A gnarlier ‘hockey stick,’ the same message
By Peter N. Spotts | 09.01.08
Northern-hemisphere temperatures over the past decade are likely to have been warmer than at any time in the past 1,300 years — perhaps over the past 1,700 years if tree rings have anything useful to say about it. Either time span embraces the warmest years of the so-called Medieval warm period.
That’s the latest from a team led by Penn State University’s Michael Mann, who heads the university’s Earth System Science Center. And the graph illustrating the take-home message? It still looks a lot like the much-battered, but still rink-ready stick of 1998. Today the handle reaches further back and it’s a bit more gnarly. But the blade at the business end tells the same story.
The temperature data, which actually span the globe, come from weather records dating back to 1850. To reach further back, the team relied on natural stand-ins, or proxies, that include ice cores, ocean and lake sediments, mineralized “rings” from slices of stalactites or stalagmites in caves, coral growth rings, and tree rings. Data from the southern hemisphere are too sparse to reach deep into the past with much certainty, either for the southern hemisphere or globally. The team points out that the past decade’s warming has been unusual for both, at least over the past 1,500 years. But because of the paucity of data south of the equator, they can’t rule out the possibility that for brief periods in the past, recent warming might have been topped. Overall, the researchers use the word “likely” in describing their conclusion regarding northern-hemisphere temperatures in the same way the UN-sponsored Intergovernmental Panel on Climate Change does: There’s a 66 to 90 percent chance we’re right. The work appears in this week’s edition of the Proceedings of the National Academy of Sciences.
In gathering and analyzing the data, the team says it incorporated recommendations for improving such temperature reconstructions from the National Research Council. The NRC offered up the recommendations in a report in 2006. That the NRC got involved at all highlights the challenge scientists can face when their work leaps from the pages of scientific journals few mere mortals read to become an icon for a politically controversial issue — global warming. Congress requested the report after an acrimonious hearing in 2005 over the the hockey stick and the way Mann and his team derived it. Ironically, a number of other reconstructions since 1998 have reinforced his basic conclusion, although subsequent studies and their alternate ways of looking at the data led to graphs with different wiggles and jiggles along the way.
For all the thunder and fury the original hockey stick generated (and I trust Mann and his team have their hard hats at the ready again), it’s not the hinge-pin argument for global warming. For that, researchers say, one turns to physics and the radiative properties of carbon dioxide, which Swedish chemist Svante Arrhenius painstakingly calculated — longhand — just before the turn of the 19th century. He estimated that if CO2 concentrations in the atmosphere double, global average temperatures would rise by 5 to 6 degrees Celsius. The latest estimates suggest a 2- to 4.5-degree average increase globally.
So why bother with contentious reconstructions? Gavin Schmidt, a scientist with the National Aeronautics and Space Administration’s Goddard Institute for Space Studies in New York notes several reasons, not the least of which is to serve as a reality check on climate models.
Note: Eoin O’Carroll is on vacation. He will return Sept. 2.
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2. Jeff | 09.01.08
This has to be an April Fool’s Day gag, right?
Michael Mann’s original hockey stick made him such a laughing stock in the eyes of the world, it’s hard to believe any scientific body worth its salt would keep him on the payroll. He has been thoroughly discredited, why would anyone believe a word he says?
3. Andrew | 09.02.08
The climate change deniers would claim that black is white. You cannot convince someone of something which it is in their economic interest to disbelieve.
4. Tim D | 09.02.08
Back in 2006 the US National Academy of Sciences was asked by the US Congress to find an answer to what period was the warmest of the past millennium. They looked at seven different reconstructions of the past 1100 years of climate, from 900 to 2000. Each of these studies used different methods, and each showed the same conclusion as the Mann Hockey Stick.
The people who tried to discredit it looked for anything, no matter how small, that could be tarnished so as to claim the whole thing was tarnished. Mann is respected in his field, if he’s gone back to this again I imagine he’s pretty confident about his ground this time round.
5. A. Viirlaid | 09.02.08
Can we really believe Dr. Mann after he cried WOLF! just one time too many? His (and his colleagues’) website can be found at http://www.realclimate.org/
What about the fact that in 2007 NASA adjusted its own records to show that 5 of the 10 hottest years in the U.S. mainland occurred prior to 1940? Please see http://services.alphaworks.ibm.com/manyeyes/view/SIk76IsOtha6r4mhQs1ZI2~ NASA was forced to change its own statistics by Steve McIntyre who found an anomaly in the records. Please see http://www.climateaudit.org/?p=1880
Steve McIntyre’s website is at http://www.climateaudit.org/
It is true that this change by NASA was not a WORLDWIDE revision of historical temperatures. But it is also clear that the U.S. has better temperature record-keeping than most other places. This should serve as a warning to those of us who think that the Climate Change question has been solved.
