Alaska Mountain Glaciers Raise Global Sea Level

Posted by on Jul 22, 2015

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Alaska’s impact on global sea level rise is becoming more pronounced. Its melting glaciers, particularly the minority mountain glaciers, will be a major driver of sea level change in the coming decades, according to a new study conducted by Chris Larsen, research associate professor at the University of Alaska Fairbanks, and his colleagues.

The glacier world in Alaska. Photo credit: Stephen Kennedy (via Flickr).

The glacier world in Alaska. Photo credit: Stephen Kennedy (via Flickr).

With over 100,000 glaciers, Alaska is home to half of the world’s glaciers. Every seven years, glacier loss from Alaska contributes a 1-foot thick layer of water covering the state of Alaska. Though mountain glaciers hold less than 1% of the total glacier volume on the Earth, the recession of mountain glaciers contribute to nearly 1/3 of current sea level rise.

Larsen and his team examined 116 glaciers across Alaska to estimate ice loss from melting and iceberg calving between 1994 to 2013. Iceberg calving, the unique process of ice chunks breaking off at the edge of a glacier, is underlined in the study because few existing observations or models value the impact of iceberg calving under climate change.

“We’ve long wondered what the contribution of iceberg calving could be across the entire state,” O’Neel, one of the researches, told the American Geophysical Union.  The Columbia Glacier in Prince William Sound has retreated more than 12 miles mostly due to iceberg calving since 1980.

The University of Alaska Fairbanks collected airborne lidar altimetry data, highly specialized research aircrafts, as part of NASA’s Operation IceBridge mission since 2009. The mission aims to picture the Earth’s polar ice in unprecedented detail with innovative science instruments to better connect the polar regions with the global climate system.

NASA's Operation IceBridge Survey Flight Over Saunders Island and Wolstenholme Fjord. Source: NASA Goddard Space Flight Center (via Flickr).

NASA’s Operation IceBridge Survey Flight Over Saunders Island and Wolstenholme Fjord. Source: NASA Goddard Space Flight Center (via Flickr).

The team also integrated the new data with information from the 1990s collected by the University scientists and Keith Echelmeyer, a pilot, mountaineer and pioneer glaciologist. They developed a more detailed characterization of the size and shape of every glacier in Alaska, in addition to the glaciers of southwest Yukon Territory and coastal northern British Columbia.

With the new data inventory, the research team has made some significant discoveries. Across the years from 1994 to 2013, Alaska’s tidewater glaciers contributed to only 6% of Alaska’s mass loss. Glaciers that end in the ocean, called tidewater glaciers, make minimal contribution to sea level rise, while glaciers ending on land are primary contributors to mountain glacier mass loss driven by climate change.

“This work has important implications for global sea level projections. With improved understanding of the processes responsible for Alaska glacier changes, models of the future response of these glaciers to climate can be improved,” Larsen told the American Geophysical Union. Despite the fact that the impact of the large-scale tidewater glacier losses in Alaska is negligible, Alaska will remain a major contributor to global sea level rise through its mountain glaciers.

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