A delicate balance

摘要

Earth has warmed rapidly before. About 55 million years ago, the temperature of the planet rose by as much as 8 ℃ over 20,000 years and remained elevated for roughly 100,000 years. The cause is unknown, but it may have been a result of cage-like methane clathrate molecules in the sea floor destabilizing and releasing into the atmosphere huge amounts of greenhouse gas.