Sometimes I look with considerable interest at the global warming deniers because I think, for a brief moment, they may have found something of importance to say. So far, though, I always find that they are as dazed and confused as ever. This is the case with the recent salvo from self-proclaimed "rocket scientist" David Evans. David Evans claims expertise on global warming because of two things: his being a "rocket scientist" and his having previously done "carbon accounting" for the Australian government. Now ANYTIME someone tells you they are a "rocket scientist" it should be a red flag to you. I have never met anyone, including people who work for NASA, to identify themselves professionally as a "rocket scientist." Turns out Evans has a Ph.D. in Electrical Engineering and has not published a single peer-reviewed research paper on the subject of climate change. In fact he has published only a singlepaper in his entire career, and that was back in 1987 and had nothing to do with global warming. THis puts him on par with me vis a vis global warming: educated, smart and probably informed. I don't claim to be an expert in the field. Instead I cite experts in the field to support my claims. Evans himself claims to be an expert in the field despite having no real experience in climate change research.

Evans also claims to be a recent convert to denial, yet he is associated with an Australian global warming denial group (founded my a mining company executive) called the Lavoisier Group. Australian economist John Quiggin once commented that the Lavoisier Group is "devoted to the proposition that basic principles of physics...cease to apply when they come into conflict with the interests of the Australian coal industry." So take this mining industry connection into account when considering Evans' comments.

Look. They guy is probably smart. But engineering and bean-counting for the Australian government does NOT make you either a rocket scientist OR a climate expert.

But, he may still have a good understanding of the topic and merely be overstating his credentials. Hell, in my book, if he gets the science right then he is worth listening to even if he is being a tad untruthful about his qualifications.

Sadly, I quickly found his presentation of the science to be largely wrong. I was helped in blowing holes in his arguements by my wife (a climate sceintist at Columbia University) and this article on ScienceBlogs by Tim Lambert, a computer scientist at the University of New South Wales and hence somone with far more expertise than either David Evans or myself on computer modeling of climate. I am also trying to talk to people over at RealClimate.org, a forum for climate scientists for climate scientists, but have yet to hear back. But Tim Lambert's article essentially shows the actual data that soundly debunks Evans' claims.

Evans makes four points.

1 The greenhouse signature is missing. We have been looking and measuring for years, and cannot find it.

Each possible cause of global warming has a different pattern of where in the planet the warming occurs first and the most. The signature of an increased greenhouse effect is a hot spot about 10km up in the atmosphere over the tropics.

He makes an unsupported statement here that is the basis of this first point and probably the second point. Claiming that there is one definitive "signature" to look at is a big leap and any real scientist would give actual data for this. Specifically, anthropogenic global warming does NOT require the formation of "a hot spot about 10km up in the atmosphere over the tropics" according to my wife. She would be very interested in Evans' evidence for this, but you might notice he asserts it unsupported. That is unscientific. But what is interesting is Evans' claim for "a hot spot about 10km up in the atmosphere over the tropics" being the identifying characteristic of carbon dioxide-caused global warming is completely untrue. Tim Lambert's article shows two graphs, one based on models where carbon dioxide doubles and one based on models where solar output increases. Both show a hot spot. In reality, the defining feature of the carbon dioxide based model is stratospheric cooling. The hot spot is not the defining feature of carbon dioxide based models...stratospheric cooling is. And we have indeed detected stratospheric cooling, thus SUPPORTING the anthropogenic global warming model. In fact that stratospheric cooling for awhile masked ANOTHER prediction of the anthropogenic global warming models. The current models predict that surface warming would be accompanied by tropospheric warming. Satellite data (as I mention above) originially did not detect such a tropospheric warming. This was used by deniers as evidence against global warming, and was, in my mind, reasonable evidence. However, a couple of years ago this issue was resolved. The satellite data combined measurements from the stratosphere and troposphere in a way that was not at first appreciated, if I understand correctly. The new info came when these were separated. What was found was tropospheric warming AND stratospheric cooling, which are predictions of the current global warming models based on anthropogenic CO2 release. This is the kind of thing I mean when I say the predictions based on the anthropogenic global warming models are proving correct. Something as complex as surface warming, stratospheric cooling and tropospheric warming, have come true. By conrast the models based on increased solar output do NOT predict stratospheric cooling, so are less acurate. Evans was either showing his ignorance (being an engineer and bean-counter, not an actual climate scientist) or being outright dishonest here.

As to that hot spot (which is a more general prediction of global warming, not just carbon dioxide based global warming) this is discussed in the comments to Lambert's article: (comment by Joel Shore)

By the way, the hot spot in the upper atmosphere of the tropics is a basic result of moist adiabatic lapse rate theory, as Santer et al., [Editor's Note: See, Evans...this is what is called a citiation. Real scientists use them when arguing a point] pointed out. This is basically just a statement that when a parcel of air traveling upward in the atmosphere is saturated with water vapor, the warmer the air is to start with, the less rapidly its temperature drops as it rises through the atmosphere (because as the air expands and cools, the water vapor condenses out releasing latent heat warming the air...and more water vapor has to condense out for the warmer air than for the colder air). Because the warmer air cools more slowly, the difference in temperature gets magnified as you go up in the troposphere.

