Missing fossils could warn of extreme climate to come.
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.
However, there has always been some doubt about the temperatures of the tropics during this period. Most paleo-climate records show that the tropics had mean annual temperatures of 28 to 33 °C, which is not much warmer than today.
Recently, however, better calibrated data have suggested that ocean temperatures could have soared as high as 41 °C.
If the tropics were indeed this hot, it would solve a huge problem faced by existing climate models, including those used by the Intergovernmental Panel on Climate Change (IPCC).
Existing models have difficulty duplicating climates in which the temperature gradient from the tropics to the poles is small, as suggested by the older paleo-climate data for the Eocene.