Alaska glacier outbursts causing widespread floods in Juneau

Alaska is facing severe flooding as “unprecedented” glacial lake outburst flood, causing damage to more than 100 homes.

The glacier flood from the Suicide Basin swelled the Mendenhall River to record levels, causing destructive flooding in Juneau on Tuesday, nearly one year after the same river flooded on Aug. 7, 2023.

In Alaska, residents are evacuating as floodwaters from a glacial lake threaten communities near the state capital, Juneau. Meltwater from a basin dammed by the Mendenhall Glacier has begun to escape, prompting fears of record-breaking flooding.

The National Weather Service in Juneau has issued a flood warning, with the Mendenhall River rising rapidly and posing a serious threat to nearby homes.

After several days of alerts, officials confirmed that water had begun breaching the natural ice dam. By yesterday morning, river levels had surged above 16 feet, well beyond the 14-foot major flood threshold.

The met department warned that this will be a new record based on all available data. Located about 19 kilometers from Juneau, the Mendenhall Glacier is a popular tourist attraction and has been a source of recurring flood threats since 2011.

Glacial lake outburst floods, occur when meltwater trapped behind natural ice or rock barriers suddenly drains, comparable to pulling the plug from a full bathtub.

On Sunday, Alaska Governor Mike Dunleavy declared a state disaster in response to the “imminent threat” posed by the floodwaters.

Last year, similar flooding damaged hundreds of homes in the region. Scientists warn that as global temperatures rise, mountain glaciers are retreating, creating more glacial lakes that are larger and increasingly unstable.

Experts caution that while the exact timing of such floods is difficult to predict, climate change is expected to increase both the frequency and severity of glacial outburst events in the years ahead.