for National Geographic News
The sea is eating away at Alaska's northern coast with alarming speed, a new video of time-lapse photographs shows.
Although the Beaufort Sea coastline has been receding for millennia, a marked increase in the rate of erosion over the last century is a concern, scientists say.
A research team rigged a camera on top of a pipe wedged into the seafloor about 15 or 20 feet (4.6 to 6 meters) offshore.
The camera was set to photograph the coast several times every day for a little more than a month this summer, capturing the sea forming a hollow niche at the base of the bluff pictured.
After a large chunk of the bluff fell into the sea and was washed away within five days, the water continued to hollow out the niche and more chunks of land toppled off the bluff.
"A combination of likely factors are leading to this," said team member Benjamin Jones of the Alaska Science Center, part of the U.S. Geological Survey (USGS).
"It could be related to some of the changes that are happening and that have been reported in the Arctic, like declining sea ice in the summer and increasing sea temperatures."
Although rising sea levels may also be contributing to the erosion, the sea-level fluctuation shown in the video is the result of tides and wind—not a global phenomenon, Jones added.
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