The Beaufort Sea coast along the northern edge of Alaska is a place of extremes. Home to the northernmost year-round settlements in the United States, this region sees round-the-clock daylight during the three-month Arctic summer and is shrouded in darkness and ice the rest of the year.
Seven Decades of Coastal Change at Barter Island, AK
Published in journal “Remote Sensing”
As climate change brings sea-level rise, warmer water and air temperatures, and powerful storms to coastal areas across the country, it is Alaska’s Arctic coast that may see the most extreme effects.
A recently published study from researchers at the USGS Pacific Coastal and Marine Science Center and collaborators takes a comprehensive look at the rates, patterns, and drivers of coastal change at Barter Island, Alaska, on the Beaufort Sea coast. This community of less than 300 people is located along the northern boundary of Arctic National Wildlife Refuge.
Analyzing a combination of historical maps, aerial photography, declassified satellite photography, and high-resolution satellite imagery that date back more than 70 years, researchers found that rapid change is occurring along shorelines and coastal bluffs at Barter Island.
Between 1950 and 2020, the bluffs along the open-ocean coast of Barter Island retreated up to 163 meters (535 feet), more than the length of one and a half football fields. During some years (2013, for example), the bluffs retreated as much as 21 meters in a single year. Over the 70 years of measurement, the rate of retreat increased steadily, with consistently high rates (more than two meters a year) since 2015. Most of this change has historically occurred during the approximately three months of ice-free conditions each year.
“The extensive archive of image data from the Barter Island region, which is rare along Arctic coasts, provides a detailed picture of how the coastline has changed through time and is a step toward identifying the relative importance of the different physical drivers of permafrost coastal erosion,” said USGS Geologist Ann Gibbs, lead author of the study. “Because the seasonal ice wreaks havoc on any permanent instrumentation along the Alaska coast, there are few wave buoys or other in situ devices that can make oceanographic measurements. This study uses global-scale reanalysis products downscaled to the Beaufort Sea coast, to model past conditions of wave energy and air and water temperature to understand the physics of what's driving the observed changes.”
In addition to the rapid retreat of coastal bluffs at Barter Island, the study found that surface waters are warming, wave action is increasing, and the number of sea-ice-free days has more than tripled since 1979, from 40 days to 140. Wave energy was found to be the dominant physical driver of bluff retreat, followed by elevated sea-surface and air temperatures.
“The goal is to make projections on what the future flooding and erosion hazard might be,” said Research Oceanographer Li Erikson, a co-lead of the study. “To get there, we need to identify and understand the main physical forcing mechanisms and drivers. By looking to the past and understanding the processes involved, we can apply projected climate-change conditions and estimate future scenarios and hazards.”