Indo-Asian News Service: An abrupt release of methane from ice sheets 635 million years ago triggered a spell of global warming, says a study that contends something similar is just waiting to happen. Researchers believe the greenhouse gas was released gradually and then abruptly from clathrates – methane ice that forms beneath polar ice sheets. The release had resulted in a series of cataclysmic events and ended the last Ice Age. These same methane clathrates are present today in the Arctic permafrost as …