A new study of the High Arctic climate roughly 50 million years ago led by the University of Colorado at Boulder helps to explain how ancient alligators and giant tortoises were able to thrive on Ellesmere Island well above the Arctic Circle, even as they endured six months of darkness each year.
The new study, which looked at temperatures during the early Eocene period 52 to 53 million years ago, also has implications for the impacts of future climate change as Arctic temperatures continue to rise, said University of Colorado at Boulder Associate Professor Jaelyn Eberle of the department of geological sciences, lead author of the study.
The team used a combination of oxygen isotope ratios from fossil bone and tooth enamel of mammals, fish and turtles that lived together on Ellesmere Island to estimate the average annual Eocene temperature for the site. They also were able to tease out temperature estimates for the warmest and coldest months of the year, critical data that should help scientists better understand past and future biodiversity in the High Arctic as the climate warms, including the geographical ranges and species richness of animals and plants.
The team concluded the average temperatures of the warmest month on Ellesmere Island during the early Eocene were from 66 to 68 degrees Fahrenheit (19-20 degrees C), while the coldest month temperature was about 32 to 38 degrees F (0-3.5 degrees C). "Our data gathered from multiple organisms indicate it probably did not get below freezing on Ellesmere Island during the early Eocene, which has some interesting implications," she said.
A paper on the subject was published in this month's issue of Earth and Planetary Science Letters. Co-authors included Henry Fricke from Colorado College, John Humphrey and Logan Hackett from the Colorado School of Mines, Michael Newbrey from University of Alberta, Edmonton, and Howard Hutchison from the University Californi
|Contact: Jaelyn Eberle|
University of Colorado at Boulder