US state of Alaska bracing for potential record glacier-related flooding

HOUSTON, United States

The US state of Alaska is bracing for potential record glacier-related flooding, and residents of the capital Juneau are on notice to evacuate, according to Wednesday media reports.

Emergency officials warned that massive floodwaters could deluge sections of Juneau from the culmination of snowmelt and rainwater flowing downstream from a basin dammed by the Mendenhall Glacier about 12 miles (19.3 kilometers) away.

Some of the city's 30,000 residents who live in the flood-prone area have already evacuated their homes and officials are warning people not to take any chances.

"Don't wait, Evacuate," said a warning sent out to residents.

Authorities said water had already started escaping the ice dam as of Tuesday and they expected heavy flooding on Wednesday.

"This will be a new record, based on all of the information that we have," National Weather Service meteorologist Nicole Ferrin told a news conference.

Officials said previous flooding events over the past 14 years have swept away houses and flooded hundreds of homes.

The government set up temporary barriers this year in hopes of protecting homes in the flood zone.

Scientists said the flooding is happening because a smaller glacier near Mendenhall Glacier retreated — which they say is a casualty of global warming — and left a basin, known as Suicide Basin, that fills with rainwater and snowmelt each spring and summer.

When the water creates enough pressure, it forces its way under or around the ice dam created by the Mendenhall Glacier, enters Mendenhall Lake, and eventually flows down the Mendenhall River.

Juneau saw successive years of record floods in 2023 and 2024, with the river last August cresting at 15.99 ft (4.87 m).

This year's flooding is predicted to crest between 16.3 and 16.8 ft (4.97 and 5.12 m), according to the National Weather Service.