As the Arctic warms and sea ice cover retreats, the erosion of permafrost coastlines is accelerating, scientists with NASA, the USGS and academic institutions say. In addition to the social and economic effects of receding Arctic shores, research published in the January edition of Nature Climate Change suggests that climate-driven coastal erosion may have a significant impact on Arctic marine life.
As a permafrost shoreline melts, blocks break off and slide into the sea, much like a glacier calving into a lake. Satellite imagery from LANDSAT shows that areas of Alaska's North Slope have lost half a mile of permafrost to seaward over the past 50 years. On Herschel Island in the Canadian Arctic, the sea is now consuming more than a foot every week, says Dr. Michael Fritz, a researcher with the Alfred Wegener Institute's Helmholtz Centre for Polar and Marine Research. The earth masses removed in this process release nutrients and pollutants into shallow waters, and the consequences for marine in the coastal zone are virtually unknown, Fritz says.
Along with sediment and organic carbon, permafrost is laden with naturally occuring fertilizers like nitrogen and phosphorus, which can cause algae blooms in seawater. In some places, the soil also contains natural deposits of heavy metals like mercury. When tundra slides into the sea, AWI's researchers say, the organic matter decays, releasing greenhouse gases and raising the pH of tidal waters. The sediments are deposited or transported out to sea.
These processes will likely accelerate as a result of rising temperatures, rising sea levels the shrinking of the protective sea ice cover, according to AWI's Dr. Hugues Lantuit, a co-author of the study. The rapid erosion may alter the food web in the coastal zone, affecting Arctic indigenous communities that depend on fishing to sustain their way of life.
The authors called for additional resources to study the effects of permafrost coastal erosion. “Politics and science must find common solutions here, for example within the framework of the EU research program Horizon 2020. In order to make concrete statements on the consequences of erosion, we need an interdisciplinary research program that includes policy-makers and the Arctic population from the beginning,” said Dr. Fritz.
In addition to the potential harm to coastal fisheries and marine life, permafrost deterioration can affect shoreside infrastructure like highways, airports and oil and gas pipelines. Beyond local effects, anticipated greenhouse gas emissions from permafrost decay are expected to add about 13 percent ($43 trillion) to the worldwide economic cost of climate change.