Skip to main content
U.S. flag

An official website of the United States government

Warming air and sea temperatures in the Arctic are leading to longer periods of permafrost thaw and ice-free conditions during the summer months, which can weaken the coastal bluffs and increase their vulnerability to storm surge and wave impacts.

Map of an island with labels to show the study area and other locations.
Large map shows Barter Island on Alaska’s North Slope. LRRS, Long Range Radar Site.

In September 2015, scientists from the U.S. Geological Survey (USGS) and the University of California, Santa Cruz (UCSC) surveyed rapidly eroding permafrost bluffs on Barter Island, a remnant of low-elevation tundra on Alaska’s Arctic coast. Warming air and sea temperatures in the Arctic are leading to longer periods of permafrost thaw and ice-free conditions during the summer months, which can weaken the coastal bluffs and increase their vulnerability to storm surge and wave impacts. The 2015 survey is part of a long-term effort to document seasonal to decadal coastal-bluff change on the island’s north coast.

View from the sky of a coastline, the photo has been labeled to show features.
Close-up map shows study sites on the coastal bluffs.

In spite of bleak weather conditions that thwarted scheduled flights to Barter Island for many days, the survey team achieved its goals on the island. The researchers drilled into the permafrost to obtain samples of permafrost ice, pore water, and sediment. They are using geochemical techniques, such as measurement of radon and stable isotopes, to trace the movement of groundwater and examine its effects on sediment erosion. Several geophysical techniques were used to image the subsurface structure of permafrost features, such as ice-wedge polygons, and to measure the salt content and internal structure of materials that make up the frozen ground. 

Two plots from different months show ground temperature versus depth using color gradients.
Repeat electrical resistivity tomogram (ERT) images collected on the coastal bluffs of Barter Island reveal the effects of one summer thaw cycle. Hotter colors indicate high resistivity values, which in this case likely represent low-conductivity permafrost. ERT profiles were collected along the same transects during the 2015 fieldwork to examine annual change and to identify sites for drilling into permafrost.

Repeat electrical resistivity tomograms (ERTs) had been collected on the coastal bluffs in Barter Island in early and late summer 2014 to evaluate the effects of one summer’s thaw cycle. ERTs provide a cross-sectional view of electrical resistivity within the bluffs. Because ice is a poor conductor of electricity and thus has high resistivity, ERTs reveal the distribution of subsurface permafrost. ERTs were collected from the same bluffs during the 2015 survey to examine annual change and to identify sites for drilling into the permafrost.

To complement these geo-electrical methods, the September 2015 survey team collected data with a phase-sensitive radio echo sounder (pRES). Whereas traditional echo sounders send sound waves through water to detect boundaries between materials with differing physical properties, the pRES sends radio waves through ice. pRES data can be used to image the base of an ice mass and also internal reflecting layers, such as layers of liquid water or variations in the size of air bubbles in the ice. The USGS researchers were particularly interested in another strong radio-wave reflector: the interface between freshwater and saltwater. They collected pRES data along select survey lines for comparison with the ERTs to determine where the subsurface gets salty and so document the influence of seawater in permafrost.

An icy bluff covered with a thick layer of soil and grass chunks off onto the beach below.
Photograph of an eroding coastal bluff on Barter Island on the northern coast of Alaska.

A primary focus of the 2015 effort was to ground truth the remote-sensing methods by collecting permafrost samples. A custom-designed drilling platform allowed the team to obtain samples from depths down to approximately 6 meters in permafrost. Preliminary results confirm that the permafrost pore-water salinities near the bottom of the cores exceeded seawater values, an observation supported by the 2014 and 2015 ERT images. The pore-water samples from these drill holes are being used for additional geochemical analyses to illuminate the oceanic and geologic evolution of this dynamic coastal environment.

The researchers aim to document seasonal to decadal coastal-bluff change and associated hydro-geologic processes along a 3-kilometer stretch of coast on Barter Island by using the techniques outlined above along with recently collected time-lapse photography; historical maps and imagery; GPS surveys of the beach and nearshore; sediment sampling and analysis; 3-D models of the terrain derived from aerial photography and airborne lidar (a laser-based surveying technique); photographs of the bluffs taken from an all-terrain vehicle (ATV); measurement of water levels, currents, and salinity in lagoons and nearshore waters; and numerical models of waves, storm surge, and inundation.

Below are photographs from a mounted time-lapse camera looking eastward along Barter Island’s north shore document how the coastal bluffs and beach changed during a single summer. View the complete time-lapse sequence in this cool video (runtime: 2 minutes, 26 seconds).


Photo from a time-lapse camera looking eastward along the north shore of Barter Island, Alaska, on June 15, 2014
A, Sea ice and frozen shoreline (June 15, 2014)
View looks along an ice-rich permafrost bluff that is eroding muddy chunks of tundra onto a sandy beach.
B, Ice-free and wide beach; dark-colored material on beach is fine-grained sediment eroded from bluffs (July 10, 2014).


View along a grassy coastal bluff that is slumping into the ocean.
C, Summer storm from the west eroding the beach (July 25, 2014).
View along a snowy, grassy coastal bluff that is slumping into the ocean, waves are right at the bottom of cliff.
D, Late-summer extreme storm with waves crashing into the bluff (September 3, 2014).



The Barter Island study is part of a larger investigation of climate-change impacts on Alaska’s Arctic coast. See website, “Climate Change Impacts to the U.S. Pacific and Arctic Coasts: Research” and related Sound Waves article, “Northern Alaska Coastal Erosion Threatens Habitat and Infrastructure.”

Two photos, one shows a man using a hand-held drilling core, the other shows the core of dirt pulled out.
Left, Cordell Johnson drilling and coring the interior of the bluff to ground-truth geophysical methods. Right, a core section filled mostly with ice.

Scientists who contributed to the September 2015 survey included Peter Swarzenski, Bruce Richmond, Cordell Johnson, Tom Lorenson, Li Erikson, and contractor Amy West from the USGS Pacific Coastal and Marine Science Center, and Neil Foley and Slawek Tulaczyk from UCSC. The work falls under USGS projects on coastal aquifers and coastal climate impacts.

Essential support for this field effort was provided by aquatic biologist Greta Burkart and Arctic National Wildlife Refuge (ANWR) Manager Brian Glaspell, both of the U.S. Fish and Wildlife Service (USFWS). On the last day of fieldwork, Bruce Richmond was asked to give a briefing to USFWS Director Daniel Ashe, Senator Tim Kaine (D, Virginia), Senator Martin Heinrich (D, New Mexico), Deputy Regional Director of Alaska Region USFWS Karen Clark, and Brian Glaspell.

Get Our News

These items are in the RSS feed format (Really Simple Syndication) based on categories such as topics, locations, and more. You can install and RSS reader browser extension, software, or use a third-party service to receive immediate news updates depending on the feed that you have added. If you click the feed links below, they may look strange because they are simply XML code. An RSS reader can easily read this code and push out a notification to you when something new is posted to our site.