Climate Change - The Pliocene Rebooted?

Atmospheric carbon dioxide concentration is now over 400 parts per million (ppm).
It last reached similar levels during the Pliocene, 5.3-2.6 million years ago.


During this period, the area around the North Pole was much warmer and wetter than it is now.



Summer temperatures in the Arctic were around 15 degrees C, which is about 8 degrees C warmer than they are now.

Global average temperatures were 2-3°C warmer than today.

Of course, there were no modern humans at that time.



Hominids of the Pliocene

Nor was there a global system of food supply relying on stable climates for agriculture.


For more on research into the climate of the Pliocene, and what it can tell us about the likely effects of 400 ppm CO2, "Science News" has a very good article.  


Another paper: "Pliocene and Eocene provide best analogs for near-future climates" - Burke et al, 2018 makes these points:
"We are effectively rewinding the climate clock by approximately 50 million years,reversing a multimillion year cooling trend in less than two centuries."
 "by 2030 CE, future climates most closely resemble Mid-Pliocene climates, and by 2150 CE, they most closely resemble Eocene climates."

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