Forget Natural Variation: New Arctic Sediment Samples Show 20th Century Warming Unlike Past Events
Not the actual lake... photo: D. Sikes via flickr.
A new paper published in the Proceedings of the National Academy of Science further closes the door on the notion that current climate changes are just the result of natural variations, as have been seen in the past. Sediment samples from a remote Arctic lake, retrieved by researchers show "unprecedented" changes:Samples Go Back 200,000 Years
The sediment samples are unique in that, unlike it glaciated portions of the Arctic which only show climate clues of the past 10,000 years, these ones contain paleoclimatic information going back 200,000 years.
Jason Briner, assistant professor of geology at the University of Buffalo, says that "even though glaciers covered this lake, for various reason they did not erode it. The result is that we have a really long sequence or archive of sediment that has survived Arctic glaciation, and the data it contains is exceptional."
Recent Changes Different Than Ever Seen Before
The exceptional part is that while there are periods of time reflected in the samples that are as warm as the climate is today, caused by "well-understood patterns of the Earth's orbit around the sun." Today the samples indicated that the whole ecosystem has shifted, just in the past few decades, and is "different from those seen during any of the past warm intervals."
Briner noted that "the sediments from the mid-20th century were not all that different from previous warming intervals" but after that things changed and "the change is unprecedented."
Report lead author Yarrow Axford, research associate at the University of Colorado, added, "The 20th century is the only period during the past 200 millennia, in which aquatic indicators reflect increase warming, despite the declining effect of slow changes in the Earth's axis which, under natural conditions, would lead to climatic cooling."
More: Recent changes in a remote Arctic lake are unique within the past 200,000 years [subscription or pay-per-view required]
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