April 23, 2011 — andyextance

A decade-long study into the state of coasts in the Arctic has revealed that climate change is accelerating erosion there. The “State of the Arctic Coast 2010” report says that average erosion rates see coasts retreat half a metre per year, while some areas lose more than eight metres annually. That’s because, as sea-ice melts around the North Pole, larger exposed ocean areas enable the wind to whip up waves that damage the coastline more easily. However Hugues Lantuit, one of the editors of the report, underlines that without this specific scientific effort it would be hard to separate these effects from normal coastline erosion.

“The coast has always eroded, and there were always spectacular features in the coastal zone,” explained Lantuit, who works at the Alfred Wegener Institute for Polar and Marine Research in Potsdam, Germany. “In that sense, it is difficult to grasp the issue of climate change with the human eye. Data is necessary to complement it and to pinpoint to what is truly an impact of the climate and what isn’t. The climate has been warming dramatically in the Arctic, and the sea ice is retreating. The major challenge for us scientists is to quantify and link with precision the processes at work in the area. To do this, the human eye is often not enough.”

Satellites and local elders provide data



When Lantuit and his colleagues began their focussed study in 2000, detailed information was available for just one kilometre in every 200 on average along the Arctic coasts. “The data needed to compile this report has only been collected for a few decades in some cases, because of the remote location of the Arctic,” the scientist explained. “The scientific community needed time to get a mature and reliable set of observations to draw conclusions for the entire zone.”

However, just ten years of data would not be long enough to reach satisfactory conclusions. “Coastal erosion varies greatly from year to year and several decades of data are needed,” Lantuit said. “What is new here is that many investigators went back to old datasets, aerial photos, pictures from American spy satellites from the ’60s, and also observations from elders in local communities to trace erosion back in time. We are now in a position to comment on over fifty years of erosion, and more in some cases, which is helping us to assess the current trends.”

In February the researchers published details of the resulting database, containing information for over 100,000 kilometres of Arctic coastline or one kilometre in every four on average, in the scientific journal Estuaries and Coasts. That was followed by a full report of their research published this month. They found dramatic changes in the Russian coasts bordering the Laptev, and East Siberian Seas and the Alaskan and Canadian coasts on the Beaufort Sea. While many coastline areas are stable, these areas contributed the net average erosion the scientists report. Like two-thirds of the Arctic coastline, they are made up of unconsolidated sediment, which is only hard because it is frozen. These are rapid changes in a situation that has remained stable for millennia, they note, likely to have substantial effects on Arctic ecosystems near the coast and the population living there.

“Moving house” takes on a new meaning



“The loss of land threatens infrastructure, forcing buildings or even villages to relocate in some cases,” Lantuit explains. “Every loss of a building or relocation is costly in the Arctic, not only financially, but also because some of these buildings sometimes take up a great importance in the social network of the community. Industry infrastructure is also at stake – fisheries, oil and gas facilities are all located in coastal areas and can be affected by erosion.”

The main impact of coastal erosion on ecosystems comes because they deliver vast quantities of sediment and nutrients to areas near the shore. “Those are then immediately integrated in the food web,” Lantuit said. “With increasing erosion, the quantities of nutrients delivered to the coast will change and are likely to impact locally the food web and ultimately to affect the species of fish and even of mammals that are present in this zone.” Whether those impacts are positive or negative is currently unknown, the report notes.

Needing to understand the full consequences of erosion accompanies the scientists’ desire to expand the area of coastline they’ve covered, to be sure their findings are repeated elsewhere. “We have indications that coastal erosion has been dramatically increasing over the past few years from studies from Alaska, but we do not yet cover enough ground to assert this with certainty for the whole Arctic,” Lantuit said. “Every environmental parameter points, however, to a future increase of erosion.”