20 percent drop in snow cover, seasonal changes and temperature increases add up to massive impacts
By Summit Voice
SUMMIT COUNTY — Global warming impacts in the Arctic are much more dramatic than predicted by many climate models, with summer temperatures the past few decades the highest in 2000 years, and a 20 percent decline in the amount of snow cover in May and June.
The winter season is already two weeks shorter than just a few decades ago and temperatures in the permafrost has climbed between .5 and 2 degrees, according to a team of Swedish researchers from Lund University, who compiled an extensive data set to draw a regional picture of the changes.
“The changes we see are dramatic. And they are not coincidental. The trends are unequivocal and deviate from the norm when compared with a longer term perspective,” said Margareta Johansson, one of the main authors of the new report.
The Arctic is one of the parts of the globe that has warmed the fastest. Measurements of air temperature show that the most recent five-year period has been the warmest since 1880, when monitoring began. Tree ring data show that the summer temperatures over the last decades have been the highest in 2000 years.
“There is no indication that the permafrost will not continue to thaw”, Johansson said. The report also addresses the issue of carbon stored in permafrost that could be released when it melts.
“Our data shows that there is significantly more than previously thought. There is approximately double the amount of carbon in the permafrost as there is in the atmosphere today”, she added.
The carbon comes from organic material that was “deep frozen” in the ground during the last ice age. As long as the ground is frozen, the carbon remains stable. But as the permafrost thaws, carbon dioxide and methane, a greenhouse gas more than 20 times more powerful than carbon dioxide, could be released, which could increase global warming.
“But it is also possible that the vegetation which will be able to grow when the ground thaws will absorb the carbon dioxide. We still know very little about this. With the knowledge we have today we cannot say for sure whether the thawing tundra will absorb or produce more greenhouse gases in the future”, Johansson said.
Effects of this type, so-called feedback effects, are of major significance for how extensive global warming will be in the future. Johansson and her colleagues present nine different feedback effects in their report. One of the most important factors is the reduction of the Arctic’s albedo. The decrease in the snow- and ice-covered surfaces means that less solar radiation is reflected back out into the atmosphere. It is absorbed instead, with temperatures rising as a result. Thus the Arctic has entered a stage where it is itself reinforcing climate change.
“It is clear that great changes are at hand. It is all happening in the Arctic right now. And what is happening there affects us all,” Johansson concluded.
The report, “Impacts of climate change on snow, water, ice and permafrost in the Arctic,” was compiled by about 200 polar researchers. It is the most comprehensive synthesis of knowledge about the Arctic that has been presented in the last six years. The work was organized by the Arctic Council’s working group for environmental monitoring (the Arctic Monitoring and Assessment Programme) and will serve as the basis for the IPCC’s fifth report, which is expected to be ready by 2014.
Besides Margareta Johansson, Torben Christensen from Lund University also took part in the work.
Filed under: climate and weather, Environment, global warming, seasons Tagged: | Arctic, Arctic global warming impacts, Environment, global warming, Greenhouse gas, Intergovernmental Panel on Climate Change, Lund University, permafrost, Summit County News