Several comments in the general discussion have related to the global warming question. We’re going to move them here so that the topic is easier to find. This turned out to be one most controversial topics on the ASA email list during November and December of 2009. We recognize that there is a diversity of views in the ASA on this issue. We also recognize that as part of creation care or stewardship of the environment that is an important faith/science issue. We hope that the discussion here will not turn into rancorous partisan politics or to simplistic arguments between so-called global warming “believers” vs. global warming “skeptics”.
Burgy (and others who rely on IPCC’s probability estimates) IMO the equation IPCC makes: 95% – highly confident, 67% = confident amounts to circular reasoning. To see how to make a start doing realistic probability estimates, read a book like “Quick analysis for busy decision makers” by Robert Behn and James Vaupel, New York, Basic Books 1982. Without a discipined analysis such as Vaupel and Behn’s, probability estimates are wishful thinking. Has IPCC done the analysis? Maybe — buried somewhere in their reports, but I wish people who cite IPCC for probability estimates would also give a reference to their methodology. I’ve done a little hunting through their reports and haven’t found anything.
The IPCC reports uncertainty in three ways:
1. How certain is the assertion.
2. The level of understanding
3. The actual error bar spread.
In the case of the value of the climate sensitivity with respect to CO2 we are highly confident of the assertion and the physics is well understood but the error bars have been frustratingly sticky over the decades. That is the most likely value gets validated and re-validated over and over and over again but the three sigma spread has been invariant and large. Still, Richard Lindzen remains outside the three sigma values! The net result of this is the climate simulations can have a fairly large spread.
A different situation exists for aerosols. Because the chemistry for these is much more complicated than CO2 and because there are many of them it’s not as well understood. Jim Hansen begged unsuccessfully for satellites to measure this during the 90s but we are still not where we should be on the earth science budget for NASA.
Even worse is the situation where we are at the very leading edge in the science which means there is a lot of uncertainty and these are in the areas everybody cares about, e.g. ice melt and sea level rise.
There are three working groups in the IPCC. WG1 and WG2 seem to have different approaches to poorly understood science. WG1 completely dropped the effect of ice melt on sea level because it was not accurately being predicted. WG2 used the so-called “gray literature” to make what we now know is a bogus prediction of glacier melt. Gray literature is groups like the WWF and science new magazines that produce non-peer reviewed literature.
Since then we’ve had peer reviewed and better understood science so that we don’t either throw up our hands or cite unreliable sources. The IPCC is becoming increasingly irrelevant due to the speed of both the climate change and our scientific understanding. We need a process that reviews the literature that is more nimble. President Bush charged the NAS to look at global warming but dismissed their report because they disagreed with one person, Richard Lindzen. Given the change in administration it is probably a good time to have a repeat review for this decade. A lot has happened since 2007.
Thanks for your comment, Burgy. Could you tell us more specifically about what you read in Schneider that encouraged you to revise your confidence level? Hubris is certainly present in advocates, as well as on all sides. It’s a bit hard to quantify and fold into the data.
I agree that the IPCC “per cent confidence level” never impressed me very much. Rich’s comment below helps a little bit but this kind of confidence level seems very different from the standard statistical analysis type.
One more point about consensus science that I may not have clarified in my post on that topic. Consensus science is determined by the spectrum of ideas published in the peer-reviewed literature by researchers active in the field. Once those ideas have coalesced into general agreement with disagreement at the detail level rather than the big picture, one can say that consensus has been attained. It’s not always easy to determine when that is the case. It really can best be determined by those active in and very familiar with all the latest literature on that topic. It certainly does not mean that agreement has been reached outside the set of researchers in that field. That seems to be the case in AGW. As far as I can tell, consensus seems to have been reached within the set of AGW researchers but not in the set of scientists in other fields with some degree of interest in and knowledge about climate. In contrast to the situation 20 years ago, blogs and other media make it much easier to have a discussion of those differences of opinion. I think that can be extremely valuable and should be encouraged–as long as it can be done with a high degree of civility and respect for each other.
Randy
By necessity that measure is subjective. It also can get political. For example, the point in the Summary for Policy Makers about whether AGW was real was made less certain at the insistence of China and Saudi Arabia. (All statements in the SPM have to be passed line by line unanimously.) Still, if you go to the detailed report it’s pretty easy to see why there is the scoring that’s there.
Statements with a high certainty have a large number of studies that come to the same conclusion and even more so have studies that address the issue at hand via different techniques. Thus, it’s possible to check the work and not take the values on faith. In fact, that was how the recent bad glacier prediction was caught when it was noted that they only cited gray literature. There was no robust repeatability at all.
One of the techniques that is supposed to help with mitigating global warming is reforestation. Note this disturbing report where rain forest reforestation is not going as well as planned.
Here’s a report from today’s Salt Lake Tribune:
Utah House passes resolution doubting climate science (02/10/2010)
The Utah House of Representatives adopted yesterday a nonbinding statement expressing deep doubts about climate change science and urging the federal government to desist from efforts to regulate carbon dioxide emissions. The resolution was passed by a 56-17 vote after the removal of references to a “climate data conspiracy” and climate change “gravy train” that were included in the original statement.Rep. Kerry Gibson (R), the sponsor of the resolution, said he believes humans have little influence over climate change and government regulation would impose staggering costs.’I’m afraid of what could happen to our economy, to our rural life, to our agriculture, if such a detrimental policy continues to be pursued for political reasons,’ Gibson said.
NASA Finds Warmer Ocean Speeding Greenland Glacier Melt
Recent Research on Ocean Acidification
Our oceans mitigate the effects of AGW by absorbing the CO2 and storing the excess heat. This is the main reason why the Southern Hemisphere heats both more slowly and more smoothly than the Northern Hemisphere because the Southern Hemisphere has more oceans.
This effect comes with a cost. When absorbing the CO2 the oceans become more acidic. A paper in today’s Nature Geoscience compares the acidification now and 55 million years ago during the Paleocene-Eocene Thermal Maximum (PETM). The shocking conclusion is we are currently acidifying at a rate of ten times of the PETM with its concomitant mass extinction. This mass extinction is no ordinary one since it effects deep sea marine organisms which are less able to respond to the change that surface plankton might.
One of the authors of the paper put it this way to The Independent:
The following paper allows you to visualize the current acidification of around −0.0017 pH/yr. All this shows that mere adaptation to AGW is not sufficient and CO2 mitigation is still necessary to avoid severe environmental damage.
Today at the AAAS meeting I had a chance to attend part of the symposium on sea-ice modeling. This work may have been where the above quote came from. It was interesting to hear the details of the analysis of Arctic ice. It makes sense that atmospheric winds do not account for the bulk of the melting. It has to do with warm ocean currents coming through the Nordic Sea and the Bering Strait. Much of that heat is lost to other sources before it gets to the ice but there’s enough to influence the volume of ice.
Most of all, I noted the satellite data which are now able to determine the volume of ice rather than the area. The volume is far more relevant and the models fit that data better as well. Indications are that while the 2008 areal extent of ice coverage was the 2nd lowest, the volume of ice may be the record low.
Randy
Generally I agree with what you say about consensus science. Unfortunately it waves a red flag in front of nonscientists. My concern about ASA is that in trying to avoid politics, you put yourselves in danger of adopting some position — say pro-AGW as “received doctrine” and then labeling anything else as “politics”. I don’t have time to dig up much information on AGW these days. I have been diagnosed with multiple myeloma, and most of my energy goes to navigating treatment an paying for it, etc. But let in some dissent!