Tuesday, December 22, 2009

Polar Bears, Data, Opinions, and Global Warming

So I had a nice discussion with a student, who was confused after receiving some opposing viewpoints on Global Warming from different professors in a relatively short time period. In one of the statements, I had claimed that there were more polar bears now than there were 20-30 years ago. In another statement, another professor claimed that the polar bears were dying off due to arctic ice retreat due to global warming. This is actually a nice case of "follow the data", where the problem is defined in a relatively concrete way. Another example of this is the question "is it warmer now than 1000 years ago?". On the second question, www.realclimate.org would say "yes, it is warmer than 1000 years ago" and cite the proxy data, etc... www.climateaudit.org would say (I believe) "maybe, maybe not" and cite the issues with the analysis of the proxy data.

Now, back to the polar bears. From the polarbearsinternational it is confirmed that the population of polar bears from the 1960's was very low, in the few thousands, and in the early 2000s was up to between 22000-25000. These are also reflected in the usgs site on polar bears where you can actually get some of the data.

If you go to the polar bear specialist group which advises for the IPCC, you can find a table of the status of the polar bear in various regions. The problem with this table is that there is a column titled "Observed or predicted trend". Hello? Why would you mix observed trends and predicted trends in a table? Just show me the data. Anyway, there is a document here which has an explanation of the projections, and possibly some data, although I haven't read the 200 pages of the document to see if it is buried in the text (there is no figure with the data...just model predictions). I'd love to find a straightforward presentation of the estimates of the current numbers of polar bears, complete with error-bars to denote uncertainty.

It seems reasonable that with the decline of the arctic ice that the polar bear populations can be affected, some more than others, but the role of hunting (the regulation of which caused the surge in the bear numbers from the 1970s) still plays a role can is difficult to disentangle...I've seen unsubstantiated claims that the areas with the decrease are primarily hunting areas. I haven't confirmed this, but this could also be the fact that ice retreat will be more substantial in the more habitable areas, where there would be more people. Correlation does not equal cause and effect.

So, it is a fact that there are many more polar bears now than, say 30-40 years ago. It can also be true, although I have difficulty tracking the data down in a readable form, that arctic ice retreat could impact polar bear numbers adversely.

One question that I have now is, if it was warmer 1000 years ago, is there evidence that there was a significant retreat of the ice back then? If that is the case, then the polar bear scare is just that...a scare. Again, many of global warming consequences that are being reported are tied to the question of the size, extent, and effects of the Medieval Warming Period. That's why, in my opinion, that is the most important question of all.

Tuesday, December 15, 2009

Open Information, Reproducible Research, and Climategate

David Donoho, the creator of Wavelab is featured in an article about reproducible research in the journal CISE (Computing in Science and Engineering). I am struck by the resonance of a couple quotes, as they apply to Climategate and Climate Modeling:

The scientific method's central motivation is the ubiquity of error--the awareness that mistakes and self-delusion can creep in absolutely anywhere and that the scientist's effort is primarily expended in recognizing and rooting out error.


In stark contrast to the sciences relying on deduction and empiricism, computational science is far less visibly concerned with the ubiquity of error. At conferences and in publications, it's now completely acceptable for a researcher to simply say "here is what I did, and here are my results." Presenters devote almost no time to explaining why the audience should believe that they found and corrected errors in their computations. The presenter's core isn't about the struggle to root out error--as it would be in mature fields--but is instead a sales pitch...


Many users of scientific computing aren't even trying to follow a systematic, rigorous discipline that would in principle allow others to verify the claims they make. How dare we imagine that computational science, as routinely practiced, is reliable!

On ClimateAudit, there is an older article (2005) about the Hockey Stick plot. Ross McKitrick makes the suggestion of an audit panel,

A group of experts fully independent of the IPCC should
be assembled immediately after the release of any future IPCC Reports to
prepare an audit report which will be released under the imprimatur of the IPCC itself. The audit will
identify the key studies on which the Report’s conclusions have been
based, and scrutinize those studies, with a view to verifying that, at a

  • data are publicly available,
  • The statistical methods were fully described, correctly
    implemented and the computer code is published
  • If the findings given maximum prominence are
    at odds with other published evidence, good reason is provided in the
    text as to why these findings have been given prominence.

Any competent scientist can assess these things. My strong
recommendation is that such a panel be
drawn from the ranks of competent mathematicians, statisticians,
physicists and computer scientists
outside the climatology profession, to prevent the conflict of
interest that arises because
climatologists face career repercussions from
publicly criticizing the IPCC. Also, participation should
exclude officials from environment ministries,
because of the conflict of interest entailed in the fact
that environment ministries are the main financial
beneficiaries of the promotion of global warming fears.

