The climate of the Eocene ocean

Oxygen isotope palaeotemperature estimates are presented for a number of deep sea sediment samples of Eocene age, covering a wide geographical area. These are plotted on a geographical reconstruction for 50 Ma. The latitudinal temperature gradient at that time was less than half its present value: surface temperature at high latitudes was about 10°C, and at low latitudes little over 20°C. It is concluded that Ocean currents must have contributed a greater proportion of the poleward transport of heat than they do at present.