Breaking News: Recent US Temperature Numbers Revised Downwards Today

This is really big news, and a fabulous example of why two-way scientific discourse is still valuable, in the same week that both Newsweek and Al Gore tried to make the case that climate skeptics were counter-productive and evil. 

Climate scientist Michael Mann (famous for the hockey stick chart) once made the statement that  the 1990's were the
warmest decade in a millennia and that "there is a 95 to 99% certainty
that 1998 was the hottest year in the last one thousand years." (By
the way, Mann now denies he ever made this claim, though you can watch him say
these exact words in the CBC documentary Global
Warming:  Doomsday Called Off
).

Well, it turns out, according to the NASA GISS database, that 1998 was not even the hottest year of the last century.  This is because many temperatures from recent decades that appeared to show substantial warming have been revised downwards.  Here is how that happened (if you want to skip the story, make sure to look at the numbers at the bottom).

One of the most cited and used historical surface temperature databases is that of NASA/Goddard's GISS.  This is not some weird skeptics site.  It is considered one of the premier world temperature data bases, and it is maintained by anthropogenic global warming true believers.  It has consistently shown more warming than any other data base, and is thus a favorite source for folks like Al Gore.  These GISS readings in the US rely mainly on the US Historical Climate Network (USHCN) which is a network of about 1000 weather stations taking temperatures, a number of which have been in place for over 100 years.

Frequent readers will know that I have been a participant in an effort led by Anthony Watts at SurfaceStations.org to photo-document these temperature stations as an aid to scientists in evaluating the measurement quality of each station.  The effort has been eye-opening, as it has uncovered many very poor instrument sitings that would bias temperature measurements upwards, as I found in Tucson and Watts has documented numerous times on his blog.

One photo on Watt's blog got people talking - a station in MN with a huge jump in temperature about the same time some air conditioning units were installed nearby.   Others disagreed, and argued that such a jump could not be from the air conditioners, since a lot of the jump happened with winter temperatures when the AC was dormant.  Steve McIntyre, the Canadian statistician who helped to expose massive holes in Michael Mann's hockey stick methodology, looked into it.  After some poking around, he began to suspect that the GISS data base had a year 2000 bug in one of their data adjustments.

One of the interesting aspects of these temperature data bases is that they do not just use the raw temperature measurements from each station.  Both the NOAA (which maintains the USHCN stations) and the GISS apply many layers of adjustments, which I discussed here.  One of the purposes of Watt's project is to help educate climate scientists that many of the adjustments they make to the data back in the office does not necessarily represent the true condition of the temperature stations.  In particular, GISS adjustments imply instrument sitings are in more natural settings than they were in say 1905, an outrageous assumption on its face that is totally in conflict to the condition of the stations in Watt's data base.  Basically, surface temperature measurements have a low signal to noise ratio, and climate scientists have been overly casual about how they try to tease out the signal.

Anyway, McIntyre suspected that one of these adjustments had a bug, and had had this bug for years.  Unfortunately, it was hard to prove.  Why?  Well, that highlights one of the great travesties of climate science.  Government scientists using taxpayer money to develop the GISS temperature data base at taxpayer expense refuse to publicly release their temperature adjustment algorithms or software (In much the same way Michael Mann refused to release the details for scrutiny of his methodology behind the hockey stick).  Using the data, though, McIntyre made a compelling case that the GISS data base had systematic discontinuities that bore all the hallmarks of a software bug.

Today, the GISS admitted that McIntyre was correct, and has started to republish its data with the bug fixed.  And the numbers are changing a lot.  Before today, GISS would have said 1998 was the hottest year on record (Mann, remember, said with up to 99% certainty it was the hottest year in 1000 years) and that 2006 was the second hottest.  Well, no more.  Here are the new rankings for the 10 hottest years in the US, starting with #1:

1934, 1998, 1921, 2006, 1931, 1999, 1953, 1990, 1938, 1939

Three of the top 10 are in the last decade.  Four of the top ten are in the 1930's, before either the IPCC or the GISS really think man had any discernible impact on temperatures.  Here is the chart for all the years in the data base:
New_giss

There are a number of things we need to remember:

