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Group's Summary Overheats Warming Threat

Rhetoric doesn't match data

Kenneth Green
November 27, 2000

Every other November, groups representing governments, environmentalists, industry and others attend an international meeting to plan global warming policy. This year, they're meeting in the Hague.

Many people worry about disastrous changes in climate and see recent omens as troubling. Changing temperatures near the Earth's surface suggest the climate, largely stable for the last 10,000 years, is resuming older, more mercurial patterns. There's been a noticeable global warming trend during the last 100 years, and there's evidence suggesting that humanity may have caused some still-unknown portion of that increase by changing levels of forestation and by emitting greenhouse gases into the atmosphere.

But it's a big leap from a responsible concern about recent climate patterns to the heated rhetoric pouring out of the Hague rhetoric shaped by uncritical media coverage of a draft "summary for policymakers" leaked to the press in late October. The summary for policymakers supposedly reflects the authoritative 3,000-plus-page Assessment Report of the Intergovernmental Panel on Climate Change.

That worthy document is written by several hundred climate investigators and reviewed by several thousand other experts, myself included. The Assessment Report, updated every four years, is often said to reflect what "2,000 scientists think about global warming." The summary, on the other hand, is written by a few high-level members of the Intergovernmental Panel on Climate Change and is reviewed mainly by politicians.

Taking the leaked summary at face value, headlines have blared that scientists predict worse warming than before, with predicted future temperatures rising from the 4.5 degrees Centigrade of the last landmark report to a possible 6.5 degrees Centigrade of warming by 2100. This lends urgency to the mission in the Hague, we are told.

But the reported jump in predicted temperatures only appeared in the summary, not the underlying Assessment Report, and it only appeared in the last six months, long after the scientific review ended. Since the climate itself didn't change radically in the last six months, what accounts for the sudden increase in the forecast?

The answer lies in a sudden gust of questionable assumptions that blew into the modeling process six months ago, with limited expert review. Future climate predictions are produced with computer models incorporating thousands of assumptions about the future, including population rates, energy use levels, international economics and so on. These models have improved over the years, but like all computer models, there's a "garbage in, garbage out" problem.

Between April and October 2000, after the expert reviewers of the Assessment Report had done their work, a haphazardly formed sub-group came forward with the assumptions they would use for predicting future climate. One of these new sets of assumptions envisions the worst of all possible worlds, climate-wise, where energy use is profligate, where fossil-fuel use is maximized, and where people do absolutely nothing to improve things, even in the face of massive changes.

That gloomy scenario, cranked through simple climate models, produced the predictions of higher temperatures in 2100. Everything else, sea-level rise, ice melting, rainfall and storm predictions all flow from that one, post-review exercise.

But is this realistic? Consider three of the biggest underlying assumptions. One key assumption is that there will be no programs implemented between now and 2100, even in the face of predicted climate changes. Given that such programs are already being implemented in forestry and agriculture, this assumption can�t be right.

Another assumption is that the entire developing world will completely catch up to developed countries, and have the same per-capita income and energy demand. When you consider that the rich-poor gap has been going in precisely the opposite direction for the last hundred years, that assumption is highly unlikely.

A third assumption suggests that most energy production in 2100 will be from high-carbon fossil fuels, with only moderate advances in efficiency and emission control. Given that the entire history of energy use reflects more efficient use of lower-carbon fuels (particularly during the past 50 years) with sharply lower emissions per unit of energy, this assumption is highly unlikely.

It is only natural for people to be curious about the climate, and concerned about radical change.

By the same token, climate fears are easily inflamed, and humanity will not profit from acting on draft reports that pass off speculation for knowledge, and that sacrifice scientific credibility for political posturing.

Right now, in the Hague, 10,000 people are arguing about how to centrally plan the Earth's climate. The key document setting the tone is a leaked draft laced with unrealistic assumptions and misleadingly portrayed as reflecting "what 2,000 scientists think about global warming." That's more than vaguely unsettling.

Dr. Kenneth Green is senior fellow at Reason Foundation and Chief Scientist at Frasier Institute.



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