Even if by some miracle of environmental activism, global carbon-dioxide levels reverted to pre-industrial levels, it still would take 1,000 years or longer for the climate changes already triggered to be reversed, scientists said Monday.
The gas that is already there and the heat that has been absorbed by the ocean will exert their effects for centuries, according to the analysis, published Monday in the Proceedings of the National Academy of Science.
Over the long haul, the warming will melt the polar ice caps more than previously had been estimated, raising ocean levels substantially, the report said.
And changes in rainfall patterns will bring droughts comparable to those that caused the 1930s Dust Bowl to the American Southwest, southern Europe, northern Africa and western Australia.
“People have imagined that if we stopped emitting carbon dioxide, the climate would go back to normal in 100 years, 200 years,” lead author Susan Sol omon, a senior scientist at the National Oceanic and Atmospheric Administration in Boulder, said in a telephone news conference. “That’s not true.”
The changes will persist until at least the year 3000, said Solomon, who conducted the study with colleagues in Switzerland and France.
Scientists familiar with the report said it emphasizes the need for immediate action to control emissions.
Kevin Trenberth, head of climate analysis at the National Center for Atmospheric Research in Boulder, said the persistence of climate change caused by global warming “is poorly appreciated by policymakers and the general public, and it is real.”
“The policy relevance is clear: We need to act sooner, even if there is some doubt about exactly what will happen, because by the time the public and policymakers really realize the changes are here, it is far too late to do anything about it,” he added.