  • This is not the end but the beginning of the total reexamination that needs to occur of the USHCN and GISS data bases.  The poor correction for site location and urbanization are still huge issues that bias recent numbers upwards.  The GISS also has issues with how it aggregates multiple stations, apparently averaging known good stations with bad stations a process that by no means eliminates biases.  As a first step, we must demand that NOAA and GISS release their methodology and computer algorithms to the general public for detailed scrutiny by other scientists.
  • The GISS today makes it clear that these adjustments only affect US data and do not change any of their conclusions about worldwide data.  But consider this:  For all of its faults, the US has the most robust historical climate network in the world.  If we have these problems, what would we find in the data from, say, China?  And the US and parts of Europe are the only major parts of the world that actually have 100 years of data at rural locations.  No one was measuring temperature reliably in rural China or Paraguay or the Congo in 1900.  That means much of the world is relying on urban temperature measurement points that have substantial biases from urban heat.
  • All of these necessary revisions to surface temperatures will likely not make warming trends go away completely.  What it may do is bring the warming down to match the much lower satellite measured warming numbers we have, and will make current warming look more like past natural warming trends (e.g. early in this century) rather than a catastrophe created by man.  In my global warming book, I argue that future man-made warming probably will exist, but will be more like a half to one degree over the coming decades than the media-hyped numbers that are ten times higher.

So how is this possible?  How can the global warming numbers used in critical policy decisions and scientific models be so wrong with so basic of an error?  And how can this error have gone undetected for the better part of a decade?  The answer to the latter question is because the global warming  and climate community resist scrutiny.  This weeks Newsweek article and statements by Al Gore are basically aimed at suppressing any scientific criticism or challenge to global warming research.  That is why NASA can keep its temperature algorithms secret, with no outside complaint, something that would cause howls of protest in any other area of scientific inquiry.

As to the first question, I will leave the explanation to Mr. McIntyre:

While acolytes may call these guys "professionals", the process of
data adjustment is really a matter of statistics and even accounting.
In these fields, Hansen and Mann are not "professionals" - Mann
admitted this to the NAS panel explaining that he was "not a
statistician". As someone who has read their works closely, I do not
regard any of these people as "professional". Much of their reluctance
to provide source code for their methodology arises, in my opinion,
because the methods are essentially trivial and they derive a certain
satisfaction out of making things appear more complicated than they
are, a little like the Wizard of Oz. And like the Wizard of Oz, they
are not necessarily bad men, just not very good wizards.

For more, please see my Guide to Anthropogenic Global Warming or, if you have less time, my 60-second argument for why one should be skeptical of catastrophic man-made global warming theory.

Update:
Nothing new, just thinking about this more, I cannot get over the irony that in the same week Newsweek makes the case that climate science is settled and there is no room for skepticism, skeptics discover a gaping hole and error in the global warming numbers.

Update #2:  I know people get upset when we criticize scientists.  I get a lot of "they are not biased, they just made a mistake."  Fine.  But I have zero sympathy for a group of scientists who refuse to let other scientists review their methodology, and then find that they have been making a dumb methodology mistake for years that has corrupted the data of nearly every climate study in the last decade.

Update #3:  I labeled this "breaking news," but don't expect to see it in the NY Times anytime soon.  We all know this is one of those asymmetric story lines, where if the opposite had occurred (ie things found to be even worse/warmer than thought) it would be on the front page immediately, but a lowered threat will never make the news.

Oh, and by he way.  This is GOOD news.  Though many won't treat it that way.  I understand this point fairly well because, in a somewhat parallel situation, I seem to be the last anti-war guy who treats progress in Iraq as good news.

Update #4: I should have mentioned that the hero of the Newsweek story is catastrophic man-made global warming cheerleader James Hansen, who runs the GISS and is most responsible for the database in question as well as the GISS policy not to release its temperature aggregation and adjustment methodologies.  From IBD, via CNN Money:

Newsweek portrays James Hansen, director of NASA's Goddard Institute for Space Studies, as untainted by corporate bribery.

Hansen
was once profiled on CBS' "60 Minutes" as the "world's leading
researcher on global warming." Not mentioned by Newsweek was that
Hansen had acted as a consultant to Al Gore's slide-show presentations
on global warming, that he had endorsed John Kerry for president, and
had received a $250,000 grant from the foundation headed by Teresa
Heinz Kerry.

