Discussion of climate change today makes people think global warming. About 13,000 years ago, though, Earth’s climate shifted abruptly in the other direction. Temperatures dropped 14 degrees Fahrenheit on average in parts of the Northern Hemisphere within just a couple of years.

Scientists have different ideas why, but evidence is mounting that the crash of an asteroid or comet into our planet triggered the cooling. University of South Carolina archaeologist Christopher Moore examined the muck from the bottom of a nearby lake for clues about what could have caused the temperature drop. What he found in the sediment layers – some of which had been down there at least 20,000 years – adds support to the idea that an extraterrestrial impact is to blame.

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The muck that’s been accumulating at the bottom of this lake for 20,000 years is like a climate time capsule. Christopher R. Moore

New evidence that an extraterrestrial collision 12,800 years ago triggered an abrupt climate change for Earth

Christopher R. Moore, University of South Carolina

Why did Earth's climate rapidly cool 12,800 years ago? Evidence is mounting that a comet or asteroid collision is to blame, with new support coming from the bottom of a South Carolina lake.

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