Alaska's melting glaciers remain one of the largest contributors to the world's rising sea levels, two University of Alaska Fairbanks geophysicists write in a report published this month in Science magazine.
Anthony Arendt and Regine Hock joined 14 scientists from 10 countries who combined data from field measurements and satellites to get a global picture to date of glacier mass losses and their contribution to rising sea levels.
"In general, increased runoff from glaciers causes a reduction in the salinity of the upper layers of the ocean," Arendt wrote, in an email responding to questions about the study. "This salinity change causes an acceleration of the flow of water along the Gulf of Alaska (the Alaska Coastal current).
"This current transports heat from the North Pacific into the Gulf of Alaska (from southeast to northwest). Therefore, an acceleration of this flow results in an overall increase in ocean temperatures. Although there are few measurements of this, an Alaska station near Seward indicates that such changes (decreasing salinity and increasing ocean temperature) have been occurring from 1970 to the present," Arendt said.
"These changes in salinity, temperature and acidification have important implications for the aquatic ecosystems of the Gulf of Alaska. For example, the timing and magnitude of primary productivity and salmon productivity depend on these ocean conditions," Arendt said. "In addition to these large scale effects, there are several ongoing studies showing that fjord areas like Prince William Sound and Glacier Bay are particularly sensitive to change in ocean temperature and salinity. In these more sheltered waters, ecosystem health is more directly tied to freshwater discharge."
The study was compiled in order to provide new estimates to the Intergovernmental Panel on Climate Change, which compiles a global report every six years summarizing scientists' best estimates of the environmental impacts of climate variation.
Arendt and Hock helped compile a global inventory of the Earth's glaciers, with a focus on Alaska's glaciers. Before the study, only about 40 percent of Alaska's glaciers were inventoried.
Hock said more field data is needed to supplement satellite observations for a better understanding of how glaciers in Alaska will respond to future climate variations.