Climate change warming the bench

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Last week, as Washington floated away in a summer torrent that reporters glibly blamed on global warming, the Supreme Court agreed to hear Massachusetts v. Environmental Protection Agency, the mother of all climate changes cases.

The case represents a proceeding of several state attorneys general, environmental groups and others arguing current law requires the federal government to classify carbon dioxide -- the main global warming gas -- as a "pollutant."

But is carbon dioxide a "pollutant," a harmless byproduct of human activity, or even an adjuvant? No one knows. There has never been a truly comprehensive study of the net effects of powering our world on fossil fuels.

Here is one example of the complexity that the court will have to confront in deciding carbon dioxide's fate.

On one hand, a body of scientific research claims that, by spreading malaria, global warming kills 150,000 people each year. The logic is simple. Plasmodium falciparum (the responsible parasite) can be transmitted when temperatures exceed an average of 59 degrees and rainfall is greater than 6 inches for two consecutive months. So, rising global temperature will increase malaria, right?

Wrong. In a 2002 piece for the scientific journal Nature, Oxford University's Simon Hay writes that where malaria shows major increases -- in Kenya, for instance -- there is no associated temperature or precipitation trend. There also are plenty of places in the United States that meet the climatic criteria for malaria, but in which the disease is virtually absent. And in the 19th century, when global temperatures were about 1.4 degrees lower than now, malaria was endemic over most of the country, all the way up into Canada.

"Economic, social and political factors can therefore explain recent resurgences in malaria and other mosquito-borne diseases," Mr. Hay wrote, "with no need to invoke climate change."

Then there's the other side of the coin, rarely considered: How many lives have been saved in our carbon dioxide-emitting societies?

Since 1900, life expectancy in the industrialized Western world has roughly doubled. Assuming 2 billion people have passed through that world since, that's equivalent to saving a billion lives. But warming is largely attributable only to human activity since the mid-1970s, so by any estimate, the number of lives saved by our emitting societies is much greater than any cost.

Then there is the problem of adaptation. Static projections of global warming death and destruction assume what is known in my profession as the "stupid people hypothesis," which is that people will just sit around and slowly fry and die, without making any attempt to adapt through technological change.

That's a testable hypothesis. Our cities have been warming for decades (with or without global warming) because the bricks, buildings and pavement retain the sun's warmth. But as they have warmed, heat-related deaths have fallen. Indeed, in some large North American cities, there is no longer any significant association between hot weather and mortality. The same technology (electrically powered air conditioning) that emits "polluting" carbon dioxide also prolongs life and makes it more comfortable.

Other common assertions about global warming are on equally thin ice. For instance, average temperatures over Antarctica have fallen in recent decades, and snowfall has increased. Every modern computer model for 21st century climate change predicts Antarctica will continue to gain ice, lowering sea levels as a result.

Even as Al Gore tells us we have only 10 years left before certain disaster ensues, people continue leading longer, richer lives, thanks largely to a fossil fuel-powered economy and its technological base. Mr. Gore may rave on about rapid ice recession in Greenland resulting from a warming trend that began about eight years ago, but he never mentions it was warmer for decades in the early 20th century. If Greenland is sloughing ice now, think what it must have been doing back then, nearly a century ago.

At any rate, these are the issues the Supremes have to contend with. Somehow they're going to have to add up all these effects and conclude they have a net negative impact on society. Otherwise, they'll have to conclude carbon dioxide isn't a pollutant at all and shouldn't be regulated.

Patrick J. Michaels is senior fellow in environmental studies at the Cato Institute and professor of natural resources at Virginia Tech.