Turns out severe global warming is not caused by man, sun spots or even the hot air expended by Keith Olbermann.
It’s the Earth’s orbit, according a new study by a climate scientist (I know, I know – climate science is to science as political science is to…) at UMass. From the Daily Mail:
The extreme warming events were called the Paleocene-Eocene Thermal Maximum (PETM) and took place over thousands of years.
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Previously it was thought that the oceans were the source of the carbon.
‘The standard hypothesis has been that the source of carbon was in the ocean, in the form of frozen methane gas in ocean-floor sediments,’ DeConto said.
‘We are instead ascribing the carbon source to the continents, in polar latitudes where permafrost can store massive amounts of carbon that can be released as carbon dioxide when the permafrost thaws.’
Many scientists have long suspected that rising levels of carbon dioxide and the global warming that ended the last Ice Age were somehow linked, but establishing a clear cause-and-effect relationship between carbon dioxide and global warming from the geologic record has remained difficult.
But a new study, published in Nature, identifies this relationship and provides compelling evidence that rising carbon dioxide caused much of the global warming.
Up to now carbon dioxide’s role was unclear because the Earth began warming before levels of the gas in the atmosphere began to rise.
But now Jeremy Shakun from Oregon State University has worked out what happened.
He believes that changes in the Earth’s orbit melted northern ice sheets, which meant that fresh water flowed into the Atlantic Ocean and stopped the circulation of warm currents.
‘When the heat transport stops, it cools the north and heat builds up in the Southern Hemisphere,’ Shakun said.
‘The warming of the Southern Ocean may have shifted the winds as well as melted sea ice, and eventually drawn the carbon dioxide out of the deep water, and released it into the atmosphere. That, in turn, would have amplified warming on a global scale.’
DeConto’s team used a new, high-precision geologic record from rocks in central Italy to show that the PETM occurred during periods when Earth’s orbit around the sun was both highly eccentric – non-circular – and oblique, or tilted.
BTW, to be clear – that’s PETM, not PETA.
MORE IMPORTANTLY… in case you missed it… the U.N.Intergovernmental Panel on Climate Change may have reversed itself on AGW. (Whatever you do, don’t tell Debbie Wasserman Schultz.)