The second recommendation is for a "counter-weight panel", whose job would be to actively try to find holes in the analysis, assumptions, etc...

I'm not sure how I feel about the second one (I'll have to think about it), but the audit panel to me makes total sense. Why don't the scientific journals do this as a matter of policy?

Saturday, December 12, 2009

Word of the Day: Micromort

I'm not starting a new "word of the day" series, but I did learn this work today from the following video on risk analysis:

It's an entertaining introduction to risk analysis, and they use the word micromort, referring to a measurement of the quantity of an action which gives you a 1 in a million chance of dying. The website is www.understandinguncertainty.org.

Thursday, December 10, 2009

Climate Change Denial is not the same as Evolution Denial

Articles like this one and this one and others make the comparison between, what they call, global warming deniers and evolution deniers (aka Intelligent Design (ID) proponents), and even holocaust deniers. Personally, I find these comparisons misleading and dangerous. It is true that there are some who believe that climate is not changing at all, and that flies in the face of all of our knowledge of climate, weather, and the Earth system. Then there are those, like in climateaudit.org, that criticize the statistics of the data, and the possible false conclusions that can arise from that, and the lack of transparency on such an important topic. Lumping them in with the ID crowd is just ridiculous.

Why is the scientific consensus on Anthropomorphic Global Warming (AGW) different than the scientific consensus on Evolution? Let me list some of the ways:

  1. Evolution has many independent, very different, lines of evidence (fossils, embryology, immunology, molecular biology, paleontology, etc...). AGW has at best 50-100 different data sets, from the dozen or so tree rings, to the dozen or so ice cores, satellite and surface temperature records. Much of our inference comes from computer simulations, that a very few completely understand. Much of global warming consensus comes from a small minority that are directly involved with the data or the simulations.
  2. We can control aspects of evolution. With knowledge of DNA, we can make genetically modified foods, we can change the course of diseases, and breed bacteria to eat nylon. Our understanding of AGW is at such a low level that we can only possibly control the climate at the grossest level. Our lack of understanding of feedback loops prevents even the most basic possible control of the system.
  3. Although evolution occurs on long time scales, we can see its action on the small scale. AGW also occurs on longish time scales, but there is no short-term equivalent. This adds to our level of control (with evolution), or lack of it with AGW.
  4. Those that are denying evolution want to replace it with something that violates not just evolution, but all of physics, chemistry, astronomy...pretty much all of science. Although the extremists in the anti-global warming camp can seem pretty anti-science, they aren't trying to replace global warming with something that violates all of science (they still might be wrong!). There is also a much more nuanced camp that admits that the planet is warmer, but perhaps it is not as special as the AGW theory would suggest, and that draconian CO2 policies are unwarranted given the uncertainties. This puts it on a very different scale than the anti-evolution group.

It is dangerous to make the comparison. One is partly the demonizing of your opponent and, at the same time, angelizing (is that a word? :) ) ones own perspective: by saying that the AGW deniers are just like the evolution deniers, both makes the deniers seem unreasonable, but by association, implies that AGW is as solid as evolution. This latter claim, despite the claims of its proponents, is definitely hyperbole.

Wednesday, December 9, 2009

Climategate, oh my!

I've been reading a lot about Climategate, and have a few comments now, and hopefully more to come. What sparked this current thread of thinking for me was this post over in the Statistical Modeling blog. He summarized the physicists perspective on the "settled science" in a nice way:

The evidence for anthropogenic (that is, human-caused) global warming is strong, comes from many sources, and has been subject to much scientific scrutiny. Plenty of data are freely available. The basic principles can be understood by just about anyone, and first- and second-order calculations can be perfomed by any physics grad student. Given these facts, questioning the occurrence of anthropogenic global warming seems crazy. (Predicting the details is much, much more complicated). And yet, I have seen discussions, articles, and blog posts from smart, educated people who seem to think that anthropogenic climate change is somehow called into question by the facts that (1) some scientists really, deeply believe that global warming skeptics are wrong in their analyses and should be shut out of the scientific discussion of global warming, and (2) one scientist may have fiddled with some of the numbers in making one of his plots. This is enough to make you skeptical of the whole scientific basis of global warming? Really?

