In 1995, more than two thousand scientists from one hundred countries reported to the United Nations that our burning of oil, coal, and natural gas is changing the earth's climate. Nearly a decade later, many of the same researchers are very troubled by two things: The climate is changing much more quickly than they projected even a few years ago, and the systems of the planet are far more sensitive to even a very small degree of warming than they had realized. The average global temperature, the report said, will rise by 3 to 10º F by the end of the twenty-first century.
The accelerating rate of climate change is spelled out in two recent studies-one on the environmental side, one on the energy side.
In 2001, researchers at the Hadley Center, Britain's principal climate research institute, found that the climate will change 50 percent more quickly than was previously assumed. That is because earlier computer models calculated the impacts of a warming atmosphere on a relatively static biosphere. But when they factored in the warming that has already taken place, they found that the rate of change is compounding. Their projections show that many of the world's forests will begin to turn from sinks to sources-dying off and emitting carbon-by around 2040.
The other study, from the energy side, is equally troubling. Three years ago, a team of researchers reported in the journal Nature that unless the world obtains half its energy from noncarbon sources by 2018, we will see an inevitable doubling-and possible tripling-of