After a glacial dam outburst destroyed homes in Alaska, a look at the risks of melting ice masses

Aug 8, 2023, 4:25 PM

People pause on a bridge over the swollen Mendenhall River in Juneau, Alaska, on Sunday, Aug. 6, 20...

People pause on a bridge over the swollen Mendenhall River in Juneau, Alaska, on Sunday, Aug. 6, 2023, for a closer look or photos after a glacial dam burst earlier in the weekend caused flooding along the river and Mendenhall Lake. The city said at least two buildings were destroyed. (AP Photo/Becky Bohrer)

(AP Photo/Becky Bohrer)

JUNEAU, Alaska (AP) — People in Alaska’s capital have lived for more than a decade with periodic glacial dam outbursts like the one that destroyed at least two homes over the weekend.

But the most recent flood was surprising for how quickly the water moved as the surging Mendenhall River devoured riverbanks, undermining and damaging homes, and prompted some residents to flee.

Here are some issues surrounding glaciers and the floods that result from the bursting of snow-and-ice dams.


The water came from a side basin of the spectacular but receding Mendenhall Glacier that is known as the Suicide Basin. The glacier acts as a dam for precipitation and melt from the nearby Suicide Glacier that collects in the basin during the spring and summer. Eventually the water gushes out from under the Mendenhall Glacier and into Mendenhall Lake, from which it flows down the Mendenhall River.

Such glacial dam outbursts have been occurring in the area since 2011, but often the water releases more slowly, typically over a few days, said Eran Hood, a University of Alaska Southeast professor of environmental science.

Lake and streamflow levels reached record highs during Saturday’s flooding in Juneau, which is home to about 30,000 people and has numerous homes and popular hiking trails near the meandering Mendenhall River.


Climate change is melting glaciers. A study released this year suggested significant melting by the end of this century amid current climate change trends, and a separate report indicated that glaciers in parts of the Himalayas are melting at unprecedented rates.

But the relationship between the changing climate and glacial outburst floods like the one in Juneau is complicated, scientists say.

The basin where the rain and meltwater collect was formerly covered by Suicide Glacier, which used to contribute ice to the Mendenhall Glacier. Smaller glaciers, like Suicide Glacier, respond more rapidly to changes in climate and the retreat of Suicide Glacier exposed the basin, Hood said.

But the floods that occur “really have nothing to do with climate change and glacier melt directly,” he said.

“The phenomenon itself is caused by climate, but the individual floods don’t have anything to do with climate because they’re basically just the case where water is filling up a basin and then draining at some point during the summer,” he said.


These events aren’t new and happen in places around the world, threatening about 15 million people globally, according to researchers. There’s an Icelandic term for them, jökuhlaups.

But they’re not something many in the U.S. think about — even in Alaska, which is home to the bulk of U.S. glaciers, many of them remote.

One challenge with glacial dam outbursts is that the severity and timing can vary from year to year, researchers said.

Celeste Labedz, an environmental seismologist at the University of Calgary, said glaciers are dynamic. For example, as the long-retreating Mendenhall Glacier continues to melt, a process aided by the warming climate, it’s possible it will someday no longer block the basin and flooding from that basin will no longer be a concern. But there’s also potential for new basins to form, she said.

“As a glacier is thinning and retreating and changing, you can see some floods are going to stop happening and new ones are going to start happening. It’s a variable system,” Labedz said.


In addition to flooding risks, glacial loss can mean diminished water supplies in parts of the world and could affect such things as agriculture and tourism.

Alaska is a bucket-list destination for visitors drawn by wild landscapes such as mountains and craggy glaciers that spectacularly calve into lakes or the ocean.

Glaciers cover about 33,000 square miles (85,000 square kilometers) of the state, and annual ice loss from glaciers in Alaska would be enough to cover Texas in 4 inches (10 centimeters) of water, said Christian Zimmerman, director of the U.S. Geological Survey’s Alaska Science Center.

Retreat of glaciers can also affect ecosystems, including salmon habitat, something researchers are hoping to better understand.

United States News

Associated Press

Surgeons perform second pig heart transplant, trying to save a dying man

WASHINGTON (AP) — Surgeons have transplanted a pig’s heart into a dying man in a bid to prolong his life – only the second patient to ever undergo such an experimental feat. Two days later, the man was cracking jokes and able to sit in a chair, Maryland doctors said Friday. The 58-year-old Navy veteran […]

1 hour ago

Associated Press

GOP candidate challenging election loss in race to lead Texas’ most populous county drops lawsuit

HOUSTON (AP) — The highest profile Republican candidate who had sued seeking to overturn election results in the nation’s third-most populous county, a Democratic stronghold in deeply red Texas, has dropped her lawsuit. Alexandra del Moral Mealer was one of 21 GOP candidates who had filed lawsuits challenging their losses in November’s election in Harris […]

2 hours ago

Associated Press

Convicted sex offender back in custody after walking away from a St. Louis hospital

SHREWSBURY, Mo. (AP) — A man convicted of child sex crimes is back in custody after walking away from a St. Louis hospital, authorities said. Tommy Wayne Boyd, 45, was transported Wednesday from the Potosi Correctional Facility to Mercy Hospital South for medical treatment. Surveillance video later showed him walking away from the hospital, St. […]

2 hours ago

Associated Press

Lawmakers author proposal to try to cut food waste in half by 2030

PORTLAND, Maine (AP) — A bipartisan coalition of U.S. lawmakers has introduced a proposal designed to cut food waste in half by 2030. The lawmakers submitted their legislation on Thursday and said it would improve collaboration between the U.S. Department of Agriculture and regional waste prevention and food recovery organizations. The lawmakers said the proposal […]

3 hours ago

Associated Press

Chicago man gets life in prison for role in 2016 home invasion that killed 5 people

CHICAGO (AP) — A Chicago man convicted of fatally shooting five people during a 2016 home invasion has been sentenced to life in prison. A Cook County judge on Thursday sentenced Lionel Parks, 35, who was convicted in July in the December 2016 killings at a drug dealer’s home on the city’s South Side, the […]

4 hours ago

Arizona Reps. Andy Biggs, left, and Eli Crane are seen together in a file photo. They were among fi...

Alexandria Cullen and Adrienne Washington/Cronkite News

Arizona Reps. Biggs, Crane vote to block defense bill as shutdown looms

Two Arizona lawmakers were among five GOP House members who broke ranks Thursday and voted to block the defense authorization bill.

5 hours ago

Sponsored Articles

Home moving relocation in Arizona 2023...

BMS Moving

Tips for making your move in Arizona easier

If you're moving to a new home in Arizona, use this to-do list to alleviate some stress and ensure a smoother transition to your new home.


Ignite Digital

How to unlock the power of digital marketing for Phoenix businesses

All businesses around the Valley hopes to maximize their ROI with current customers and secure a greater market share in the digital sphere.


Mayo Clinic

Game on! Expert sports physicals focused on you

With tryouts quickly approaching, now is the time for parents to schedule physicals for their student-athlete. The Arizona Interscholastic Association requires that all student-athletes must have a physical exam completed before participating in team practices or competition.

After a glacial dam outburst destroyed homes in Alaska, a look at the risks of melting ice masses