Did the tropics overheat during the Eocene some 55 to 34 million years ago? The answer holds the key to how our planet will respond to global warming, according to one climate researcher.

The Earth went through a prolonged phase of extremely high temperatures during the Eocene, in which even the poles were ice-free.


Recently, however, better calibrated data have suggested that ocean temperatures could have soared as high as 41 °C.

...If the tropics really were much hotter during the Eocene, it could have serious implications for future climate change since the same thing could happen again.

"If that's the case then we can't rely on some magical, benevolent thermostat that is just going to kick in and keep the tropics from heating up," says climate modeller Matthew Huber of Purdue University in Lafayette, Indiana.

... If ocean-surface temperatures during the Eocene were on the high end of what is suggested by paleo-climate records – 35 to 41 °C – then temperatures in the interior of continents in the tropics would have been up to 10 °C higher (125°F). This would most certainly have killed off any plants, says Huber.