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Greenland's Petermann Glacier melting rate has tripled due to warm ocean water

A colossal river of ice, Greenland’s Petermann Glacier, is disintegrating with shocking speed. Since the early 2000s, its melting rate has tripled. Rising tides threaten to inundate coastal cities and displace millions worldwide.

Researchers from the University of California, Irvine (UCI), and NASA’s Jet Propulsion Laboratory (JPL) have pinpointed the intrusion of warm ocean water beneath the glacier as a key factor.

Shifting with the tides

Scientists were initially baffled by how quickly Petermann Glacier was losing ice. That’s when they made a remarkable discovery: the glacier isn’t fixed in place. Instead, it shifts by kilometers with the changing tides.

“Satellite data revealed that the glacier shifts by several kilometers – or thousands of feet – as tides change,” explained Ratnakar Gadi, UCI PhD candidate and lead author of the study.

The team mapped this massive movement and its impact on the ice. What they found shifts our entire understanding of how glaciers interact with the ocean.

The grounding zone

While scientists are used to thinking about the impact of warming air temperatures on ice, the real action is happening beneath the surface. Warmer seawater is making its way far beneath Petermann Glacier, thinning it from below.

Researchers found the highest melt rates at a crucial area called the “grounding zone.” This zone is where the glacier transitions from resting on land to floating on seawater.

“Seawater rises and falls with changes in oceanic tides in that zone and melts grounded ice from below vigorously,” said study senior author Eric Rignot, UCI professor of Earth system science. And the shape of this zone, scientists found, was a major contributor to the rapid melt.

Modeling Petermann Glacier’s melt

To unravel the relative impact of warmer water versus the changing grounding zone, the UCI-led team relied on a sophisticated computer model from the Massachusetts Institute of Technology.

When they only factored in warmer ocean temperatures, the glacier thinned by an estimated 40 meters. But, when they incorporated the expansion of the grounding zone, the modeled ice loss skyrocketed to 140 meters – more than three times as much.

Study implications

The study paints a far more dire picture of the glacier’s future and highlights a fundamental shift in our understanding of ice-ocean interactions. The grounding zone, once viewed as a less significant factor, is now understood to be critical.

Glaciers like Petermann are losing their grip on land and retreating because of this underwater melt. And the retreat has a cascading effect.

“The results published in this paper have major implications for ice sheet modeling and projections of sea level rise,” Rignot said.

“Earlier numerical studies indicated that including melt in the grounding zone would double the projections of glacier mass loss. The modeling work in this study confirms these fears. Glaciers melt much faster in the ocean than assumed previously.”

Insights from the melting glacier

Greenland’s Petermann Glacier melting rate is a stark reminder that climate change isn’t a distant threat; its impacts are being felt right now. While the details are complex, the bottom line is simple: ice is melting, seas are rising.

Every bit of warming and every kilometer of the ice lost pushes coastal communities worldwide closer to the brink. The consequences are immense and demand urgent action.

More about Petermann Glacier

Petermann Glacier is a large glacier located in North Greenland. It is particularly notable for its floating ice tongue, which is one of the largest floating glaciers in the Northern Hemisphere. The glacier is named after the German cartographer August Heinrich Petermann.

Climate change indicator 

Like many glaciers around the world, the Petermann Glacier serves as an important indicator of climate change. Scientists study changes in its size and ice melt patterns to understand the broader impacts of global warming on polar ice and sea levels.

Major calving events

The glacier has experienced significant calving events in recent years, where large sections of the ice tongue have broken off. 

Notable events occurred in 2010 and 2012, when massive ice islands broke away from the glacier. These events attracted global attention and underscored concerns about the stability of polar ice in a warming world.

Research and monitoring

The glacier is an active site for scientific research and monitoring. Researchers use satellite imagery, remote sensing technologies, and on-site measurements to study the glacier’s dynamics, the thickness of the ice, and the rate of ice melt. 

These studies are crucial for understanding not only the fate of the Petermann Glacier but also the broader implications for global sea level rise.

Ecological significance

The area around the glacier is an important habitat for a variety of Arctic wildlife, including polar bears, seals, and various bird species. Changes in the glacier and the surrounding ice can have significant impacts on these ecosystems.

The study is published in the journal Geophysical Research Letters.

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