WASHINGTON -- Referring to "Earth in the Balance," his 1992 compendium of environmental alarms, Al Gore recently said, "There's not a statement in that book that I don't endorse. Not one. The evidence has firmed up the positions I sketched there." Positions such as:

"The climate changes that we are now bringing about by modifying the global atmosphere are likely to dwarf completely the ones that caused the great subsistence crisis of 1816-19, for example, or those that set the stage for the Black Death," and "are likely to be five times larger than the fluctuations that produced the Little Ice Age, for example, or the global climate change that led to the Great Famine of 1315-17."Gore's eco-pessimism helped produce the 1997 Kyoto Protocol, which assigns to nations vastly different duties to reduce carbon emissions responsible for global warming. America's duty under this agreement (which the Senate is not about to ratify) would be to reduce carbon use by 550 million tons per year in 2010.

Before policymakers undertake trillions of dollars in abatement costs, they should consider a booklet published by American Enterprise Institute, "The Greening of Global Warming" by Robert Mendelsohn of the Yale School of Forestry and Environmental Studies.

He says that in the past decade our understanding of climate-change impacts has undergone a "near revolution" because the natural science and economic analyses underlying predictions have "altered dramatically." Ecologists are shifting from predictions of "ecosystem collapse" to long-term predictions that include benefits:

"These changes are so dramatic that it is not clear whether the net economic effects from climate change over the next century will be harmful or helpful. The new research further suggests that . . . many countries will benefit from warming."

Gore's 1992 strictures about global warming reflected the 1989 assessment by the Environmental Protection Agency, which influenced subsequent studies that concluded that damages from climate change would be, Mendelsohn says, "universal and devastating."

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The predicted (by the EPA) doubling of greenhouse gases was projected to produce temperature increases between 3 and 6 degrees Celsius. Sea levels would rise one meter, many tree species would disappear, and all animal species, and especially endangered ones, would be stressed. Sharp reductions of precipitation during growing seasons would be one reason why many crops would suffer 30 percent to 40 percent reductions in yields. Timber scarcities, increased water pollution -- the litany of woes was long.

Now improved analyses -- of the interaction of oceans and atmosphere, of the cooling effect of sulfates found in the atmospheres of Northern industrial countries, and much else -- support the conclusion that warming will be only 1 to 3.5 degrees Celsius. Precipitation will increase, as will many plants: The average crop would be 30 percent more productive with projected increases in carbon dioxide.

Never in recorded history have birthrates been as low, or per capita food production as high, as at the moment. Gore must pray for relief from the accumulating evidence that Earth is not really hanging in precarious balance.

Washington Post Writers Group

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