Glaciers play an important role in Southeast Alaska watersheds. They act as frozen freshwater reservoirs throughout the year, while cold, sediment-heavy glacial runoff has a unique signature that affects environmental signals that define where salmon choose to spawn and the delivery of nutrients to coastal estuaries. Yet, peak glacial melt is arriving earlier each season than in previous decades, altering stream habitat and hydrologic patterns in the surrounding watersheds and downstream estuaries. 

Alaska CASC postdoctoral fellow Joanna Young recently led a team of scientists in studying glaciers’ contribution to coastal rivers by developing a model that combines glacial, riverine and soil moisture processes to identify if increases in water volume are driven by snowmelt, heavy precipitation, or glacial runoff. 

Their findings, published in the journal Water Resources Research, indicate that annual glacier ice melt on the Juneau Icefield has increased by 10% per decade since the 1980s, and glacier runoff by 3%. Additionally, peak runoff from glacial melt every year is occurring 2.5 days earlier each decade now than in the 1980s. 

“Our findings from the Juneau Icefield show that glacier loss is impacting streamflow regimes in coastal watersheds along the Gulf of Alaska, with implications for freshwater salmon habitat and the function of coastal marine ecosystems that receive runoff from glaciers,” said co-author Eran Hood, professor of environmental science at the University of Alaska Southeast.

Increasing glacial melt can exacerbate flood risk, have negative implications for freshwater salmon habitat, and alter the function of coastal marine ecosystems in the Gulf of Alaska. Understanding future changes to streamflow patterns may inform infrastructure planning and resource management in the Gulf of Alaska.

Lead author Joanna Young is an Alaska CASC postdoctoral fellow working with Dr. Eran Hood, professor of environmental science at University of Alaska Southeast.