Update #5: My letter to the editor at Newsweek.  For those worried that this is some weird skeptic's fevered dream, Hansen and company kind of sort of recognize the error in the first paragraph under background here.  Their US temperature chart with what appears is the revised data is here.

Update #6: Several posts are calling this a "scandal."  It is not a scandal.  It is a mistake from which we should draw two lessons:

  1. We always need to have people of opposing opinions looking at a problem.  Man-made global warming hawks expected to see a lot of warming after the year 2000, so they never questioned the numbers.  It took folks with different hypotheses about climate to see the jump in the numbers for what it was - a programming error.
  2. Climate scientists are going to have to get over their need to hold their adjustments, formulas, algorithms and software secret.  It's just not how science is done.  James Hansen saying "trust me, the numbers are right, I don't need to tell you how I got them" reminds me of the mathematician Fermat saying he had a proof of his last theorem, but it wouldn't fit in the margin.  How many man-hours of genius mathematicians was wasted because Fermat refused to show his proof (which was most likely wrong, given how the theorem was eventually proved).

Final Update:  Some parting thoughts, and recommendations, here.

  • http://ugleenakedguy.blogspot.com UGN

    I tagged you for one of those thingys. I have never done it before. Hope that doesn't annoy you.

  • http://libertarianlifter.blogspot.com Paul

    Anyone else see a remarkable parallel between global warming skeptics and Evolutionists?

    The Global Warming Religion BELIEVES. The skeptics use the scientific method and facts to determine what's really happening. The Global Wrming Zealots yell and scream that the skeptics are heretics.

    It was hot as blazes yesterday, though. I wonder if it was my fault.

  • http://www.isaharr.com Isaac Crawford

    I wonder if a FOI request would help in these sorts of things?

    Isaac

  • atr

    There's a big difference between this good news and good news regarding the war. Bad news on the climate is used to justify more government intervention, but bad news from Iraq will likely increase pressure to withdraw U.S. forces.

  • John Dewey

    Thanks, Warren, for this and all the other insights you've provided us about Global Warming "science". You've energized me to write a few letters.

  • dan

    so how does this explain all the rising water levels and degrading ice floes and specfics which i cannot off the top of my head remember, about how the climate change is affecting polar bears hunting patterns, etc.?

    you talk as if the whole damn theory is based on these numbers. fortunately, people better at this than you are working on this.

  • Jim Howe

    The important thing to remember is that this data is used to feed computer models which are in turn used to project future climate behavior. Change the input and the models produce different results. A model is only as good as it's data and if this data is suspect, who is to say that other data isn't equally suspect?

  • dearieme

    Congratulations to Mr McIntyre. I only wish he were British - Sir Steven McIntyre has a fine ring to it. Congrats to you too; and to all the paparazzi of the weather stations. Well done, chaps. It has been reading writers like you that finally persuaded me some weeks ago that I was no longer a Global Warming Sceptic - I had become a Global Warming Cynic. "Government scientists ..refuse to publicly release their temperature adjustment algorithms or software": the default interpretation of that is that they are crooks.

  • Anonymous

    fortunately, people better at this than you are working on this

    Unknown people better than you in unknown features are working on this in unspecified ways.

    Oh yeah, and it benefits them personally by more grant money and more prominence.

    No reason to worry here.

  • wssea

    DO you also dispute the validity of other data provided at http://data.giss.nasa.gov/gistemp/graphs/, such as the "Annual Mean Temperature Change for Hemispheres"?

  • Funky Disposition

    I would argue that the earth is to complex to have a temperature, let alone an average temperature. Are you using arithmetic or geometric averaging, you had better know the difference.

    The earth has many temperatures, everyplace there is a thermometer there is a temperature, but what is the temperature between thermometers? ... This is where the problem of averaging comes in...

    To pretend that the earth even has a temperature is voodoo.

    if it is 70 degrees here and 5 miles away it is 75 degrees then how do you measure an average temperature ... assume that at 2.5 miles the temperature is 72.5.

    The recorded earth temperatures are only valid for averaging the temperature of weather stations, not the landscape between ... all that swirling air of different temperatures is not measurable under current practices ... and may never be.

    The hoax is this, that the earth even has a temperature average that can be pinned down to a number.

    The globe has been warming since the last ice age 10,000 years ago; back when the glaciers reached down into Indiana ... they have been receding since.

