The past several summers in the Arctic have been the warmest in at least 600 years, according to a new study published in Nature.
Using records derived from temperature instrument readings, ice cores, lake sediments and trees, researchers at Harvard University found that there is at least a 95 percent chance 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, according to the study.
By using a series of records derived from multiple sources, Martin Tingley, one of the authors of the study, says scientists have gotten a clearer picture of temperature trends in the Arctic.
"What we are trying to do is put statistical inference of past changes in temperature on a more solid and complete footing," he said in a statement. "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."