Hypothesis in policy-making

A crucial part of the debate over global warming-and one receiving too little attention in the run-up to next month's international meeting on the issue in Kyoto, Japan-is the role played in policy-making by hypothesis.

What international leaders seem ready to do in Kyoto is momentous. They would subject the world's people to an international treaty superseding sovereign governments. They would require major shifts in patterns of energy use. They would impose great costs and force people to make major changes in their lives. They might, by exempting developing countries, apportion the costs unequally.

And they would do all this in service to an hypothesis.

What's certain

Assertions of certainty about a warming threat are either uninformed or artful. Yes, the atmospheric concentration of carbon dioxide has risen. And average measured surface temperatures are higher now than they were 100 years ago. But to conclude from those observations that the world needs to change the way it works requires several lunges into hypothesis.

The argument for drastic remedies requires, for example, the unproved assertion that the past century's measured warming results from CO2 placed into the atmosphere by people burning fossil fuels and forests. The link is by no means clear. Most of the observed warming occurred before World War II; most of the CO2 build-up came afterward. Satellite measurements, offering much greater coverage than surface measurements do, show no warming in the 2 decades they have been available.

Surface temperatures fluctuate for reasons other than changing concentrations of greenhouse gases. Temperature cycles, in fact, correlate better with changes in solar activity than they do with CO2 levels. And the climate probably has temperature-balancing mechanisms that science cannot yet predict. Any projection of catastrophic warming based on a further CO2 build-up is an hypothesis not upheld by observation.

The case for drastic remedy further relies on the assumption that target CO2 emission reductions can make a difference. Recent studies indicate that only 3-4% of CO2 emissions come from human activity. Forced cuts in those emissions can have only tiny effects on the total.

At Kyoto, world leaders thus will discuss very costly adjustments to energy consumption in pursuit of relatively minor reductions in emissions of CO2. And they will have no assurance that the measures will influence global temperature at all. Why do they even bother?

The issue derives its energy from yet another hypothesis, behind which all the others stand dutifully in line. It asserts that imaginable consequences of warming are so dire that waiting for science to better understand climate phenomena is a luxury that humanity cannot afford.

The logic is stern: If there is even a chance for catastrophic warming, however small, prudence demands immediate precaution, however costly. And it excuses government officials from the rational deliberation and tough choices that once constituted leadership. Pandering to exaggerated fear is so much easier.

Are governments going to surrender sovereignty and dump costs onto the governed every time the mere chance of a threat emerges from the swirling mists of popular opinion? Do officials intend to sacrifice a measure of economic growth to every scary hypothesis that blares forth from the fund-raising campaigns of environmental groups?

Hypothesis and fear

Practitioners of the politics of fear now scoff at scientific questions about warming hypotheses. In the U.S., they question the patriotism of doubters.

So the stakes at Kyoto aren't just those embodied in the very reasonable hypothesis that whatever costs may be imposed will yield absolutely nothing measurable in global temperature. They also include the quality of debate and leadership that can be expected the next time a complex environmental subject frightens people.