As delegates from 180 nations meet in Milan, Italy to discuss ways to reduce greenhouse gases, the dean of Duke University's Nicholas School of the Environment and Earth Sciences said "there is overwhelming scientific consensus that greenhouse gases are increasing in Earth's atmosphere, that they will cause global warming, and that the evidence for warming is upon us."

"This is about as certain as any scientific consensus has ever been -- rivaling the early prediction that cigarette smoking was a cause of lung cancer," said William Schlesinger, the James B. Duke Professor of Biogeochemistry.

Schlesinger, an ecologist who has studied how increasing amounts of carbon dioxide affect trees and plants, said the evidence is clear that humans are causing global warming by emitting large amounts of gases like carbon dioxide that can trap solar heat like a greenhouse does.

While the 12-day United Nations conference in Milan proceeds, Russia is threatening to refuse to ratify the Kyoto Protocol that required cuts in such gases. The Bush administration has already rejected that international pact, citing economic effects, the exemption of Third World countries and scientific uncertainty.

"Unfortunately, delay works very much against us," said Schlesinger, a nationally recognized expert on global warming. "It will take centuries to remove carbon dioxide from Earth's atmosphere, and the longer we wait, the worse the problem becomes."

Under the Kyoto Protocol, nations like the United States that exceed the treaty's emissions limits would be able to purchase "credits" for those excesses from nations like Russia that have lesser outputs.

"Kyoto presents a lot of business opportunities, especially encouraging increased efficiency of energy use," Schlesinger said. "My suspicion is that without leadership of the United States on issues of global climate change, there is no compelling reason for Russia to feel they should sign onto Kyoto."

Schlesinger can be reached for additional comment at (919) 613-8004 or by email.