Sheffield scientists unlock a warning from pre-history

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PERIODS of global warming 55 million years ago released massive amounts of carbon trapped in frozen polar soil - and the same thing could happen again, according to Sheffield University scientists.

Thawing permafrost accelerated increasing global temperatures and acidification of the oceans - with temperatures rising by 5C in course of just a few thousand years.

A team from Sheffield analysed a series of sudden extreme global warming events - called hyperthermals - that occurred about 55 million years ago.

They were linked to rising greenhouse gas concentrations and changes in the Earth’s orbit.

Prof David Beerling said: “For the first time we have linked these past global warming events with a climatically sensitive terrestrial carbon reservoir. It shows that global warming can be amplified by carbon release from thawing permafrost.

“The research suggests that carbon stored in permafrost stocks today in the Arctic region is vulnerable to warming. Warming causes permafrost thaw and decomposition of organic matter releasing more greenhouse gases back into the atmosphere.

“This feedback loop could accelerate future warming. It means we must arrest carbon dioxide emissions released by the combustion of fossil fuels if humanity wishes to avoid triggering these sorts of feedbacks in our modern world.”

Colleague Rob DeConto said: “Global warming is degrading permafrost in the north polar regions, unlocking carbon and methane and releasing it into the atmosphere. This will only exacerbate future warming.”