An international team of scientists has found that changes in Earth’s orbit that favored hotter conditions may have helped trigger a rapid global warming event 56 million years ago known as the Paleocene-Eocene Thermal Maximum .
The team of scientists studied core samples from a well-preserved record of the PETM near the Maryland coast using astrochronology, a method of dating sedimentary layers based on orbital patterns that occur over long periods of time, known as Milankovitch cycles. “An orbital trigger may have led to the carbon release that caused several degrees of global warming during the PETM as opposed to what’s a more popular interpretation at the moment that massive volcanism released the carbon and triggered the event,” said Kump, the John Leone Dean in the College of Earth and Mineral Sciences., also indicated the onset of the PETM lasted about 6,000 years. Previous estimates have ranged from several years to tens of thousands of years.
“Those rates are close to an order of magnitude slower than the rate of carbon emissions today, so that is cause for some concern,” Kump said. “We are now emitting carbon at a rate that’s 5 to 10 times higher than our estimates of emissions during this geological event that left an indelible imprint on the planet 56 million years ago.”
“The reason there’s an expression in the geologic record of these orbital changes is because they affect climate,” Kump said. “And that affects how productive marine and terrestrial organisms are, how much rainfall there is, how much erosion there is on the continents, and therefore how much sediment is carried into the ocean environment.”
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