Arctic now reinforcing own warming

The effects of climate change in the Arctic are already here, says a 2011 study by 200 polar researchers, and those effects include a much-reduced covering of snow in the Arctic, a shorter winter season, and thawing tundra. Moreover, several feedback effects – including one where melting Arctic permafrost releases carbon to the atmosphere, and another where decreased snow and ice cover means more absorption of the sun’s heat into Arctic ground – are already happening to create faster warming than before, according to these researchers.

Overall, the new study suggests that changes in the Arctic are taking place significantly faster than previously expected, and that more changes can be expected. Scientists presented the new research on the Arctic at a conference in Copenhagen on May 4, 2011. Margareta Johansson, from Lund University, is one of the researchers who created the report, serving as editor of the two chapters on snow and permafrost. She said she believes the recent changes are part of a long-term warming trend.

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.

The report is called Impacts of Climate Change on Snow, Water, Ice and Permafrost in the Arctic. Close to 200 polar researchers contributed to the report, which these scientists call “the most comprehensive synthesis of knowledge about the Arctic that has been presented in the last six years.” The Arctic Council’s working group for environmental monitoring (the Arctic Monitoring and Assessment Program) organized the report, which will serve as the basis for the fifth report of the Intergovernmental Panel on Climate Change (IPCC), expected to be ready by 2014.

It has been known for some time that – over the past decades – Earth has not been warming uniformly. The polar latitudes appear to be warming faster than equatorial latitudes, for example. Measurements of air temperatures around the globe indicate that the most recent five-year period on Earth has been the warmest since 1880, when monitoring began. Other data, from tree rings and other indicators, show that summer temperatures over the last decades have been the highest in 2000 years.

In the Arctic, in the span of recent human memory and measurement, Arctic snow cover in May and June have decreased by close to 20 percent, the winter season has become almost two weeks shorter, and the temperature in Arctic permafrost has increased approximately half a degree to two degrees, according to this new report. Johansson said:

There is no indication that the permafrost will not continue to thaw.

The melting permafrost in the Arctic is expected to create a feedback loop, whereby even more carbon is released to the air. That is because large quantities of carbon are stored in the permafrost. Johansson said:

Our data shows that there is significantly more [carbon in Arctic permafrost] than previously thought. There is approximately double the amount of carbon in the permafrost as there is in the atmosphere today.

The carbon comes from organic material which 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, there is a risk that carbon dioxide and methane, a greenhouse gas more than 20 times more powerful than carbon dioxide, will be released, which could increase global warming. Johansson said:

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.

Feedback effects of this type are of major significance for how extensive global warming will be in the future, say these researchers. Margareta Johansson and her colleagues present nine different feedback effects in their report. In addition to the carbon released from melting permafrost, one of the most important right now is the reduction of the Arctic’s albedo, in other words, its brightness or reflectivity. The decrease in the snow-and-ice-covered surfaces means that the Arctic is not as reflective as it once was. Thus it reflects less solar radiation back out into the atmosphere. This radiation – essentially heat – is absorbed instead, with temperatures rising as a result. These researchers say the Arctic has entered a stage where it is itself reinforcing climate change.

The future does not look brighter, the researchers say. They point to climate models showing that temperatures will rise by a further 3 to 7 degrees. In Canada, the uppermost meters of permafrost will thaw on approximately one fifth of the surface currently covered by permafrost. The equivalent figure for Alaska is 57 percent. The length of the winter season and the snow coverage in the Arctic will continue to decrease, and the glaciers in the area will probably lose between 10 and 30 percent of their total mass – all this within this century, according to these researchers. They suggest there will be “grave consequences for the ecosystems, existing infrastructure and human living conditions.”

These researchers also say that new estimates indicate that by 2100 global sea level will have risen by between 0.9 and 1.6 meters (about 3 feet to about 5 feet), which is approximately twice the increase predicted by the U.N.’s panel on climate change, IPCC, in its 2007 report. This is largely due to the rapid melting of the Arctic icecap, they say. Between 2003 and 2008, the melting of the Arctic icecap accounted for 40 percent of the global rise in sea level. Johansson said:

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.

Bottom line: Some 200 polar researchers have released a new report called Impacts of Climate Change on Snow, Water, Ice and Permafrost in the Arctic. They presented results from this report at a climate conference in Copenhagen on May 4, 2011. The Arctic Council’s working group for environmental monitoring (the Arctic Monitoring and Assessment Program) organized the report, which will serve as the basis for the fifth report of the Intergovernmental Panel on Climate Change (IPCC), expected to be ready by 2014. The report suggests that the effects of global warming in the Arctic are now readily apparent and that feedback mechanisms are at work to increase warming: essentially, the Arctic is now reinforcing its own warming. Margareta Johansson, from Lund University, is one of the researchers behind the new report.

Via Lund University

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