The Gulf of Alaska is like a giant drain. Each year a massive amount of freshwater—equal to nearly twice the annual discharge of the Mississippi River—enters this body of water. This freshwater runoff is economically and ecologically important, but a new study shows that as glaciers change, future runoff patterns from may have important regional differences. Researchers from USGS, University of Alaska Fairbanks, and University of Alaska Southeast based the study on some of the longest paired glacier change and runoff records in Alaska. Interior Alaska's Gulkana Glacier and Kenai's Wolverine Glacier have been tracked by USGS for over 45 years. Researchers compared the glaciers' mass balance data—the budget of ice gained versus ice lost each year—to measurements of streamflow from the same basins.
They found that between 1967-2011 both glaciers had lost mass. What surprised them, however, was the proportion of streamflow that came directly from the shrinking glaciers. In the Alaska Range, glacier runoff made significant and increasing contributions to the total runoff. On the coast, where there is significantly more precipitation in general, the loss of glacier ice did not substantially affect the volume of streamflow. In the future, runoff volumes from interior Alaska glaciers are likely to be altered much more strongly by climate change compared to glaciers located in coastal, maritime environments.
This study is important for several reasons. Glacier runoff is different from rain or snow runoff—it has minerals and organic material that support species at the bottom of river and ocean food chains. Glacier runoff is also very cold, so it affects salmon habitat and the movement of ocean currents. Moreover, glacier runoff provides a notable water and power resource. Runoff from the Eklutna Glacier is used to quench the thirst and power needs of Anchorage residents.
This research will help project future changes in runoff that could impact habitat quality, freshwater availability, and hydropower development.
The work was supported by the Alaska Climate Science Center (AK CSC) under the project "Assessing the Sensitivity of Alaska's Coastal Rainforest Ecosystem to Changes in Glacier Runoff". Established in 2011, the AK CSC is one of eight regional centers across the US that brings together university and agency researchers to meet climate change research needs in Alaska.
The full article, “Assessing streamflow sensitivity to variations in glacier mass balance” is available online: http://link.springer.com/article/10.1007/s10584-013-1042-7/fulltext.html