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Arctic Climate Especially Sensitive To Small Fluctuations In Carbon Dioxide Levels: A Study

May 09, 2013 05:37 PM EDT
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The Arctic was reportedly a “very warm” place during a period roughly 3.5 to 2 million years ago, a period that, research suggests, boasted levels of carbon dioxide comparable to today’s, according to a new National Science Foundation-funded study.

In fact, it was warm enough to have once been home to entire forests.

The finding, researchers argue, shows that even relatively small fluctuations in carbon dioxide levels can have a major influence on Arctic climate.

Furthermore, as Brigham-Grette stated in a NSF-issued press release, the discovery “could tell us where we are going in the near future.”

The study, led by Julie Brigham-Grette of the University of Massachusetts and published in the journal Science, represents an analysis of the longest terrestrial sediment core ever collected in the Arctic and “an exceptional window into environmental dynamics” that was previously impossible.

“While existing geologic records from the Arctic contain important hints about this time period, what we are presenting is the most continuous archive of information about past climate change from the entire Arctic borderlands,” Brigham-Gette said. “Like reading a detective novel, we can go back in time and reconstruct how the Arctic evolved with only a few pages missing here and there.”

Among the mysteries specifically addressed by the study is how the Arctic transformed from a forested landscape to the barren ice waste it is today.

The site of the drilling, Lake El’gygytgyn located in the northeast Russian Arctic, was formed 3.6 million years ago when a meteorite hit the Earth, blasting a whole nearly 11 miles wide. The lake bottom has been busy accumulating layers of sediment ever since.

Furthermore, the lake is situated in an area that was not eroded by continental ice sheets during ice ages, thus leaving a thick, continuous sediment record largely and almost miraculously undisturbed.

Among the fossil pollen found in the core was that belonging to Douglas fir and hemlock.

Furthermore, the specimen documents a period of sustained warmth in the Middle Pilocene, with summer temperatures averaging between 59 and 61 degrees Fahrenheit and precipitation levels three times higher.

“It is very impressive that summer temperatures during warm intervals even as late as 2.2 million years ago were always warmer than in our pre-Industrial reconstructions,” Brigham-Grette said regarding the observation.

Finally, the sediment core revealed to scientists that even during the first major “cold snap” to show up in the record some 3.3 million years ago, temperatures in the western Arctic were similar to recent averages of the past 12,000 years.

“Most importantly, conditions were not ‘glacial,’ raising new questions as to the timing of the first appearance of ice sheets in the Northern Hemisphere,” the authors add.

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