Global warming could wipe out most species - study

By Michael Kahn

LONDON (Reuters) - Rising temperatures could wipe out more than half of the earth's species in the next few centuries, according to researchers who published a study on Wednesday linking climate change to past mass extinctions.

Researchers at the University of York said their study was the first to examine the relationship between climate, extinction rates and biodiversity over a long period.

The findings, published in the Proceedings of the Royal Society, suggest climate change was the cause of large-scale extinctions, said Peter Mayhew, an ecologist who worked on the study.

The study analysed fossil records and temperature changes over 500 million years, and found that three of the four biggest extinctions -- defined as when more than 50 percent of species disappeared -- occurred during periods of high temperatures.

"The relationship is true for the whole period in general," Mayhew said in a telephone interview. "If temperatures went up, then extinctions went up and biodiversity tended to be lower."

The U.N. Intergovernmental Panel on Climate Change predicts that average global temperatures are likely to rise by between 1.8 and 4 degrees Celsius by the end of the century, partly as a result of greenhouse gas emissions.

The upper end of the forecast rise would heat the earth close to the temperatures of 250 million years ago, when 95 percent of all animal and plant species became extinct, Mayhew said.

Some of the past mass extinctions happened over a brief few hundred years, providing evidence that present day rapid temperature rises could have the same impact, Mayhew said.

"It does give us an idea of what to expect in the near future," he said. "There is nothing that says it couldn't happen in a short timescale."