Archive for May, 2010

Timescales, Special Cases, Limitations, Etc.

May 26, 2010

Subtitle: Some Physical Thoughts on the notion of “Climate Sensitivity”.

It is generally agreed that the central issue in the climate debate is the magnitude of warming one would expect to occur as a result of a doubling of CO2, which results in a “forcing” of ~3.7 watts per meter squared. However, in a moment of sudden insight, I realized that, from a physics perspective, there are several problems with the way this is talked about. But let’s start with a definition. The “equilibrium climate sensitivity”-what most people in this debate think they want to know-is equal to the eventual change in temperature of the Earth that would occur per unit change in the radiative “forcing” of the system. Think about that for a few seconds.

If you have any knowledge of physics, you have probably already realized  how this notion can get you into serious trouble. Consider the following case: We shut off the sun. The Earth will begin to cool, and it will do so for a very long time, until it reaches ~0 degrees Kelvin, or a cooling  of ~288.15 K. Again, this is eventually, not on a timescale which is really relevant to policy, say. But never mind that. Incoming solar radiation in this circumstance has been reduced ~342 w/m^2. Thus the “equilibrium climate sensitivity” MUST be ~0.84 K/wm^-2, or a little over three degrees for a doubling of CO2. That is, of course, assuming that the figures I’m using for incoming solar radiation and mean surface temperature are correct. Of course, this does not correspond to the sensitivity to a doubling CO2 necessarily. For one thing, the physics governing the feedback mechanisms will be very different at temperatures that low, since the atmospheric gases would have long since ceased to be gases. However, I can only think of things which might plausibly mean that the sensitivity thus derived is too high, not too low. So one might say that very large negative forcing is a “special case” because the response is sure to be very different when the greenhouse effect can’t apply because water vapor will have frozen out, along with CO2 and everything else.

Timescale is also a serious issue. If it continues to warm indefinitely, never reaching “equilibrium” after doubling CO2, just very slowly, well, who cares if in a billion years the warming would reach 5 degrees if in the next thousand it was only 2? I know I wouldn’t. And yet it is technically the long, irrelevant period which is the “equilibrium” sensitivity. Indeed, it stands to reason that the Earth never gets to realize true equilibrium response to external perturbation, if it operates on timescales that long, the forcing is constantly changing on timescales far too short to fully realize the response.

Now I don’t mean to say that the whole concept is bunk, but there seem to be details which people overlook about this.

The Heartland Conference-Interesting Presentations Already Available

May 18, 2010

The 4th International Conference on Climate Change, hosted by the Heartland Institute is currently ongoing. A number of powerpoints from various presenters are already available, as are some videos. Naturally, I would like to makes some recommendations of the presentations already available. Lindzen had a very interesting presentation about the science, and, largely the sociology of science. I would only note that I am unsure that what he describes as the prosecutor’s fallacy is really that. In fact, I think it is more accurately described as the more fundamental fallacy of Affirming the consequent. Indeed, I would argue that all arguments for dangerous anthropogenic warming stem from logical fallacies whose structure is essentially the same as AtC-and, like all formal fallacies, is essentially a “special case” of the more general erroneous logic of a non sequitor-a conclusion which does not necessarily follow from the premises. Moving on, Harrison Schmitt went over an interesting topic I didn’t expect him to, namely the Constitution and the relevance of it’s limits on the power of the federal government to current climate legislation/regulation proposals. He makes the sure to be controversial statement that the current proposals all over step the limits of the government’s power. For what it’s worth, I think his interpretation is sound. Pat Michaels discussed how science is presently indicated that projections of large future warming are likely erroneous, and the key statement of the EPA about most recent warming being due to greenhouse gases is not supported with the high probability that they say it is. I would also like to talk a little more later about one of his more provocative suggestions-that a peer reviewed journal be started for the purpose of doing an end run around the deliberate attempts to gate-keep the literature (which we’ve talked about before). Chip Knappenberger discussed some work he has been doing to examine whether recent temperature trends are in line with future warming projections, and suggests that the observations are indicating trends which are unlikely if the models are correct. It’s very interesting but I just want to say that some the graphs he shows are very difficult to read due to having WAY too many lines on them-in particular those which look at the distributions of trends for different lengths of time. It might be better to use simpler graphs and quote p-values. Ross McKitrick discussed why he thinks that predictions of climate are currently dependent on unreasonable projections of future emissions, and his continuing work on getting a comment on the Santer et everyone one on the “team” paper claiming that the atmospheric temperature trends in the tropics are consistent with models. I also highly recommend the presentation of David Tuerk, where he comments on how subsidies, both for “green” energy and “dirty” energy are distorting the market, and how environmental advocates and free market supporters should be able to agree on eliminating perverse incentives for “dirty” energy. I completely agree. Which is nice because I was beginning to think I was the only person in the world who wanted to eliminate market distortions in energy. Gabriel Calzada Alvarez does a great job of looking at what “green jobs” programs have meant in the real world-namely much more bad than good. Roy Spencer, who’s power point is not yet available, but video is, discussed his effort to study feedbacks, and the results so far of using the Advanced Microwave Sounding Unit data to monitor surface temperature changes as a “check” on the official data like HadCRUT, and examine possible urbanization effects. There are many more presentations not up yet or even still coming up, and I don’t want to leave anyone with the impression that these are the only ones worth reading/watching-far from it, indeed there is great value in listening to all of them, even the ones I don’t necessarily agree with 😉 so you should look at any that get your interest. I am looking forward to Willis Eschenbach’s presentation, for instance, but it is not available yet. I also look forward to David Douglass’ talk. Hopefully this time the powerpoint that eventually appears will match his talk, so this time I don’t have to wait for a reply email that never comes.

Anyway, I’ll stay appraised of the presentations as they become available and will elaborate on them later.

Drop Dead ‘Cause It’s HOT!

May 13, 2010

I probably should have noted this earlier but it’s such nonsense I thought, why bother? So anyway, get this, in the future, global warming will make it so hot, people will just DIE!

Steven C. Sherwood and Matthew Huber,2010: An adaptability limit to climate change due to heat stress http://www.pnas.org/cgi/doi/10.1073/pnas.0913352107

I am not kidding. There are parts of the world that will apparently experience uninhabitable temperature conditions, hot and humid to the point that people will die just from the heat. “Despite the uncertainty in future climate-change impacts, it is often assumed that humans would be able to adapt to any possible warming. Here we argue that heat stress imposes a robust upper limit to such adaptation.” Yes. It will get so hot that wet-bulb temperatures will regularly reach ~35 degrees Celsius almost everywhere that people live, and apparently it is impossible to live with such heat. You can’t adapt to it, apparently. Considering the fact that this would, according to them, require global warming in excess of seven degrees Celsius, quite a high number by almost anyone’s standards, it doesn’t seem to be all that important to be concerned about it. But let’s be serious here for a second. Human beings are very resilient creatures, and we live, even thrive, in nearly ever climate on Earth. Sometimes it does get too hot for people, and sometimes those people don’t know to seek shelter in the air conditioning indoors, true enough. But does anyone really believe there is a temperature that the outdoors can reach that it becomes impossible for us to adapt? Really? I must be crazy, because I known that almost no one dies of heat stress in wealth, warm climates-Tampa has essentially no heat related mortality. And I know that even as the cities of the US have gotten warmer, heat related mortality has fallen. Does anyone really buy that people are going to start dropping like flies, stupid, sizzling flies, if it gets hotter? Puh-leeze!

I also recommend the technical comments of Roger Pielke Senior.