    Heck, if it is not receding then is proceeding. If it is not moving, then it is not a glacier, it is an ice field. Glaciers move, ergo, receding is natural in a dynamic world.

  • runemonger

    Very good posting, Funky Dispo. well done!

  • Byron

    When we moved to Santa Fe, the city rarely recorded a temperature above 90 degrees. Now those temps are common. But not many years ago, I understand that the temperature recording site was moved from an in-town location out to the airport, where it's hotter. Obviously, this has caused the global temperature to rise. I think they should move their thermometer back into town. Seems little enough to ask to save the planet.

  • Byron

    Well, I sure hope nobody thinks this kind of thing should be allowed in any way to affect the Consensus, because this issue has already been decided. It's all worked out a hundred years into the future to the third decimal place. Magic of science!

    But this is a nuisance. Muddies the water. So, clearly, the challenge now is to come up with a bulletproof climate prediction model, one so robust that data changes cannot affect the results! No matter what data you plug in, the model will grind out the very same predictions of global catastrophe -- a sort of climatological Final Solution, eliminating all the skeptics and nay-sayers, once and for all. Sweet!

    Then Al Gore can be anointed King of the World, and we can all live happily ever after.

  • Christoph

    so how does this explain all the rising water levels and degrading ice floes and specfics which i cannot off the top of my head remember, about how the climate change is affecting polar bears hunting patterns, etc.?

    you talk as if the whole damn theory is based on these numbers. fortunately, people better at this than you are working on this.

    Posted by: dan | Aug 9, 2007 11:19:09 AM

    dan, you walking parody.

  • Christoph

    so how does this explain all the rising water levels and degrading ice floes and specfics which i cannot off the top of my head remember, about how the climate change is affecting polar bears hunting patterns, etc.?

    you talk as if the whole damn theory is based on these numbers. fortunately, people better at this than you are working on this.

    Posted by: dan | Aug 9, 2007 11:19:09 AM

    dan, you walking parody.

  • JoeBloe

    These are temperature records for the UNITED STATES.

    They are NOT temperature records for an assessment of overall GLOBAL WARMING.

    "Well, it turns out, according to the NASA GISS database, that 1998 was not even the hottest year of the last century."

    in the UNITED STATES.

    Sheesh.
    If you want to play the game of fact-checking others, maybe you should start with yourself.

  • TheBigOldDog

    Can you tell me if anyone has filed a freedom of information request and/or law suit to force the release the methodology, computer algorithms and raw data? If not, why not? Are they not governed by the same laws as any tax payer funded government agency?

  • Neuro-conservative

    Thank you for your efforts! I want to present these results to some blogging adversaries I have on the internets, but I want to be prepared. What would be your response if they say that this effect is U.S. only and does not substantially affect global trends?

  • Bill

    Actually JoeBloe and Neuro-conservative, If you read his post carefully you'd see he already answered you.

    Short version- there aren't reliable temperature readings for most of the world going back 100 years. The US records are the most complete and reliable, and even those have some serious methodological problems, as he discussed.

    Bill

  • Papertiger

    I believe there was some sort of problem involving Steve McIntyre filing an FOI because he is Canadian. Perhaps you could file one on his behalf. I don't know the legalities.

  • http://pworld.thestateonline.com Mike Cakora

    Methinks some folks are missing the “science” aspect to all of this. Folks have examined the various data analyses and hypotheses put forth for public consumption and have developed some new and valuable information about instrumentation (collections station siting and calibration) and procedures (algorithms) that should be introduced into new and improved hypotheses for others to examine.

    This ain’t politics wherein one argues policy and preference with nary the occasional glance at data, but rather in principle a shared activity where all open their kimonos to reveal the substance behind the contours.

    Bravo! Let us all see the naked truth, as unpleasant as it may be.

  • Anonymous

    Lol, propaganda.

  • MikeM

    Thanks for bringing this information to our attention. Elsewhere in the comments section someone points out that water is indeed rising and floods are occuring. I believe the explanation is - at least partly - due to the abundance of data related to the weather and climatic pertubations that we never had even 10 years ago. We hear now of floods in Asia and Africa, heat and drought in Australia, melting ice everywhere and the mind connects the dots and concludes warming evidence is everywhere. Of course, these are normal climatic fluctuations that have always gone on, but now thanks to the plethora of weather data from places we have hardly heard of, we see evidence of global warming in every weather event.

