March 12, 2009 -- Adding to the woes of polar ice-melt and shrinking glaciers, erosion rates have doubled along a stretch of the northern Alaska coast in the last 50 years, according to recent research. Most of that erosion has happened in just the last few years.
See the signs of climate change in Alaska in this video.
The study area, which borders the Beaufort Sea east of Barrow, is a unique place that doesn't necessarily reflect the pace of change throughout the Arctic. But warming trends are most likely to blame for the rapidly crumbling coastline and the drastic ecosystem changes that follow.
And what's happening along the shores of the Beaufort Sea might hint at what's to come in the rest of the Arctic, where a slower pace of erosion is harder to measure but equally important, said lead researcher Benjamin Jones, a geographer with the United States Geological Survey in Anchorage, Alaska.
"It's an extreme case," Jones said. "We can learn a lot from extreme cases."
Related Content:
The region is extreme in many ways. Instead of beaches, the Alaskan Beaufort coast consists of icy bluffs that dangle over the water.
There are no islands off shore, so strong, storm-driven waves can batter the bluffs and chip away at sediment-filled blocks of ice. And as soon as one block falls, water seeps in to chip away at the next block. All of this coastline bashing happens during the three or four months a year when the sea is ice-free.
In 2007, USGS geologist John Mars and colleagues used remote sensing data to measure the accelerating rate of erosion in the region, but the resolution of their images was low.
To get a better sense of just how fast the coast was retreating, Jones and his team collected both old and new aerial photos of a 60-kilometer (37-mile) stretch of coastline. The images provided a much higher level of detail.
Results showed that, between 2002 and 2007, an average of 13.6 meters (45 feet) of shoreline disappeared each year, compared to an average annual retreat of 6.8 meters (22 feet) between 1955 and 1979, and an annual loss of 8.7 meters (28.5 feet) between 1979 and 2002.
In the summer of 2007, an astounding 25 meters (82 feet) of land fell into the sea in one spot. The images showed that most of the coast is eroding now, compared to fewer isolated sections of just certain types of shoreline in the past.
Researchers plan to closely monitor water temperature, sea level, and storms in the area from now on in order to figure out exactly what is responsible for quickening pace of erosion. It's possible, Jones speculated, that warmer sea surface temperatures are melting coastal ice more quickly. Warmer ground temperatures or stronger storms might also have something to do with it.
Whatever the cause, wildlife is already facing the consequences. Bird biologists have noticed a shift in the distribution of migratory geese, Jones said. And in one area, images from 1955 showed a freshwater lake near the shore. In 2005, the lake had been breached by salty seawater.
"All the animals and plants in that lake belonged to a freshwater ecosystem," Mars said. "By 2005, that has been completely replaced by another whole ecosystem. That's quite an impact."
Related Links:
our sites
video
mobile
shop
stay connected
corporate