Especially because in the 1930-s we could hardly blame Carbon Dioxide for the extreme heat and Dust Bowl conditions in America. http://en.wikipedia.org/wiki/Dust_Bowl — The percentage of Carbon Dioxide in the atmosphere only THEREAFTER showed the rise caused (perhaps) by human activities. Even this is in dispute, since some climate scientists suggest that natural climate warming is what causes the oceans to release more carbon dioxide in net terms than they absorb (as temperatures rise).
Sunspots have been essentially nonexistent for the past year. They should have returned as part of the next solar cycle. This is another indicator that something is amiss. The winter of 2007-2008 may become the new norm for awhile — please see http://www.sciencealert.com.au/opinions/20082105-17356.html and also http://www.sciencealert.com.au/opinions/20082105-17355.html
If you are interested in seeing the current number of sunspots, please go to link http://www.spaceweather.com/
Sunspots have historically been a fairly good indicator of our Sun’s relative level of activity — the more sunspots, the more active. Conversely, the fewer, the lower relative level of activity — and thus a somewhat colder climate for us. Stay tuned!
Also see http://www.climateaudit.org/?p=3501
and
6. Jim Fisher | 09.02.08
I’m not a scientist and I read reportage on this topic and the reports the stories are based on, and I find the conclusions of some scientists very baffling. Repeated studies appear to show the same results, yet there is a group of people who scream at the top of their lungs that global warming is a scam. CO2 levels in ocean waters measure twice what they did ten or twenty years ago. It’s a scam. It’s a fraud. The jet streams crossing N. America have moved North by x degrees and mean temperatures go up in the American SW by 2 degrees f in ten years. It’s a scam. It’s a fraud. Tree and shrub varieties are moving North by 40 or 50 miles over a twenty year period, insect infestations that thrive in warmer temperatures than we’ve none in British Columbia over the past thousand years are killing whole forests, the ice pack at the N. Pole is the lowest in a decade, etc., and so on. It can’t all be a scam or a fraud. Something is going on. My non-scientific opinion is that global warming denyers are in the same catagory as holocast denyers. They either have some political or economic agenda, or, and this is much more likely in my humble opinion, they simply have their heads up their respective *****. Pick one. It’s up to you. I’m tired of listening to your nonsense. Our planet and our species is in serious trouble. We could be facing a massive die-off if not extinction of our race, and you’re making it worse. There have been seven mass extinctions before, and the die-off data looks remarkably what we’re experiencing today. I’m not a scientist, and I see it clearly. Not based on what others tell me. Based on what I see and read in source documents.
7. jeff id | 09.03.08
This is a joke, the tree ring data is very weak and Mann’s statistical analysis made him the joke of the science community. If you want the real story of the dead hockey stick you can learn the problems it had and how the UN IPCC did everything they could to keep it at the link below.
The tree ring data has such noisy results because not just temperature affect the data, scientists know that. This doesn’t make the data bad, but concluding that they know the temperature 2000 years ago to this degree of accuracy is FALSE and bad science.
They don’t want you to know that the temperature has actually cooled this decade. We haven’t had any warming whatsoever in the last 10 years. No scientists disputes that. The head of the IPCC which is the granddaddy of all global warming hype even says it hasn’t warmed this century.
For more information go to
http://noconsensus.wordpress.com/2008/09/02/only-99-months-until-the-end-of-the-world/
8. Ann-Drea | 09.03.08
I have to agree with previous comments that Michael Mann’s team lost all credibility. However, the new models show similar results. It is better to look a variety of models and compare them rather than trust one group’s findings.
9. Steve | 09.04.08
Wiggles and jiggles?
If the previous Hockey Stick stood up to scrutiny, why do we need a new one? Mr Stott fails to cover the criticism of the report adequately.
The bias displayed here serious ethical questions about the Monitor’s coverage of climate change issues.
10. Jeff Id | 09.04.08
The previous hockey stick was very widely discredited. For a history go here
http://noconsensus.wordpress.com/2008/08/31/the-death-and-resurrection-of-the-hockey-stick-the-jesus-paper/
11. pizza | 09.10.08
tree data are controlled by temperature, precipitation and CO2 concentration. Currently, those have been changed by human-activity (greenhouse gases and aerosol), so current instrumental data cannot be used to constructed past. Tree data obtained from instrumental data have contaminated by human-activity. I think that past reconstruction of proxy based on instrumental data is very bad and bad. If so, can we get anomalous climatic change at present?
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1. Chris Maddigan | 09.01.08
The team lead by Mann has lost all credibility. They way they have deliberately obfuscated errors in their results, refused to disclose their methods, publish their data and kept on pushing flawed analysis makes anything they publish highly suspect. That their latest publication confirms their earlier results is neither suprising or informative. It is just a continuation of their standard behaviour.
AS for the physics and Arrhenius, you misquote his results. On the basic physics Doubling CO2 would lead to a 1 degree Celsius rise in temperature. To get the inflated figures published by the IPCC you need the magic of the models.