The paleo-climate record shows very rapid periods of cooling in the past, when temperatures have dropped by as much as 18 degrees Fahrenheit (10 degrees Celsius) in a matter of years to decades, “the rate of warming we are seeing [now] is unprecedented in human history,” said Cornell oceanographer Charles Greene, the lead author of the paper appearing in the November 2008 issue of the journal Ecology, which is published by the Ecological Society of America. more »