The glacial flooding that sent residents of Alaska’s capital city scrambling this week has become an annual ordeal for those who live along the picturesque river that winds from the nearby Mendenhall Glacier.
This year, a giant wall of reinforced sandbags erected with the help of the U.S. Army Corps of Engineers held back the worst of the flooding in Juneau, to residents’ great relief. The damage was nothing like what happened the last two years, when flooding was rampant and some homes washed away.
But the wall is merely a temporary barrier. The effort to devise a permanent solution is complicated by what scientists don’t yet know about how human-caused global warming will impact the yearly outbursts of water from an ice dam at the glacier. Juneau is just one of many communities around the globe struggling to engineer a way out of the worst damage from climate change.
“We can’t keep doing this,” said Ann Wilkinson Lind, who lives on the banks of the Mendenhall River. “We need a levee or some other permanent fix. … This is an emergency situation that can’t take 10 years for this study and that study and every other study. It needs to be done now.”
The Mendenhall Glacier is about 12 miles (19 kilometers) from Juneau, home to 30,000 people in southeast Alaska, and is a popular tourist attraction due to its proximity and easy access on walking trails. Homes on the city’s outskirts are within miles of Mendenhall Lake, which sits below the glacier, and many front the Mendenhall River.
The glacial outburst flooding from the Mendenhall is itself a phenomenon caused by climate change, which is thinning glaciers around the world. A glacier nearby retreated, leaving behind a large bowl — Suicide Basin — that fills each spring and summer with rainwater and snowmelt dammed by the Mendenhall.
When that water builds up enough pressure, it forces its way under or around the ice dam, enters Mendenhall Lake, and flows down the Mendenhall River toward Juneau. Flooding from the basin has been an annual concern since 2011 and has gotten worse, with new water-level records being set each of the last three years.