The recent flooding in Juneau, Alaska was caused by a smaller glacier near Mendenhall Glacier retreating due to climate change, leaving a basin that fills with rainwater and snowmelt each spring and summer. This water creates pressure that forces its way under or around the ice dam created by Mendenhall Glacier, flooding streets, homes, and the river. This week’s flooding was unprecedented and left residents shaken as they cleaned up afterwards. Climate change plays a minimal role in the year-to-year variations in the flooding, according to environmental science professor Eran Hood. Eventually, Mendenhall Glacier will thin enough that it can no longer act as a dam, leading to more flooding events in the future.
The flooding in Juneau is a reminder of the global risk from bursting snow-and-ice dams, which could threaten about 15 million people worldwide. Juneau, a city of about 30,000 people, is already struggling with a housing shortage and limited rental car agencies to accommodate flood victims. The Mendenhall River crested at a new record level, reaching farther into the Mendenhall Valley and impacting some homes outside expected flood zones. Residents had to evacuate to shelters, with one resident recalling how she had to move her cars to higher ground due to rising water levels.
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