Global Warming Revisited

George Bush traveled to Europe and earned dog's abuse for his trust in space-based missile defense and his mistrust in the thesis that human generation of greenhouse gases is prompting the earth to heat up at an unacceptable rate. Lovely women in Gothenberg bared their rumps in protest. "Shield defense" is indeed an unworkable proposition. But (though doubtless for entirely misguided reasons) Bush is quite right to be mistrustful of the global warming thesis, as I discussed here back in March.

Let's take another look. Global warming has become a matter of theological conviction on the liberal left. Dispute the thesis and they want to burn you at the stake. As a way of indicating my all-round lowness of moral character and intellect, Katha Pollitt sent a tremulous e-mail to my CounterPunch co-editor Jeffrey St. Clair not so long ago, squawking that "someone who denies the existence of global warming is not just mistaken about one little fact among millions of facts, but is seriously warped, disingenuous, etc." To the contrary, I do believe in global warming. I just don't believe it's caused by humans. The world may well be on a long-term warming curve, just as the weather folk thought in the late 1930s, and thus returning to "normalcy," as it enjoyed two million years ago. Or the apparent recent trend may reverse itself in another quarter century, as Robert Essenhigh, a mechanical engineer at Ohio State, argues in a recent issue of Chemical Innovation, published by the American Chemical Society. Back in March there were headlines about a paper published in Nature that offered supposedly "the first direct evidence" (AP's phrase) that so-called greenhouse gases are building up in Earth's atmosphere and allowing less heat to escape into space. Remember the central premise of the greenhouse gas model of global warming: During daylight hours the Earth gets its huge heat input in the form of short infrared rays from the sun. In close balance, our turning globe releases this heat in the form of longer waves in infrared radiation during the night hours. In the greenhouse model, allegedly malign gases such as carbon dioxide (CO2) and methane happen to absorb the long infrared radiation more strongly. Thus these allegedly malign gases let the short infrared rays in, but when heat tries to escape each night, they hold it in the atmosphere. The more CO2 we humans create, the more cows we put to pasture and in feedlots belching out methane, the more heat is trapped and the hotter the world gets.

A team at London's Imperial College compared satellite readings of infrared light from Earth's surface and found less was escaping into space in 1997, specifically in the wavelengths known to be absorbed by greenhouse gases, such as carbon dioxide, methane and ozone.

"We're absolutely sure, there's no ambiguity: This shows the greenhouse effect is operating and what we are seeing can only be due to the increase in the gases," John Harries, the Imperial team's leader, said, carefully adding that the effect of clouds remains a huge ambiguity. The British study compared spectrometer readings from NASA's Nimbus 4 satellite taken from April 1970 to January 1971 and similar information collected from a Japanese satellite for about nine months in 1996-97. Only clear-sky readings of the atmosphere over the central Pacific were compared.

We've reproduced the crucial graph from that paper in Nature. It represents the "adjusted" temperature difference between observations in 1997 and 1970, based on measurements of the strength of the infrared energy radiating from the Central Pacific outward through the atmosphere and received at the spacecraft. It supposedly addresses exactly the core issue concerning so-called global warming: how much heat is being absorbed by greenhouse gases.

The numbers running vertically on the left are a Kelvin temperature scale (that is, a scale of infrared brightness) depicting the 1970 to 1997 difference in the heat escaping at each wavelength. So plus-5 means that there would be 5 degrees more heat emitted in 1997 than in 1970. Minus-5 would mean less heat was escaping in 1997 than in 1970, with this being ascribed by the Imperial College scientists to the dreaded man-made greenhouse gases. The claim these scientists make is that the extra heat being absorbed in 1997 by CO2 and methane is consistent with the independently measured increase in atmospheric CO2 and methane in the last 20 years.

The numbers along the bottom of the graph are points on an infrared spectrum, meaning wavelengths longer than what is visible: 800 represents far infrared, meaning the longest infrared waves, and therefore the farthest from visible. For example, if you look at coals on a barbecue, the actual radiant heat from the coals is invisible.

Going to the uppermost of the triplet of graphs, the scientists from Imperial College want us to focus on the regions of the spectrum containing the wavelengths where carbon dioxide and methane absorb heat. Readers will note that between 700 and 800 (the CO2 window) as well as between 1225 and 1325 (the methane window) there are downward spikes. The Imperial College gang take this to mean that more heat was absorbed and that therefore the global warming models are "confirmed."

Now we turn to my scientific advisor in these greenhouse and global warming matters, Pierre Sprey, a man knowledgeable about the often disastrous interface between environmental prediction and computer models.

