Sounds weird, but that is indeed what it looks like. In the Global Warming (GW) debate, one of the holy scriptures is the Mann, et. al. hockey stick. The hockey stick is a recreation of temperature anomalies for the past 1,000 years for the northern Hemisphere. The shape of the reconstructed data series is like a hockey stick, mostly flat except in modern years where the series climbs steeply like a hockey stick.
Now it looks like the hockey stick result is due to flawed mathematical algorithms used to generate the data.
But now a shock: Canadian scientists Stephen McIntyre and Ross McKitrick have uncovered a fundamental mathematical flaw in the computer program that was used to produce the hockey stick. In his original publications of the stick, Mann purported to use a standard method known as principal component analysis, or PCA, to find the dominant features in a set of more than 70 different climate records.But it wasn’t so. McIntyre and McKitrick obtained part of the program that Mann used, and they found serious problems. Not only does the program not do conventional PCA, but it handles data normalization in a way that can only be described as mistaken.
Now comes the real shocker. This improper normalization procedure tends to emphasize any data that do have the hockey stick shape, and to suppress all data that do not. To demonstrate this effect, McIntyre and McKitrick created some meaningless test data that had, on average, no trends. This method of generating random data is called “Monte Carlo” analysis, after the famous casino, and it is widely used in statistical analysis to test procedures. When McIntyre and McKitrick fed these random data into the Mann procedure, out popped a hockey stick shape!
That discovery hit me like a bombshell, and I suspect it is having the same effect on many others. Suddenly the hockey stick, the poster-child of the global warming community, turns out to be an artifact of poor mathematics. How could it happen? What is going on? Let me digress into a short technical discussion of how this incredible error took place.
Without Mann et. al., the argument in favor of GW is tremendously weakened. Although, it does not scuttle the GW hypothesis, it does re-open the debate.
Posted by Steve at December 15, 2004 01:17 PMI'd want to see this reviewed a bit further. M&M got filleted on their last analysis, but it wasn't until much later.
Waiting and seeing, waiting and seeing.
Posted by: Slartibartfast on December 15, 2004 02:26 PMI haven't paid too much attention to this since I posted on it last July, when Nature forced Mann et al to publish a Corrigendum.
If you want to see the difference in graphs between the Mann data and the random number generated graph, look here where M&M will keep you up to date on all the minutia from their side of the dispute. Note the similarity of the two graphs.
This is the process of science that I admire. What's shameful is the whole Bjorn Lumberg censorship that happened at Scientific American.
Posted by: TangoMan on December 15, 2004 03:36 PMI remember something about margins of error, am I off base? My mind is awash in so much information it's hard to sort it out... ya... that's my story...
Posted by: Ron on December 15, 2004 03:54 PMSteve doesn't make it clear, but you must remember that the whole reason for Mann's faked "Hockey stick" was to support the claim that current warming is unprecedented.
Because if the current warming is not unprecedented then the deduction that it is caused by man is reduced to a poor conjecture ... like so much of the global warming hypothesis. Especially when mixed with increasing evidence of the sun's variability.
Posted by: Robin Roberts on December 15, 2004 05:13 PMPeople happily find stock market cycles even today. I think it was in the 50s that somebody observed that you're finding the transfer function of your filter.
The reason to doubt global warming as it's put forth isn't such mathematical mistakes or misconceptions, but that they're doing cut-and-paste pastimes, not science. It's science only in its props, like in a movie.
It's fashionable because it attracts government funding, which in turn depends on its scare-women story potential, for the target news audience. Science writers write about it because people will buy the article. Self-delusion only makes it better.
By 2050, the earth's population will be entirely women entirely watching TV news. You get this result by linear extrapolation.
The Hardin test for science is whether the field can be made interesting. At some basic level it has to be something you can think about yourself.
It's not a closed mind so much as a busy one; and I've seen this before.
Posted by: Ron Hardin on December 16, 2004 03:43 AMPeople need to watch out doing Monte Carlo using Excel. Excel does not have a "robust" random number generator. It starts repeating after a few thousand numbers (that's what that whole "seed" option is all about).
So...
Has anybody checked the checkers? How much faith do we have that the MCA was done correctly?
Posted by: Buzzcut on December 16, 2004 11:28 AMI don't get this.
Why all the people on the right wing wants to "prove" that global warming is false?
Why whenever I see a critique to that claim is almost always coming from free market oriented people?
I see as many attacks on the welfare state as I see on GW.
Why?
Fernando
Posted by: Fernando on December 19, 2004 02:31 PMBecause you can't read very well. Yes I'm afraid that is the answer. You see, this post doesn't "prove Global Warming" is false. Hell I even note that. Also, if you look at the GW posts here you'll see I don't dispute it so much as dispute
1. The magnitude.
2. That the right answer is to cut back on green house gases.
My point is that there is a large correlation between being a free market advocate and denying or minimizing GW (or at least that GW is man made).
I see a strong ideological factor.
I see a strong correlation between being a free market advocate and denying or minimizing the impact in the world economy of the peak oil production, too.
I supose that you're pretty sure that markets will eventually "adjust" the situation allowing a smooth transition to a non oil-based economy, preserving in the process the standard of living of the first world (let's forget about the thirld world).