The Santer et al. paper showed that this expected magnification is in fact seen in the data for temperature fluctuations on monthly to yearly timescales. So, the observations on those timescales actually verify the model physics. It is only when one looks at the multidecadal trends in the data that one doesn't see the expected magnification (at least in some of the data sets). So, if there is any new physics coming in to mess up the agreement between models and observations, it has to come in on very long timescales...which seems rather difficult to imagine, since the convective processes that seem to be controlling the physics happen on much shorter timescales. (As a concrete example, the recent paper by Spencer et al. that purported to find some sort of negative feedback in the tropics was looking at timescales of days...so this mechanism can pretty much be immediately ruled out as a solution to such a discrepancy.)

Emphasis and Editor's Note mine.

Now turning to Evans' second point.

2 There is no evidence to support the idea that carbon emissions cause significant global warming. None. There is plenty of evidence that global warming has occurred, and theory suggests that carbon emissions should raise temperatures (though by how much is hotly disputed) but there are no observations by anyone that implicate carbon emissions as a significant cause of the recent global warming.

This is a bit silly. Or, as Lambert puts it, "outright denial." I always assert that the physics behind how any particular gas affects the absorption of heat and affects the greenhouse effect is pretty well worked out. We know that if you put more carbon dioxide into the atmosphere you WILL get warming. We have put more carbon into the atmosphere and we have seen a warming trend that matches the curve of increased CO2 very nicely. There is no other source of CO2 or methane or anything that has changed over the same time period with the same dynamics. But CO2 and warming match very well and we know the CO2 we are putting into the air. Occam's razor (NOT a scientific principle, mind you, but a convenient tool) suggests we explore the CO2 warming idea first.

Lambert, being a computer guy, goes to a comparison of warming models with and without anthropogenic factors. The blue bands on each graph show temperature changes modelled using only natural effects, while the pink bands include anthropogenic effects (the carbon dioxide we have put into the atmosphere). The black line shows actual observations (the raw data that scientists have to pay attention to). The observations fit the model where anthropogenic carbon dioxide is a factor.

This is very clear from this figure. And it is in line with the prediction from pure physics that if you pump more carbon dioxide into the air you WILL get warming. And it directly contradicts Evans' second point. Again, is this ignorance because Evans isn't an engineer and bean-counter, not a scientist, or is Evans deliberately dishonest here?

On to Evans' third point. Here he has several components, all of which are based on the criticism that the anthropogenic global warming models only use incomplete data to make their point. Again, this is demonstrably not true.

He first claims that anthropogenic global warming is based mostly on surface data and this is "corrupted" by the urban heat island effect, which is where the city itself for various reasons creates an "island" of warmth. My wife laughed at this. Simply put the "urban heat island" thing is a red herring. Climatologists have been well aware of this and have taken it into account for years now. Even I know this, so Evans certainly should. The surface measurements are NOT corrupted by the heat islands. They are corrected for it.

Then Evans makes the old arguement that satellite data doesn't support global warming. That went out the window when the stratospheric and tropospheric measurements could be properly separated, as I outline above. Since then the tropospheric and ground measurements agree well, with stratospheric cooling indicating that the warming is due to carbon dioxide.

Finally, Evans' claim that the anthropogenic global warming theory doesn't include ocean measurements is also untrue, as shown by Lambert. He points out the title of this well known NASA temperature graph:

What part of "Land-ocean" index suggests to Evans that the data only looks at land based measurements? Again, is Evans unaware of the current data or is he deliberately misleading? Onto Evans' fourth point:

4 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.

My wife really laughed at this claim. No one...NO ONE claims to be able to use ice core data to pinpoint cause and effect within an 800 year time frame. Current warming of course is not judged by ice core measurements, but the half a million year record that provides context does depend on ice cores. Ice core data is not precise enough to make the claim Evans does about cause and effect. No one can say anything about which is cause and which is effect from ice cores, so his fourth point is completely invalid. Evans' claim is further refuted here. He is probably just looking at a graph without taking into account the statistical error, so he is assuming a precision of the timing of events that is misleading him. I guess that is the kind of error an engineer or accountant might make, but not a scientist.

Overall this Evans crap is no more convincing than that dumb denial "documentary" The Global Warming Swindle. I had actually hoped for better. Science is advanced by discussing and exploring alternate hypotheses. But this can only be done using an honest approach to the data. In every single case I have observed the denial lobby does not do this. Evans is one more example of that.

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