(CN) – An official with the U.S. Environmental Protection Agency has released a study showing that Earth is warmer than it has been in about 120,000 years, and it is on pace to become the hottest it’s been in more than 2 million years.
In findings published Monday in the journal Nature, Carolyn Snyder presented a continuous temperature record for the last 2 million years, which goes well beyond the previously established 22,000 year record. However, estimated temperatures are not for specific years but instead are averages for 5,000-year time periods.
Snyder, a climate policy official at the EPA, based her estimates on 61 sea-surface temperature proxies from across the globe, including species makeup, acidity and ratios between magnesium and calcium. However, the further the study goes back in time, the fewer of those proxies are available to measure — especially after 500,000 years, she said.
The estimates also come with large margins of errors, but Snyder said the temperature changes correlate well to carbon dioxide levels.
Average temperatures over the past 5,000 years – including the last 125 years of industrial emissions of greenhouse gases – are generally warmer than at any time period in the past 120,000 years.
Two interglacial time periods, one about 120,000 years ago and another roughly 2 million years ago, were the warmest based on Snyder’s estimates.
After calculating past temperatures, Snyder applied her formulas to future trends, incorporating carbon dioxide levels and other factors and historical trends.
If climate factors are the same as in the past, which may or may not be the case, then Earth already faces another 7 degrees of warming over the next few thousand years, according to Snyder.
“This is based on what happened in the past,” Snyder said. “In the past it wasn’t humans messing with the atmosphere.”
Scientists have several theories for past changes in carbon dioxide and heat levels, including regular slight adjustments to Earth’s orbital tilt.
Michael Mann, a scientist at Pennsylvania State University’s department of meteorology, told the Associated Press that while Snyder’s findings are interesting, he wants more research to confirm her data.
He said Snyder’s future temperature calculations are “so much higher than prevailing estimates that one has to consider it somewhat of an outlier.”
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