Guest Rant of the Week: Climate Change

My coworker, an anthropogenic climate change denier, forwarded me this article about a climate change scientist:

No smoking hot spot

This guy contends, “by 2007 the evidence was pretty conclusive that carbon played only a minor role and was not the main cause of the recent global warming.” Since I’m not exactly knowledgeable in climatology, I asked for by best friend Micah’s reaction. (Micah’s one month away from a PhD in physics from UW). Here’s his response:


My position is that WE DON'T KNOW about the feedback mechanisms that control global temperature.

Cartoon picture: keep track of all the energy coming in and going out. In the (quasi-)steady state, these must be equal. Obviously solar radiation and geothermal energy heat the earth surface; energy is lost by reflection or re-radiation. The loss mechanisms become more effective at higher temps (the heating mechanisms do not depend on temp), and the avg. temperature is the one at which the incoming power is balanced by outgoing power.

The problem is the loss mechanisms are very complicated (the incoming solar flux is pretty easy to deal with). The global climate system is too complex to simulate (ever wonder why your cat is about as good at predicting the weather as the TV weatherman?). So we don't know what is going to happen, but CO_2 levels are higher now than they have been for a very long time, and headed up. Our choice now is to choose whether or not to run the experiment that will show us what happens when you increase CO_2. If we want to see, we can just keep flying, burning coal for electricity, and running our F350s and reading 'Auto Trader' in the store parking lot while our wives are inside chatting up the cashier.

I would not believe any predictions regarding temperature from anybody regardless of their political tendencies, b/c the science is not there. In science you have to be skeptical. To my mind, the pressing problem is not temperature but atmospheric composition, which is not controversial. Neither is the source. It has been widely believed for a long time that increased CO_2 means greater temps via the greenhouse mechanism (the surface cools more slowly b/c long- wavelength radiation is less likely to escape the atmosphere). I assume the 'hot spot' he is talking about is due to the deposition of this radiation in the CO_2-rich atmosphere (at 'normal' CO_2 levels the energy escapes. But it is a complicated system with many factors (e.g. cloud formation, ocean currents, polar ice, etc.). I'm not sure how well the greenhouse effect is understood in real systems (e.g. I don't think we could accurately predict the surface temp. of Venus from knowledge of its orbit and atmospheric content -- but we could say with confidence that it is higher than it would be w/o such a dense atmosphere).

In the same vein I do not believe that failure to observe the 'hot spot’ is definitive evidence that the greenhouse effect is not raising temps. It could be there and unobserved (experiments are really hard -- it took forever to observe the neutrino, with many failed attempts, but, holy shit, it turned out to be real!!). Or the greenhouse mechanism could be working but not exactly as expected. OTOH, if an anomaly was predicted and then observed, I would take that as strong evidence that the theory making the prediction had some validity. I think the public has difficulty dealing with uncertainty in science. Which is too bad, b/c that's mostly what you get.

Oh yeah, and by the public, I mean Al Gore. I thought it was immoral (almost evil) and almost certainly unproductive to insinuate a link between large storms and CO_2 emissions in his movie. It's not that I don’t think such a link is likely (seems very plausible to me), but there is no data yet. When Gore promises that we can avoid trouble by cutting emissions, he is making an assertion that he can not support with anything but a gut feeling. Now every year that doesn't produce a cat 5 storm we will have to listen to a bunch of morons tell us how it’s stupid to conserve energy.

Who knows what will happen as CO_2 levels increase? Personally, I would prefer not to find out.

Some specific responses to the article:

The other three global temperature records use a mix of satellite and land measurements, or satellite only, and they all show no warming since 2001 and a recent cooling.

I'm not sure what the scientific consensus is, but I thought warming was still observed and not controversial. I could be wrong. The IPCC report will have a reliable answer (with error bars) to this one.

The new ice cores show that in the past six global warmings over the past half a million years, the temperature rises occurred on average 800 years before the accompanying rise in atmospheric carbon. Which says something important about which was cause and which was effect.

I'm not sure I agree with this. Is he implying that new ice core data contradicts the old data? The dates were very accurate on the old data b/c they were counted BY HAND, and there were many stratiagraphic markers. How did they measure the CO_2 concentrations way back? I bet it is some complicated deductive process with lots of assumptions originating from some isotopic analysis of the ice, and I am quite skeptical that they could say anything definitive about which precedes which. Also, how does one explain the temp. rise associated with large eruptions w/o invoking the greenhouse mechanism?

Land-based temperature readings are corrupted by the "urban heat island" effect: urban areas encroaching on thermometer stations warm the micro-climate around the thermometer, due to vegetation changes, concrete, cars, houses.

Ummm... what we want to measure is the actual temp. The 'micro-
climates' near urban areas contribute to the global average, too.

Cheers,

Micah