Bursting ice dam in Alaska highlights risks of glacial flooding around the globe

by Michael Nguyen
Glacial Flooding

The collapse of a gray, two-story house with white trim and its subsequent descent into the river below, accompanied by a floating piece of its roof, highlighted the aftermath of a ruptured glacial dam in Alaska’s capital. The torrential waters also caused a neighboring condo building to perch precariously on the brink, as erosion had already eroded its foundation. This calamity occurred over the weekend due to the bursting of a glacial dam, known as a jökuhlaup, which is a relatively unfamiliar phenomenon in the United States. However, researchers underscore the global risk posed by such glacial floods, potentially endangering around 15 million individuals worldwide.

Amanda Arra, whose house was left dangling perilously over the river bank, recounted how she watched trees tumble into the water, fueling her unease as the destructive scene unfolded. The flood event in Juneau originated from a lateral basin of the impressive Mendenhall Glacier, which serves as a barrier for rain and snowmelt that accumulates in the basin during the warmer seasons. Ultimately, the water surged from beneath the glacier and flowed through Mendenhall Lake, continuing its course down the Mendenhall River.

Although water releases from the basin have sporadically led to flooding since 2011, they typically occur more gradually over several days, as explained by Eran Hood, an environmental science professor at the University of Alaska Southeast. The uniqueness of Saturday’s incident lay in the rapidity of the water surge, causing the river’s flow to increase to approximately 1.5 times the previous highest recorded level. This deluge was so forceful that it swept away research sensors meant to study the glacial outburst phenomenon.

The aftermath of the event resulted in the complete loss of two homes and partial damage to a third, according to Robert Barr, Juneau’s deputy city manager. Fortunately, there were no reported casualties. Eight buildings, including those that succumbed to the water’s force, were declared uninhabitable, though some might be salvageable with significant repairs or bank stabilization efforts. Others suffered lesser degrees of harm.

While global climate change contributes to the melting of glaciers such as the Mendenhall, its relationship to these types of floods is intricate and multifaceted. The basin where rain and meltwater gather was previously covered by the Suicide Glacier, which used to flow into the Mendenhall Glacier, providing it with ice. However, as the climate has warmed, the Suicide Glacier has retreated, leaving a lake in the basin blocked by the Mendenhall.

The connection between climate change and the overarching phenomenon is evident, but the erratic ways in which these waters breach ice dams and trigger downstream floods are not entirely attributable to climate change. Researchers highlight that while climate change is a causal factor in the overall phenomenon, it does not directly induce each individual flood event.

The unpredictability in terms of timing and water volume in these flood events presents challenges in preparation, according to Celeste Labedz, an environmental seismologist at the University of Calgary. More than half of the people at risk from glacial outburst floods are concentrated in four countries: India, Pakistan, Peru, and China, as indicated by a study published in Nature Communications in the present year.

Though glacial outburst floods are linked to climate change, the distinctive ways in which they unfold and their subsequent impact are shaped by complex factors. The vulnerability of the ground along the Mendenhall River, composed primarily of loose glacial deposits, makes it particularly susceptible to erosion. Had the flood coincided with heavy rainfall, the damage could have been even more extensive. Residents like Chris and Bob Winter, whose house flooded for the first time in 2014 and again during the recent event, are grappling with significant losses and uncertainty about the future. The occurrence emphasizes the critical need for understanding and managing the consequences of glacial melt and the potential for subsequent floods on a global scale.

Frequently Asked Questions (FAQs) about Glacial Flooding

What caused the flooding in Alaska’s capital?

The flooding in Alaska’s capital, Juneau, was caused by the bursting of a glacial dam, known as a jökuhlaup. This glacial dam, formed by the Mendenhall Glacier, usually holds rainwater and melted snow in a basin. However, due to its bursting, a rapid surge of water flowed into the Mendenhall River, causing significant flooding.

How does glacial melting relate to these floods?

While climate change is causing the melting of glaciers, like the Mendenhall Glacier, the direct link between glacial melting and the specific floods caused by glacial dam bursts is complex. The melting contributes to the overall phenomenon, but the erratic and rapid nature of these floods is influenced by various factors beyond just glacial melting.

How did the burst glacial dam impact homes and structures?

The burst glacial dam led to the destruction of multiple buildings, including complete loss of some homes and partial damage to others. The floodwaters swept away houses and caused severe erosion, undermining foundations and destabilizing structures along the riverbank.

How many people are at risk from glacial floods globally?

Around 15 million people worldwide are at risk from glacial floods. These events, known as glacial outburst floods or jökuhlaups, can occur when glacial dams rupture, sending a sudden surge of water downstream, potentially leading to significant damage and loss of life.

Are these glacial flood events increasing due to climate change?

While the phenomenon of glacial outburst floods is influenced by climate change-induced glacial melting, the variability in their occurrence makes it difficult to determine a direct increase solely due to climate change. Climate change contributes to the conditions that can lead to these floods, but other factors also play a role in their occurrence.

More about Glacial Flooding

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Mike August 8, 2023 - 9:48 am

alaska’s natural beauty’s gettin’ trashed by these floods. and it’s not just local, millions worldwide at risk? wild, man.

Alex August 8, 2023 - 1:58 pm

whoa, alaska’s glacial floods sound mega scary! those dams bursting and flooding homes, that’s real bad. climate change’s messin’ things up big time.

Jessie August 8, 2023 - 4:14 pm

omg, like, glacial floods? seriously?! didn’t even know that was a thing. these floods, they’re like a silent risk hanging over us, huh?

Chris August 8, 2023 - 5:07 pm

those poor folks in alaska, losing homes to floods. but like, can’t believe climate change makes the glacier’s melt and floods happen. crazy world.

Sarah August 9, 2023 - 6:44 am

houses crumbling into rivers? that’s like a movie scene, but it’s for real. and these glacial floods aren’t gonna stop, right? scary stuff.


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