  • cpurick

    Thank you for calling attention to the good news/bad news problem.

    The prospect of mankind somehow wrecking the climate would be a disaster. One would expect any rational person to be relieved to learn that things might not be as bad as they feared.

    But to the global warming whack-jobs, this sort of news is "bad." What does it say about a segment of society that wants the worst for us???

  • Kralizec

    Their US temperature chart with what appears is the revised data is here.

    I just got a blank page back from that URL.

  • Kralizec

    However, I found the PDF available just now.

    http://data.giss.nasa.gov/gistemp/graphs/Fig.D.pdf

  • Brassy Rich

    Looks like graph is still going up. Who cares which year was hotter than the others?

  • Brassy Rich

    Looks like graph is still going up. Who cares which year was hotter than the others?

  • Kralizec

    That is why NASA can keep its temperature algorithms secret, with no outside complaint, something that would cause howls of protest in any other area of scientific inquiry.

    A comparable situation seems to exist in regard to release of the genetic sequences of H5N1 "avian" influenza particles from newly infected humans and animals. Much of the commentary at the following URL includes mention of the author's frustration by the secrecy.

    http://www.recombinomics.com/whats_new.html

  • Chris Chittleborough

    Steve McIntyre's blog, http://climateaudit.org, has been hammered into silence by a DDOS attack. The attack was launched just after this story broke. It would be fascinating to know who instigated it.

    BTW, McIntyre is not a skeptic about global warming in general, nor about that warming being caused by human activity. His skepticism is focused on the activities of a few climate "scientists".

  • rufus

    A "Market-Player" might look at that chart and say, "Hmm, Double-Top Forming?"

  • pt314

    "Oh yeah, and it benefits them personally by more grant money and more prominence."

    This is a big part of science, and the training begins early. Starting in my sophomore year the professors started telling us how to game the system to appeal to the prejudices and fears of those controlling grant money.

    And as a number of scientists have pointed out, when money (and ideology) are at stake, truth takes a back seat...and sometimes gets hit over the head and stuffed in the trunk.

  • Tony

    Well done. It never ceases to amaze me that there is a problem with the temp data. I have seen some of those monitoring stations and their placement defies all of the rules.

    I wonder what these GW folks are going to say when our sun starts to turn red and get a whole lot bigger? Although we do have about a tad less than a billion years to wait for that particular event to happen....

  • http://porkopolis.blogspot.com Porkopolis

    Last year I had a detailed post on how 60 Minutes conveniently left out the details that a scientist (Paul Mayewski) featured on their broadcast to support the global warming position also published contradictory evidence:

    "A team led by University of Maine scientists has reported finding a potential link between changes in solar activity and the Earth's climate. In a paper due to be published in an upcoming volume of the Annals of Glaciology, Paul Mayewski, director of UMaine's Climate Change Institute, and 11 colleagues from China, Australia and UMaine describe evidence from ice cores pointing to an association between the waxing and waning of zonal wind strength around Antarctica and a chemical signal of changes in the sun's output..."

  • http://www.mothering.com/discussions/forumdisplay.php?f=44 Acksiom

    I wonder if Google would be interested in distributing wireless thermometers to the general public in order to add temperature 'elevations' to their Maps service.

    Heck, maybe even wireless micro-weatherstations.

  • Jim Lindgren

    John writes:

    "so how does this explain . . . how the climate change is affecting polar bears hunting patterns, etc.?"

    John, are you referring to the phony claims and bogus photos of environmentalists Al Gore and Tim Flannery about the impending extinction of polar bears. Canadian polar bear expert Mitchell Taylor writes:

    Climate change is having an effect on the west Hudson population of polar bears, but really, there is no need to panic. Of the 13 populations of polar bears in Canada , 11 are stable or increasing in number. They are not going extinct, or even appear to be affected at present.

    It is noteworthy that the neighbouring population of southern Hudson Bay does not appear to have declined, and another southern population ( Davis Strait ) may actually be over-abundant.

    I understand that people who do not live in the north generally have difficulty grasping the concept of too many polar bears in an area. People who live here have a pretty good grasp of what that is like to have too many polar bears around.

