.  His analysis looks at the change in radiative heat transfer in and out of the earth as measured by satellites around transient peaks in ocean temperatures (oceans are the world's temperature flywheel -- most of the Earth's surface heat content is in the oceans).

Read it all, but this is an interesting note:

In fact, NO ONE HAS YET FOUND A WAY WITH OBSERVATIONAL DATA TO TEST CLIMATE MODEL SENSITIVITY. This means we have no idea which of the climate models projections are more likely to come true.

This dirty little secret of the climate modeling community is seldom mentioned outside the community. Don’t tell anyone I told you.

This is why climate researchers talk about probable ranges of climate sensitivity. Whatever that means!…there is no statistical probability involved with one-of-a-kind events like global warming!

There is HUGE uncertainty on this issue. And I will continue to contend that this uncertainty is a DIRECT RESULT of researchers not distinguishing between cause and effect when analyzing data.

If you find this topic interesting, I recommend my video and/or powerpoint presentation to you.

  • http://lwolt.wordpress.com/ Larry Sheldon

    What causes the polarity of the sensitivity to toggle, as we are seeing it do at the moment?

    (The CO2 concentration marches on up along a pretty linear line, while temperature flails about almost as if it was not correlated with CO2 concentration.)

  • Mesa Econoguy

    Audio engineers understand feedback concepts very well.

    Small rooms, quick slapback, anything which causes rapid, immediate reverberation or amplified input into mikes or stage amps.

    Tree rings spliced with ice cores are complete bullshit proxies for temperature measurements.

    That's like splicing stock charts from Berkshire A in the 1980s with Cisco or Microsoft or JDS Uniphase in the 1990s .

    You'd be arrested for that, courtesy of our new, more powerful SEC.

    I'm interested in Gavin the Punk's 1 year, 5 year, and 10 year returns, under 10b5 guidelines...

  • Highway

    Larry, it's not that the polarity of the sensitivity will change. If the feedback is negative, then it will damp climate changes in both directions. If the feedback is positive, then it will amplify climate changes in both directions.

    There are also likely floor and ceiling effects. Like the earth can't get so cold that everything freezes solid, because of the molten core and the position in the solar system. Likewise, it can't get so hot because there's only the sun providing energy into the system, and it will radiate some energy no matter what. But those aren't really in the range of anything we'd want to discuss.

  • Highway

    Understanding your comment more: The reason that climate seems only indirectly related to CO2 concentration is because it is. There are so many other variables in the analysis that greenhouse effects are only a minor part of it. And that's why there's this huge debate about it.

  • http://harries@free.fr blokeinfrance

    So if noone has a handle on the science, the debate can't be about The Science.
    Maybe it's about The Money? As in "Pay up now or your grandchild gets it".

  • Dr. T

    I am irked by numerous unsupported climatology claims, but the greenhouse gas effect is the most annoying. There has NEVER been a study showing that the greenhouse gas effect has ANY relevance to climate or weather. If concentrations of greenhouse gases increase in the atmosphere, we have no idea whether global temperatures will increase, decrease, or be unchanged.

    How can this be? The greenhouse gas effect is based on the physical chemistry of gas molecules. A molecular bond can absorb a photon (of a specific energy) and convert some or all of the photon's electromagnetic energy into bond vibrational energy. Increased bond vibrational energy increases temperature. But remember that each type of bond can only absorb photons of specific energies. If, for example, the concentration of atmospheric methane increases, then there will be increased absorption of specific-energy photons throughout the atmosphere: from fifty miles up in the mesosphere down to the surface. Methane molecules that absorb photons in the lower atmosphere will generate warming, but those that absorb photons in the upper atmosphere will have no effect on global temperatures. If the increased numbers of methane molecules in the upper atmosphere absorb many of the specific-energy photons from the sun, then it is possible that methane's greenhouse gas effect will be DECREASED in the lower atmosphere. This would cause cooling rather than warming.

    Even if the increased absorption of specific-energy photons in the upper atmosphere does not block greenhouse gas effects in the lower atmosphere, there still is no evidence that greenhouse gas-related warming will be immune to feedback changes. For example, if carbon dioxide concentrations rise greatly and the lower atmosphere gets warmer, then surface water evaporation will increase and cloud formation will increase. Because the atmosphere is warmer, water vapor will rise higher before condensing into clouds. High clouds increase planetary albedo, which means that more solar energy is reflected away before reaching the surface. This cools the planet and returns temperatures to "normal." This easily understood feedback system was NOT incorporated into the 25 (failed) climate models submitted to the IPCC and is NOT a part of the fudged-up climate meta-model the IPCC promulgates. The entire claim of anthropogenic global warming due to increased carbon dioxide is baseless.

  • Roy Lofquist

    There ain't no such thing as a "greenhouse effect".

    http://www.natscience.com/Uwe/Forum.aspx/physics/22563/Greenhouse-Physics

  • Gil

    So greenhouses are a waste to time too?

  • Roy Lofquist

    Gil,

    No, greenhouses work - but not for the reasons assumed by warmists. Primarily, they prevent convection - hot to cold, first law of thermodynamics. Fourier was speculating. Wood proved him wrong experimentally. Don't mention experiment to warmists. It make them nervous.

    Roy

  • Bearster

    Dr. T is right. CO2 acts by allowing the higher-frequency energy of the sun's rays to hit the earth, but blocking the lower-frequency rays that the earth emits.

    Warren: there is another effect that suggests that the theoretical temperature difference for increased CO2 should be *sub* linear, or even asymptotic. Saturation. It's like putting red cellophane on your window. Each layer makes the view a little more red until you saturate and it does not get more red because 100% of the non-red wavelengths are absorbed. Steven Malloy of junkscience.com discusses this effect.

    But anyways, I want to levy a 50% tax on your business and please pay in cash net 7. Thank you for doing your part to reduce the world's temperature!

  • Dr. T

    For Gil: The greenhouse effect was described in decades-old studies of greenhouse efficiency. The studies used air-tight greenhouses and varied temperature, humidity, and carbon dioxide concentrations. Optimum temperature was approximately 100 degrees Fahrenheit. Optimum humidity was 90-100%. The high humidity had two benefits: it reduced water evaporation from plants, and it made it cheaper to heat the greenhouses. (Water vapor is good greenhouse gas: its two single-bonds readily absorb solar energy and convert some of it to heat.) Increasing the carbon dioxide levels (to 2-5 times normal) improved plant growth (because photosynthetic plants use carbon dioxide as a fuel and as a building block for sugars, starches, and other hydrocarbons). The studies also showed that increased carbon dioxide concentrations lowered heating costs, but not nearly as much as raising humidity. CO2 is a mediocre greenhouse gas (its double-bonds require much higher energy photons than the single-bonds in water, and the solar spectrum at ground level doesn't have as many higher energy photons).

    The reasons why today's greenhouses do not crank up CO2 concentrations are: 1. Air-tight greenhouses are expensive, 2. It costs money to pipe in CO2, 3. Workers would need to wear respirators, 4. The increased rate of plant growth due to more CO2 was not huge, and 5. The heating cost reductions from CO2 increases were orders of magnitude less than the increased costs of items 1, 2, and 3.

  • IgotBupkis, President, United Anarchist Society

    testing ignore this post.