Upsala Glacier: William L. Stefanov, NASA-JSC
It may seem that the Earth has always looked like it does now. It didn’t change much over the last centuries. How can one tell what the climate was like on Earth thousands and millions years ago? Was it hotter or cooler than now? What do the ice cores tell us? Was carbon dioxide involved in any way in shaping the climates of the past? Or, are the emissions of greenhouse gases changing the climate only now? What was driving climate change since humans were not burning fossil fuels? Where did the CO2 come from at that time?
Richard Alley is a geologist at the Penn State University, and the author of the “Two-Mile Time Machine”. He recently gave a talk at the meeting of the geophysicists. Geology may seem to be a little…erm… boring, however, when Richard talks about it, it is as lively as a basketball match. Studying climate these days can be an exciting and sometimes even dangerous occupation – when James Hansen, a climatologist from Goddard Institute for Space Studies, gave a talk couple of weeks ago in Houston, Texas, he was escorted to the hotel by the police, over concerns for his safety.
Anyway, ladies and gentlemen, here is Richard Alley: