The Associated Press

RIVERSIDE, Calif. — Global warming could release long-dormant stores of methane gas trapped beneath the Arctic permafrost — causing an abrupt and catastrophic climate change like one that occurred 635 million years ago that ended the last great ice age, University of California-Riverside researchers have determined.

Back then, the sheets of ice that covered Earth started to collapse, releasing methane gas that warmed the planet and caused the ice to retreat over a period of 100 to 1,000 years, said Martin Kennedy, a geology professor in UCR’s Department of Earth Sciences who led the research team.

“It was the greatest global-warming event of Earth’s history almost certainly,” he said.

Kennedy suggests the same kind of warming could be about to occur, not over hundreds of years but within a human lifetime.

The findings are published in the latest issue of science journal Nature.

The current trend of accelerated permafrost melting as the Arctic warms faster than other areas of the planet could release vast amounts of methane into the atmosphere, triggering rapid climate change.

Methane is 25 times more potent as a greenhouse gas as carbon dioxide.

Research indicates that 10,000 gigatons of frozen methane are currently stored in the world’s oceans and permafrost.

Kennedy worries that rising carbon-dioxide levels could drive enough warming to destabilize the stored methane reserves.

“Unzippering the methane reservoir could potentially warm the Earth tens of degrees, and the mechanism could be geologically very rapid.” Kennedy wrote.

“It doesn’t make one feel a lot better about the future,” Kennedy said.

Rapid climate change could cause the collapse of the Greenland ice sheet. The sea level would rise about 20 feet, inundating major coastal cities.

Accompanying drought could lead to crop failures and widespread famine, he said.