Commentary

Holes in the Greenhouse Effect?

Global warming is about to heat up and enter the presidential sweepstakes for the year 2000. The fun starts in December, when the United States is going to agree to an amendment to the United Nations Framework Convention on Climate Change, also known as the “Rio Treaty,” that requires the signatories to reduce carbon dioxide emissions.

That’s the end of the easy part. Then the administration (read: Vice President Gore) is going to have to sell it to the Senate, which must approve treaties by a two-thirds majority. The amendment, which is likely to mandate a reduction of current emissions of between l0 percent and 20 percent by the year 2020; will carry an impressive price tag, perhaps several percent of gross national product per year by the time reductions become serious, according to several economists. It will first go to the Senate Foreign Relations Committee, chaired by Jesse Helms, the senior senator from North Carolina. Think it’s going to get out of there alive?

Along the way, Gore is going to have to confront a growing contingent of scientists who are increasingly unhappy with the glib forecasts of gloom and doom. Once dismissed as “a small but vocal band of skeptics,” usually supported by industry, the critics of the global warming thesis now have a rather formidable armada of facts.

As pointed out by Ross Gelbspan in The Washington Post four weeks ago, some of these scientists, myself included, enjoy industry research support. (In my case, 84 percent of my university research is funded by taxpayers.) His figures show an average of 835,000 per year to a few people. The U.S. government spends $2.1 billion per year on global change research and it’s hard to believe so much would be spent on researchers who would say “no problem.” Accepting Gelbspan’s contention that there are 2,000 climate scientists (there are actually about 60 PhDs in climatology in the entire United States), that’s a cool million dollars per scientist, every year. How could the vice president lose the global warming argument with these odds?

Easily. Arguments against highly deleterious global warming have a charm and internal consistency that the arguments of the critics— who emphasize caution and uncertainty— lack. It’s worthwhile to review the way the global warming thesis evolved. In 1990, the first Scientific Assessment of the United Nations Intergovernmental Panel on Climate Change (IPCC), a document that is the underpinning for the Rio Treaty, stated, “When the latest atmospheric models are run with the present atmospheric concentrations of greenhouse gases, their simulation of climate is generally realistic on large scales.”

Several critics cried foul. The “largest scale” of simulation of planetary climate is surely the average surface temperature, and it was apparent, even back in 1990, that the computer models used to simulate global warming were predicting much more warming than had been observed. Since then, it has become generally accepted that the “generally realistic” models were saying that it should have already warmed between 1.3 degrees and 2.3 degrees Celsius, globally, with the higher figure for the Northern Hemisphere. The observed warning of the earth’s surface temperature since the late 19th century is about one and a half of a degree. The first IPCC assessment is a busted forecast.

Why it took the U.N. five years to realize this is anyone’s guess, but it sure did generate a lot of frequent flier miles for skeptics like me. Finally, in their second Assessment, published in 1995, the IPCC admitted the skeptics had a point: “When increases in greenhouse gases only are taken into account …. most Climate models produce a greater mean warning than has been observed to date, unless a lower climate sensitivity [to the greenhouse effect changes] is used …. There is growing evidence that increases in sulfate aerosols are partially counteracting the [warming] due to increases in greenhouse gases.”

Sulfate aerosols are tiny bits of dust also emitted during the combustion of fossil fuel that cool global warning by reflecting away the sun’s radiation.

Translation of the 1995 report: Either it’s not going to warm up as much as we said it was, or something (like sulfate aerosol) is reducing the warming. I bet that many in my profession will do everything in their power to prove the latter and disparage the former, because no one wants to write the letter, “Dear Mr. Vice President: We are sorry but we goofed. Thanks for the $$. Hope you get your carbon tax. Yours truly, the Consensus of Scientists.”