    For background, see:

    http://timblair.net/ee/index.php/weblog/polarganda/

    http://meteo.lcd.lu/globalwarming/Taylor/last_stand_of_our_wild_polar_bears.html

  • PSGInfinity

    Dan @ 11:19 asked:

    "so how does this explain all the rising water levels and degrading ice floes ..."

    Dan, have you ever seen photos of retreating glaciers? Every time I see one, I'm struck by how dirty it is. I think the glaciers are receding due to *soot pollution* more than CO2 emissions. I'm not a scientist, and don't feel like running an experiment, but I would keenly like to see one done.

    Any grad students out there?

  • http://powerandcontrol.blogspot.com/ M. Simon

    Dan,

    I worry about rising water level too. Latest estimates are that sea level is rising 1.5 mm a year. That is 6" in a century. Run for your lives.

    I predict that people whose heads are only 6" above water and don't move for a century will be drowned. We must spend hundreds of trillions to prevent this catastrophe.

    And what about the polar bears? Global warming has so improved their habitat that their population is rising. If this keeps up they will eat all our children. Something must be done. At once!

  • http://market-factors.blogspot.com/ M-F

    Very, very interesting post. Keep up the fantastic work.

    Computer programmers & those who design them make mistakes all the time.

    The "science is settled/arguement is over" coment from Gore is horribly undemocratic. It's purpose is to stifle debate and dissent and critical thinking.

    I do believe America should be heading towards electric cars for energy independence and national security reasons. But, we should not harm our currently very fragile ecomony with any enery policy which makes us less competitive. It wold be nice to have an energy policy though, aimed at independence.

    We have a lot of "group-think" in the financial markets as well. People should know better than to blindly go with the crowd, but they do, and lose billions. Keep up the critical thinking, it is in short supply!

  • http://powerandcontrol.blogspot.com/ M. Simon

    The area of the United States is 38 million square miles. Let us assume having a temperature measuring unit every 10 miles is good enough to get an average. That would require 380,000 quality measuring points. Currently there are 1221 monitoring stations. Some have been found to be of low quality, when high quality was assumed.

  • http://lefthandpalm.blogspot.com/ lurgee

    I don't see what all the fuss is about.

    The 1930s were hot. this was already known. The 1990s were hot. This was already known. Previously, it was thought the 1998 was the hottest year, by a slender margin. Now the revised data shows it was the second hottest, by a very slender margin.

    This doesn't prove anything beyond that. It does not prove that there is not overall global warming in the latter half of the 20th century, and it does not prove that humans aren't responsible for it.

  • http://thenorthcave.blogspot.com Sir Sefirot

    It doesn't prove that humans ARE responsible for it neither. There is little question about the warming, but, there was also warming from 1900 to the 1930s, and after that temperatures cooled. Even assuming than the CO2 emissions are human-caused (which they are only in approximately 1%) this temperatures don't correspond to the CO2 records. At all.

    Have you ever heard of cosmic rays, lurgee? And I don't mean the mental-control ones.

    Watch this and you may learn something.
    http://stage6.divx.com/user/angkorwat/video/1348005/El-gran-timo-del-calentamiento-global-(VOS-Spanish)

    I swear, if I hear another GW fanatic I'm going to puke. For the love of god, get yourself some studies!

  • Rob

    LOL. I used to think World War 3 would be one of economics leading to physical conflict ... maybe it WW3 will be started by the environmentalists.

    Why not? "IF" (for the sake of argument), we assume that any pollution I do has a harmful affect on everyone in the world since they are all impacted by the global climate, then shouldn't anyone from this planet be able to stop me?

    For example, if someone is going to kill you, then they are violating your natural rights. This is to say that their rights end where yours begin, so in affect, they have lost their right to live because they have proceeded in trying to take your life.

    Here's the question I'd like a response to (why or why not):
    If a country like China wants to continue allowing pollution, then wouldn't the rest of the world be in its right to go destroy China (ie. WW3)? Why wouldn't we stop a country who's policy is destroy the Earth?

    Furthermore, shouldn't the rest of the world that polluted (before we knew it was bad), be responsible to give China retribution payments? Since the rest of the world made improved its standard of living, then the rest of the world should sacrifice until China is on an equal level (assuming they had been allowed to pollute for a century)?