But why is it so? Why is this correlation so high?
Do you see ambientalist movement as "a new left"?.
Do you think that we can't predict the future (or at least a probable one)?
Do you dismise any malthusian like argument because free markets can solve this kind of problems (a hayekian view)?
Fernando
Posted by: Fernando on December 19, 2004 07:47 PMAmbientalist? does the word belong to the english language? "Evironmental movement" I should have said.
And what about this article in a peer-reviewed magazine?
http://www.sciencemag.org/cgi/content/full/306/5702/1686
Posted by: Fernando on December 19, 2004 08:00 PMFernando:
To begin with, not every article in Science magazine is peer-reviewed. Indeed, the article you cite is not "peer-reviewed."
Second, whether or not there is a "consensus" is a matter of opinion. IIRC, there was a "consensus" at the time that "nuclear winter" was a reality. Carl Sagan said so! Yet, further studies (including better model-building) eventually concluded that much of it was nonsense.
As to global warming and free market issues, you need to break the problem up into pieces (as has been done elsewhere in this very blog).
At its heart, though, it comes to the following:
1. Is there global warming? Yes.
2. Are humans the cause of that global warming? Unknown, with significant reason to doubt that humans are the cause or even primary cause.
3. Can human actions be undertaken that would influence global warming? Unknown, w/ much of the answer, of course, depending on your response to "2."
4. Is Kyoto the right actions to be undertaken? Well, that obviously depends on "2" and "3" above, but it also requires taking into account the likely costs of Kyoto, which too many of its defenders fail to have done, and set them against the likely benefits of Kyoto (which relies, in part, on how you view "2" and "3").
The folks who believe in Kyoto may or may not, in fact, believe in global warming---I would suspect that many anti-globo types latch onto Kyoto w/ little regard of the accuracy of the science behind it. Indeed, one might ask you: Is there an ideological component to supporting Kyoto? Is there a reason so many anti-globo types support it as well?
Posted by: Dean on December 20, 2004 07:36 AMIt's true. I should have said "an article on the level of consensus among scientist and how it was determined using peer-reviewed publications", instead.
I quote
"The drafting of such reports and statements involves many opportunities for comment, criticism, and revision, and it is not likely that they would diverge greatly from the opinions of the societies' members. Nevertheless, they might downplay legitimate dissenting opinions. That hypothesis was tested by analyzing 928 abstracts, published in refereed scientific journals between 1993 and 2003, and listed in the ISI database with the keywords "climate change" (9).
The 928 papers were divided into six categories: explicit endorsement of the consensus position, evaluation of impacts, mitigation proposals, methods, paleoclimate analysis, and rejection of the consensus position. Of all the papers, 75% fell into the first three categories, either explicitly or implicitly accepting the consensus view; 25% dealt with methods or paleoclimate, taking no position on current anthropogenic climate change. Remarkably, none of the papers disagreed with the consensus position.
Admittedly, authors evaluating impacts, developing methods, or studying paleoclimatic change might believe that current climate change is natural. However, none of these papers argued that point.
This analysis shows that scientists publishing in the peer-reviewed literature agree with IPCC, the National Academy of Sciences, and the public statements of their professional societies. Politicians, economists, journalists, and others may have the impression of confusion, disagreement, or discord among climate scientists, but that impression is incorrect.
The scientific consensus might, of course, be wrong. If the history of science teaches anything, it is humility, and no one can be faulted for failing to act on what is not known. But our grandchildren will surely blame us if they find that we understood the reality of anthropogenic climate change and failed to do anything about it.
Many details about climate interactions are not well understood, and there are ample grounds for continued research to provide a better basis for understanding climate dynamics. The question of what to do about climate change is also still open. But there is a scientific consensus on the reality of anthropogenic climate change. Climate scientists have repeatedly tried to make this clear. It is time for the rest of us to listen."
Regarding Kyoto there are ideological component on both sides, but I'm not talking about that, what I'm saying is that whenever I see an opinion "minimizing" GW issues there is a free market or right wing supporter.
Science is saying that GW "is true" and "man made" as far science knows by now .
Obviously, you can always disagree with Science, but what I see here is a more deep trend regarding simple and pure ideology.
It is very rare to read in any "free market" oriented blog, some sort of agreement with the consensus of the sciencists, instead what I see is a strong desire to prove them wrong.
Fernando,
Why is there such a strong correlation between big government/statist types and those who believe in catastrophic global warming?
You know...that pot, kettle, black thing.
As for consensus science, there was once consensus that atoms did not exist. So much for that.
Posted by: Steve on December 22, 2004 11:52 AMWell, Science is backing up that assertion, not only statist/big goverment types. And Science in the end, IS consensus.
What you are describing is the method of science, no big news.
But in your same vein we are allowed to believe in aliens from outer space and flying pyramids and the like because consensus science once believed that atoms didn't exist.
And I don't hope to see you backing up one of those claims.
Go, disprove whatever Science says because as I've said Science in the end is consensus. That's the way Science evolves. And you know that, of course.
So, you prefer your ideology over Science based on the idea that consensus is nothing.
Sorry, I'm not convinced.
Posted by: Fernando on December 22, 2004 08:45 PM