Glacial outburst floods aren't a new phenomenon in Alaska, but climate change is scrambling the geography of risk.

Sections of Alaska’s capital city are bracing for the arrival of what could be record floodwaters due to rainwater and snowmelt flowing downstream from a basin dammed by the Mendenhall Glacier.

A water basin in Alaska is overflowing its ice dam, the Mendenhall Glacier, and flooding the state capital, Juneau. Experts expect the likely record-breaking event to peak today, and officials have asked residents in parts of the city and borough to evacuate.