I would love to go point by point in this quote and show the calculations, and I'd imagine that it would get stymied once I tried to put in the water vapor feedback. I need to read more about this, because from what I've read we don't understand the magnitude, or sign, of the cloud feedback and that it could easily wipe out any warming caused by CO2 increases.

Some of the comments are very good too, like:

A. zarkov: I'm really disappointed to see you engage in the usual group think about global warming. Have you read the Wegman report? How come you don't refer people to ClimateAudit for the other side of the debate? Did you know that Michael Mann had to be forced by Congress to provide the data and codes behind the hockey stick calculation? ClimateAudit give you everything, the data and the R code they use. The other side stonewalls, and no wonder-- their results are a fraud.

The blog he refers to, climateaudit.org, is very interesting and is exactly the way the commenter says: they are all for open information. They post the data, the code, everything right up front and simply ask everyone else to do the same. Why this isn't required for all scientific publications, I don't know. Why it is not required for all high-stakes publications (ones that could result in very high-stakes policy) I don't know either. It's a travesty.

If everyone were as open about the data and the code, Climategate couldn't have happened.

One final comment on this thread:

Radford, Neal: Few people ever disputed that the current temperatures are higher than those of earlier times back to four hundred years ago. The big issue has always been whether the Medieval Warm Period (usually seen as occuring around a thousand years ago) was warmer than at present, since if it was, that makes the present warming seem not so unusal and perhaps due to natural causes.

This is my point too: if it was warmer 1000 years ago, then the hysterical language of the global warming media is completely unjustified.

From RealClimate.org:
Phil Jones in discussing the presentation of temperature reconstructions stated that “I’ve just completed Mike’s Nature trick of adding in the real temps to each series for the last 20 years (ie from 1981 onwards) and from 1961 for Keith’s to hide the decline.” The paper in question is the Mann, Bradley and Hughes (1998) Nature paper on the original multiproxy temperature reconstruction, and the ‘trick’ is just to plot the instrumental records along with reconstruction so that the context of the recent warming is clear. Scientists often use the term “trick” to refer to a “a good way to deal with a problem”, rather than something that is “secret”, and so there is nothing problematic in this at all. As for the ‘decline’, it is well known that Keith Briffa’s maximum latewood tree ring density proxy diverges from the temperature records after 1960 (this is more commonly known as the “divergence problem”–see e.g. the recent discussion in this paper) and has been discussed in the literature since Briffa et al in Nature in 1998 (Nature, 391, 678-682). Those authors have always recommend not using the post 1960 part of their reconstruction, and so while ‘hiding’ is probably a poor choice of words (since it is ‘hidden’ in plain sight), not using the data in the plot is completely appropriate, as is further research to understand why this happens.

A must read is the article by David Holland,
which outlines the problems with the hockey-stick analysis. He explains the divergence problem, and the
history of all this far better than I can summarize here.

Sunday, December 6, 2009

Universality of Religion

On the Effect Measure blog, there is post about "Freethinker Sunday Sermonette: Dawkins on evolution and religion", with the following video:

I am struck by a few things.

  1. First, in the blog post he mentions:
    It assumes that all things we call religion or religious impulses are essentially the same or have some common core. This faces the philosophical problem of properties and propositions in general. For example, take the property of redness. Is there something that all objects we call red have in common? And if there is, is this the same kind of thing we call religious belief?

    In fact there is something common to all things red: the wavelengths of light that are absorbed. I think what he is asking is whether we experience red in the same way as our friend. In fact, it is quite likely, and it is not a philosophical idea at all. It seems to me more and more that philosophy tries to handle questions that are out of reach for science (for the moment) but the solutions found in philosophy evaporate or are insubstantial once we really understand what is going on. Tom Mitchell has done some very interesting work with looking at fMRI data in his "Brains, Meaning, and Corpus Statistics" talk (talk slides on his home page).

    In the work, he compares fMRI data from different individuals, and finds that he can correctly identify images and words from brain activity of one person, using the associations between the images and words derived from the brain activity of other people. This strongly suggests that the internal representations of words and concepts may be very similar between individuals. Not only that, but that we have the possibility of determining what those are and not just leave it up to philosophical ruminations.

  2. Dawkins mentions belief in authorities as a psychological tendency that may lead to religious thinking under the right circumstances. I would further add the brain's tendency for seeing patterns where there are none as the other piece of the religious-thinking puzzle. It is evolutionary advantageous to see tigers where there are none as opposed to not seeing tigers where there are some. Not all errors are equally costly. Religious interpretation of experience seems to me to easily follow from these sorts of errors.