  • Boris

    "Well, it turns out, according to the NASA GISS database, that 1998 was not even the hottest year of the last century."

    This is incorrect, as has been pointed out. NASA corrected their error immediately. Why have you refused to correct this error?

  • Southern gal

    Question: weren't there recent studies of ice cores from glaciers around the world that showed that the temperatures of the Medieval Warm Period were higher than our temperatures today?

    I mean, people growing oranges and grapes in York, England should have been a clue (unfortunately, not many records of produce have survived from that period.)

    Where were their cars and planes and factories? We're talking about a feudal system before electricity, large scale manufacturing, and automation. I don't think we have a whole lot to worry about.

  • Thai

    Boris - NASA corrected it after they got caught with bad data. His post was correct.

  • Thaiphoon

    [i]This doesn't prove anything beyond that. It does not prove that there is not overall global warming in the latter half of the 20th century, and it does not prove that humans aren't responsible for it.[\i]

    I certainly HOPE the Earth has been warming in the latter part of the 20th century. Otherwise it would be cooling !! We're coming out of the last Ice Age and as such I'd expect us to be warming. Otherwise we'd be in big trouble. CO2 is not even a strong greenhouse gas...and humans emit less than 5% of it each year (the oceans release over 95% of the CO2 in the Earth's atmosphere each year). So please - save your sermons about my "carbon footprint".

  • mz

    Misleading commentary as it's not mentioned that only US temperatures changed, which have about 1/50 effect on the total world average.
    So the blog pretends that Mann said something about the US temperature (which now has been changed a tiny bit), when he was talking about the WORLD.

    For some reasons most of the commenters get their facts completely wrong too.

    Lousy blog, lousy commenters, stop reading this crap people.

  • Walt Donaldson

    Historial data is still useful. Look at the English weather in the last 1,900 years or so, which predates much of the so called Anthropogenic CO2 production which is infinitesimal in comparison to Mother Nature's output.

    In AD48 the Thames flooded and 10,000 people drowned. Two years later the winter was so severe that "all rivers and lakes" were frozen from November until the following April. In AD107 it rained heavily for nine months, the crops failed naturally enough and there was famine. In AD134 there was another harsh winter and the Thames froze for two months, but just five years later a drought was so severe that the Thames actually dried up for two days. AD214 the River Trent overflowed and flooded the land for twenty miles either side. In AD679 "St.Wilfred's Drought" caused widespread famine the effects of which continued to be felt for the next three years. In AD800 a great westerly gale blew that, according to contemporary accounts, "destroyed cities". In AD944 another gale blew throughout the country and destroyed 1,500 houses in London alone. In 1035 there was widespread frost on Midsummer's Day that killed the crops standing in the fields (mind you, a hundred years before in Germany, they didn't get the crops in because it was so hot that reapers dropped dead in the fields).

    England was hit by earthquakes in 1067, 1081, 1089, 1120, 1133, 1180, 1185 and 1193. However the following century it was back to floods again, in 1233, 1236 (twice), 1250, 1258, 1277 and 1287. Mind you, in 1231 it didn't rain from March until October. The 1300s were fairly quiet, but in 1407 there was frost for 25 weeks, in 1473 and 1478 the summers were so hot that farm-workers died harvesting. In 1480 there was another earthquake, and again in 1508.

    In general the 1500s were marked by severe winters, while in 1527 it rained every day from April 12th until June 3rd. 1540 and 1541 were the hottest summers for 500 years. In the early 1600s there were many severe winters - on May Day 1627 snow fell 2 feet deep all over Derbyshire, whilst in 1684 the sea froze over from Dover to Calais.

    More recently, many can remember the Great Storm of 1987, but there were similar events in 1703 when up to 15,000 sailors lost their lives, in 1713; in 1861 when up to 200 ships were wrecked off the North East coast; in 1897; in 1901 when 46 ships were lost between Berwick and the Tees with the deaths of 200 sailors; in 1908; 1943 and 1953.

    Hardly surprising, then, that the English are so obsessed with the weather. And all this took place before we'd invented Global Warming. Now of course the public and government's view at the moment is that climate change is a major worry: is this brain washing, misconception, or substantially true ?

    However there are two steps in major government revenue generation programmes:

    1) Make people fear something,

    2) Then tax it.

    This has worked for centuries !