Ancient Climate Change Triggered Warming That Lasted Thousands of Years

An anonymous reader quotes a report from Phys.Org: A rapid rise in temperature on ancient Earth triggered a climate response that may have prolonged the warming for many thousands of years, according to scientists. Their study, published online in Nature Geoscience, provides new evidence of a climate feedback that could explain the long duration of the Paleocene-Eocene Thermal Maximum (PETM), which is considered the best analogue for modern climate change. The findings also suggest that climate change today could have long-lasting impacts on global temperature even if humans are able to curb greenhouse gas emissions.

Increased erosion during the PETM, approximately 56 million years ago, freed large amounts of fossil carbon stored in rocks and released enough carbon dioxide, a greenhouse gas, into the atmosphere to impact temperatures long term, researchers said. Scientists found evidence for the massive carbon release in coastal sediment fossil cores. They analyzed the samples using an innovative molecular technique that enabled them to trace how processes like erosion moved carbon in deep time. Global temperatures increased by about 9 to 14.4 degrees Fahrenheit during the PETM, radically changing conditions on Earth. Severe storms and flooding became more common, and the warm, wet weather led to increased erosion of rocks. As erosion wore down mountains over thousands of years, carbon was released from rocks and transported by rivers to oceans, where some was reburied in coastal sediments. Along the way, some of the carbon entered the atmosphere as greenhouse gas.

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