The sediments depict the end of the Pliocene epoch
, which lasted from 5.3 million to 2.6 million years ago.
Using three independent methods--isotope analysis of fossil trees and mosses, analysis of the distribution of lipids in fossil soil bacteria and an inventory of ancient plant distributions--the scientists determined that although the mean annual temperature on Ellesmere Island during the Pliocene epoch
(2.6-5.3 million years ago) was about 19[degrees]C higher than today, carbon dioxide levels were only slightly higher than they are at present.
They discovered that melting took place repeatedly between five and three million years ago, during a geological period called Pliocene Epoch
, which may have caused sea levels to rise approximately ten metres.
Brigham-Grette added that the world at that time, known as the Pliocene Epoch
, had a similar proportion of carbon dioxide in the atmosphere as is recorded today.
The last time Earth's global C[O.sub.2] concentration was as high was during the Pliocene epoch
, 5.3 million to 2.6 million years ago, when summers in the Arctic were 8 degrees Celsius warmer than they are today.
During the Pliocene Epoch
, the status of sea levels 2.7 million to 3.2 million years ago, average global sea-surface temperatures at the time have been estimated to be about 3.6 to 5.2 degrees Fahrenheit (2 to 3 degrees Celsius) warmer than today.
The researchers say our upright gait may have its origins in the rugged landscape of East and South Africa which was shaped during the Pliocene epoch
by volcanoes and shifting tectonic plates.