Arctic region was permafrost-free when global temperatures were 4.5˚C higher than today, study reveals

Permafrost in the Cretaceous supergreenhouse

Earth’s climate during the last 4.6 billion years has changed repeatedly between cold (icehouse) and warm (greenhouse) conditions. The hottest conditions (supergreenhouse) are widely assumed to have lacked an active cryosphere. Here we show that during the archetypal supergreenhouse Cretaceous Earth, an active cryosphere with permafrost existed in Chinese plateau deserts (astrochonological age ca. 132.49–132.17 Ma), and that a modern analogue fo…

Arctic region was permafrost-free when global temperatures were 4.5˚C higher than today, study reveals

Scientists have found evidence that the Asian continent was free of permafrost all the way to its northerly coast with the Arctic Ocean when Earth's average temperature was 4.5˚C warmer than today, suggesting that the whole Northern Hemisphere would have also been free of permafrost at the time.

Environmental News Network - Research Reveals Arctic Region Was Permafrost-Free When Global Temperatures Were 4.5˚C Higher Than Today

Scientists have found evidence that the Asian continent was free of permafrost all the way to its northerly coast with the Arctic Ocean when Earth’s average temperature was 4.5˚ C warmer than today, suggesting that the whole Northern Hemisphere would have also been free of permafrost at the time.