As part of her doctoral dissertation at Stanford University, Carolyn Snyder, now a climate policy official at the U.S. Environmental Protection Agency, created a continuous 2 million year temperature record, much longer than a previous 22,000 year record.
Snyder based her reconstruction on 61 different sea surface temperature proxies from across the globe, such as ratios between magnesium and calcium, species makeup and acidity.
"Warmest in 120,000 years"
Temperatures averaged out over the most recent 5,000 years – which includes the last 125 years or so of industrial emissions of heat-trapping gases – are generally warmer than they have been since about 120,000 years ago or so, Snyder found.
She said if climate factors are the same as in the past -- and that's a big if -- Earth is already committed to another 7 degrees or so (about 4 degrees Celsius) of warming over the next few thousand years.
“This is based on what happened in the past,” Snyder said. “In the past it wasn’t humans messing with the atmosphere.”