Friday, April 19, 2013

More Evidence of Historic Arctic Warming: Lake Sediment and Ice Cores

The Arctic is getting warmer and the implications for the entire Earth are dramatic. In addition to impacts on local wildlife and local peoples, Arctic warming is altering the climate around the world. It has been widely documented that Arctic sea ice is at historic lows. Research also shows that Arctic summers are warmer than they have been in six centuries and the North Atlantic current is warmer than it has been for almost two thousand years.

Arctic Summers are the Hottest they have been in Six Centuries

The past several summers in the Arctic have been the warmest in at least 600 years, according to a new study published in Nature. According to research by Harvard University, a combination of temperature readings, ice cores, lake sediments and trees indicate that the summers of 2005, 2007, 2010 and 2011 were all warmer than any previous summer in the past 600 years. The summer of 2010 was most likely the warmest ever recorded in western Russia, the Canadian Arctic and western Greenland.

"What we are trying to do is put statistical inference of past changes in temperature on a more solid and complete footing," said Martin Tingley, one of the authors of the study. "The [ice core, tree and lake sediment records], unlike thermometers, generally only give information about seasonal average temperatures, and we have not explored changes in variability at the daily and weekly timescales."

Tingley says that recent extreme events, such as the 2010 Russian heat wave and the 2003 heat wave ,are likely to become more common if the trend persists.

"These results suggest that the hottest summers will track along with increases in mean temperature," he said. As temperatures continue shifting higher, "then the probability of extreme events would go up even more rapidly."

High Arctic Norwegian Summers are the Hottest they have been in Almost Two Millennia

According to a new study, summer temperatures on the Norwegian archipelago of Svalbard in the High Arctic are now higher than during any time over the last 1,800 years.

These results were derived from an analysis of algae buried in deep lake sediments. Their findings reveal that since 1987, summer temperatures in Svalbard have been 2 to 2.5 degrees Celsius (3.6 to 4.5 degrees F) warmer than during the Medieval Warm Period, which lasted from roughly 950 to 1250 AD.

The Medieval Warm Period is often cited by climate change skeptics as proof that the planet has experienced periods of high temperatures in recent centuries unrelated to the burning of fossil fuels. "Our record indicates that recent summer temperatures on Svalbard are greater than even the warmest periods at that time," said William D'Andrea, a climate scientist at Columbia University. The algae, which make more unsaturated fats in colder periods and more saturated fats in warmer periods, reveal critical clues about past climates.

The North Atlantic current flowing into the Arctic Ocean is warmer than for at least 2,000 years. Scientists said that waters at the northern end of the Gulf Stream, between Greenland and the Norwegian archipelago of Svalbard, averaged 6 degrees Celsius (42.80F) in recent summers.

"The temperature is unprecedented in the past 2,000 years," lead author Robert Spielhagen of the Academy of Sciences, Humanities and Literature in Mainz, Germany.

The summer water temperatures, reconstructed from the makeup of tiny organisms buried in sediments in the Fram strait (the main carrier of ocean heat to the Arctic), have risen from an average 5.2 degrees Celsius (41.36F) from 1890-2007 and about 3.4C (38.12F) in the previous 1,900 years.

"We found that modern Fram Strait water temperatures are well outside the natural bounds," Thomas Marchitto, of the University of Colorado at Boulder, one of the authors, said in a statement.

This research is yet more supporting evidence for anthropogenic global warming that is melting sea ice at the North Pole. Most scientists have indicated that the disappearance of  Arctic sea ice has profound global consequences.

© 2013, Richard Matthews. All rights reserved.

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Why the Fate of the Arctic Should be of Concern to Us All
Its Official Arctic Sea Ice is at its Lowest Level in Recorded History
Melting Arctic Ice is Releasing Massive Amounts of Methane
The Arctic's Dangerous Combination of Environmental Toxicity and Genetic Vulnerability

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