Alaskan Glaciers on the Brink

A recent study published in Nature Communications has revealed that the Juneau Icefield, which extends across Alaska and British Columbia, is undergoing rapid glacial retreat.

Glacial Retreat:

Glacial retreat refers to the shrinking or receding of a glacier over time. This occurs when ice melts or sublimates faster than new snow or ice accumulates.

• Between 2015 and 2019, glacier shrinkage was five times faster than in the mid-20th century.
• Alaskan icefields are responsible for 25% of global glacier ice loss and significantly contribute to global sea level rise. At the current rate, all Alaskan ice could vanish within 250 years.

Cause of Acceleration:

• The rapid ice loss coincides with a 1.39°C temperature increase at Juneau Airport from 1941 to 2020.
• Researchers attribute this temperature rise to a shift in the Pacific Decadal Oscillation (PDO), a long-term fluctuation in Pacific Ocean temperatures that switched to a warm phase around 1976. This shift led to increased precipitation and warmer temperatures in Alaska and Juneau, accelerating glacier melt.
• A significant factor in this acceleration is the rising Equilibrium Line Altitude (ELA), the zone where snowfall and melting balance each other throughout the year.
• As the ELA rises, a larger surface area is exposed to melting, which intensifies ice loss across the entire icefield.