Scientists have, for the first time, observed the unleashing of an enormous glacial lake flooding event in East Greenland. The rare outburst involved 3,000-plus billion liters of meltwater bursting forth in a matter of weeks.

Witnessed by researchers from the University of Copenhagen, the natural phenomenon provides insight into the powerful and potentially dangerous forces that can be released by meltwater, a press release from University of Copenhagen’s Niels Bohr Institute said.

“Imagine an enormous bathtub atop a mountain filled with water equivalent to three times Denmark’s annual water consumption, and then suddenly bursting. This is essentially what happened when the massive Catalina Lake in East Greenland released 3.4 cubic kilometers of meltwater — 3,000 billion liters — into the Scoresby Sound fjord,” the press release said.

The enormous volume of water released by the lake made it one of the three largest events of its kind ever to be documented.

The meltwater outburst flood happened from September 23 to October 11, during which time the water level of Catalina Lake fell by 154 meters. The scientists were able to use satellite imagery to observe the spectacle in real time.

Satellite image of Catalina Lake in an undated photo. University of Copenhagen

“We have previously found traces of similar outburst floods, but due to polar night and clouds obstructing the potential for satellite observations, this is the first time that researchers have been able to monitor an event and measure the water volumes in real time,” explained Aslak Grinsted, a climate researcher with the Niels Bohr Institute, in the press release.

The outburst flood was caused by the accumulation of meltwater from Catalina Lake over the last two decades. The lake sits nestled in a valley obstructed by the Edward Bailey Glacier. As the lake filled up, the water started to lift the glacier, resulting in a 25-kilometer-long, carved-out tunnel underneath the ice. The pressure from the water building up finally caused it to burst into Scoresby Sound, the largest fjord on Earth.

The phenomenon of a glacial lake gradually filling and releasing its meltwater in a rush is known as a Glacial Lake Outburst Flood (GLOF).

Events such as this have been happening more often in the past 30 years due to global heating and climate change.

“The danger from glacier-dammed lakes is increasing due to global warming. It’s vital to improve our understanding of this phenomenon to issue timely warnings should there be an imminent risk,” Grinsted warned.

The recent GLOF in East Greenland did not cause any harm due to the area’s sparse population. However, floods like this can be catastrophic in more populated areas such as the Himalayas, where villages are frequently destroyed. A 2023 study found that 15 million people globally live under threat of dangerous glacial floods.

“I expect that we will witness outbursts from even larger ice-dammed lakes as Greenland’s ice sheet retreats in coming centuries. At the end of the last Ice Age, Lake Missoula had an outburst that was 2,500 times larger than the recent Catalina event. To understand these massive forces, we must study the largest outbursts when they occur,” Grinsted said. “In this case, the energy released by the glacier flood was equivalent to the output of the world’s largest nuclear power plant running at full capacity for 22 days.”

Grinsted said it was worth considering how the incredible power of such natural phenomena could be harnessed as a green energy source. The energy produced by the event at Catalina Lake could theoretically have generated 50 megawatts of electricity, which is enough to power a small town.

In this instance, however, the closest human settlement of 350 residents was 180 kilometers away, which would pose a major technological challenge for energy transmission and potential use.

“As with many other natural resources in Greenland, infrastructure is a problem. But if a brilliant engineer could figure out how to harness these meltwater outbursts, there’s enormous power and energy potential in them,” Grinsted concluded.

“The danger from glacier-dammed lakes is increasing due to global warming. It’s vital to improve our understanding of this phenomenon to issue timely warnings should there be an imminent risk,” says Grinsted.

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