Thus began a frantic effort to save face. Ben Santer, a fine and aggressive scientist from the Lawrence Livemmore Laboratory, published an article in Nature magazine last year that seemed to show a remarkable correspondence between the evolution of planetary temperature patterns and a model that included both the warming from the greenhouse gases and the cooling from sulfates. This result argued against the skeptics’ proposition that our planet was simply not prone to big-time warming. Santer’s study period began in 1962 and ended in 1987.

The critics immediately pointed out that the model he relied on had only half of the known changes in the greenhouse effect. The fact is critics and proponents of the global warming thesis agree that human activities like driving cars and burning coal have changed the amount of warming radiation in the atmosphere only about 2.5 watts (or about one-quarter the power of a good flashlight). The central issue is how much this affects the world’s climate.

Santer’s model had attempted to answer that question based on the assumption that the “change” in the amount of warming radiation was only 1.25 watts.

When the right number is put in to Santer’s model, things get even hotter than in the old models that were already abandoned. Worst of all, from Santer’s point of view, when all of the available data, which ran from 1958 through 1995, are used, the correspondence between the model and reality vanishes.

Then there’s the problem of the satellite measured temperatures. These measurements, accurate to .01 degrees Celsius, find a statistically significant cooling trend in the lower atmosphere since they started taking measurements in 1979. The old models, which the U.N. said in 1990 were “generally realistic,” predicted a warming of about .6 degrees Celsius since the satellite measuring started, and even newer models predict warming of .35 degrees of Celsius. This warming simply isn’t happening according to the satellite data.

The satellite data also match up perfectly, on a year-to-year basis, with temperatures measured in the lower atmosphere by weather balloons. This is a completely independent corroboration of the lack of predicted warming.

Then there’s the problem of identifying the type of warming that is going on. Warming up the planet’s coldest air masses clearly creates little harm, because no plant or animal can feel the difference between -40 degrees and -35 degrees. Greenhouse physics predicts that warming is more likely in the coldest air masses. Indeed, there is some evidence that this is already occurring in Siberia and northwestern North America in winter. But it’s no threat. It’s pretty hard to melt ice caps at temperatures that are way below freezing.

Conversely, a warm, humid air mass, where things are living and growing, doesn’t respond much at all to greenhouse changes. So we expect to see less change in the summer. In fact, most observed summer changes are either small or insignificant, even in Siberia. All totaled, the effects of winter warming and little summer change lengthens the growing season, costs less energy and is, in general, hard to label as a big negative.

Some people have made careers out of labeling what I just wrote as the carpings of that “small band of vocal skeptics.” I hope they read the May 16 issue of Science magazine. There, senior environmental reporter Richard Kerr found widespread discontent over the magnitude and even the detection of global warming. Kerr found, as predicted by the skeptics for 15 years now, that when climate models are cleansed of their “fudge factors” (his words) that they will produce precious little greenhouse warming in the next century.

Do this, and put in the most likely changes in the greenhouse effect for the next century, and you get 1.2 degrees Celsius of warming in a new climate model from the U.S. National Center for Atmospheric Research. From the new model of the United Kingdom Meteorological Organization, the same exercise will give you 1.3 degrees Celsius of warming. Or look at Tom Wigley’s completely independent calculation in Nature last year. Same number: 1.3 degrees.

The message is that this is less than half of the warming predicted by the U.N.’s “Consensus of Scientists” in 1990. And further, it’s now appreciated that most of this has to be in winter, as the rising temperature in Siberia is now informing us.

So the vice president is going to have to defend expensive and disruptive measures in the face of a very modest climate change whose most noticed effect will be to lengthen the growing season and reduce energy demand. The Senate will use the strength of the skeptics’ arguments to turn down any amendment to the Rio Treaty—which may actually be a blessing for Gore.

Defeat will enable the vice president to campaign in 1998 and 2000 on the attractive but spurious claim that Helms and the Republican leadership are going to kill our children because they won’t stop global warming. With global warming, as with Gore’s presidential ambitions, losing is winning.

Patrick Michaels is professor of environmental sciences at the University of Virginia and senior fellow in environmental studies at the Cato Institute.