Sprey: "All they've proved is that CO2 absorbs heat, and methane absorbs heat, something that could as easily have been demonstrated in a lab. Even worse, they're focusing only on the parts of the graph where carbon dioxide and methane absorb heat. Why the spikes they point to? Simply because emissions of carbon dioxide and methane were slightly higher in 1997 than 1970. But since CO2 and methane don't represent the bulk of the heat absorbed by the atmosphere those spikes cannot tell us whether the earth is cooling or warming. And in fact if you include the effect of water vapor, as shown in a different part of the graph, it appears that the earth was cooling over that period."

Again, remember that water is the single largest factor in the heating and cooling of the Earth. There is far more water in the atmosphere than CO2, and it absorbs a lot of infrared radiation. But from the computer modeler's point of view, atmospheric water in all its forms is very variable. Rain, they can't predict; clouds, they can't predict; humidity, they can't predict. All the greenhouse models fall down in this single inability to model the heating or cooling effects of water, whether in the form of humidity, clouds, ice, snow or ocean currents. The heart of the problem is that water is super complex. Take clouds. How much heat they absorb depends very much on the diameter of ice crystals, which no one knows very well. Clouds vary even more. Dark clouds absorb sunlight. White ones reflect it. So some clouds contribute to heating, some to cooling. That's why water is so maddening to modelers.

Now back to the graph. Sprey points out that if you look at the region in which water vapor absorbs heat, the most critical parts of the graph lie between 800 and 1000 and 1100 to 1200, precisely because these are the windows in which water does absorb heat. The reader will note that on the graph, both of those regions on the horizontal scale are positive, which means that in 1997 less heat was absorbed by the atmosphere than in 1970. Since the total positive area is much larger than in the total negative area in the CO2 and methane windows (those lunging but narrow downward spikes), the graph clearly shows that, overall, between 1970 and 1997 the atmosphere's water cooling effect was 2.5 times larger than the CO2-methane heating effect.

Ergo, the models have been disastrously contradicted.

Given the impossibility of modeling water, the Imperial College crew zealously avoided the inconvenient parts of the graph line. If they weren't so focused on the evil of justifying flimsy models, if they took all greenhouse gases into account, including water vapor, like Sprey they would have seen there's more heat being emitted from Earth in 1997 than in 1970.

Sprey: "Water fucks up everything. Their graph doesn't mean Earth is cooling. It just means that their model is screwed up. It could be that 1997 happened to have been less humid than 1970, a fact which the modelers ignore along with all the other water difficulties. And there are plenty of other problems with these data. For example they generated their graph from two entirely different infrared sensors, ones incompatible enough that people careful with infrared measurements would never dream of comparing the two sets. The sensible scientific thing would have been to do a hell of a lot of worldwide measuring of clouds, rain, ice, snow and humidity to get a real handle on cooling and warming."

Just as Bush was embarking on his trip to Europe he got hit with a report on global warming from the National Academy of Sciences, which generated more headlines about this being the final, ultimate, irrefutable proof of global warming. The NAS report sounded like the work of a lot of beard-strokers and placemen busy trying to sound objective, reviewing the work of their good friends and colleagues Intergovernmental Panel on Climate Change (excoriated here in March). But even the IPCC panel's report had to concede what it admitted to be a "very low" level of scientific understanding of an "aerosol indirect effect," one that could cool the climate system at a whopping rate of 2.35 watts for each square meter.

Aerosols are particles so fine they float in air. They can directly save the Earth from the sun's heat (as happens when volcanoes spew forth dust, provoking bad winters), though by how much is hard to predict with models. Even more uncertain is the effect of the seeding of clouds by aerosols, which we know can cause rain. The more rain we have, the less water vapor in the form of clouds, hence the less heat trapped by this water vapor. In a burst of honesty, the recent NAS report admitted that "climate forcing by anthropogenic aerosols is a large source of uncertainty about future climate change. On the basis of estimates of past climate forcings, it seems likely that aerosols, on a global average, have caused a negative climate forcing (cooling) that has tended to offset much of the positive forcing by greenhouse gasses. Even though aerosol distributions tend to be regional in scale, the forced climate response is expected to occur on larger, even hemispheric and global scales... Climate models that incorporate the aerosol-cloud physics suggest that these effects may produce a negative global forcing on the order of 1 watt per square meter [i.e. very substantial] or larger. The great uncertainty about indirect aerosol climate forcing presents a severe handicap both for the interpretation of past climate change and for future assessments of climate changes."

In other words, it's arguable that the more sulfate particles you put in the air, the more rain you cause, and the more you cool the Earth. You really want to live by a model that installs the coal industry as the savior of "global warming"?