Rapid melting of Petermann Glacier signals even worse sea level rise

A shocking study of Petermann Glacier in northwest Greenland by researchers from the University of California, Irvine (UCI) and NASA’s Jet Propulsion Laboratory has revealed a previously unknown interaction between ice and ocean. 

This leads to the possibility that the climate community has been significantly underestimating the impact of polar ice deterioration on future sea level rise. This important discovery could have far-reaching implications for our understanding of climate change and its consequences.

The team of scientists used satellite radar data from three European missions to analyze the behavior of Petermann Glacier’s grounding line, where the ice detaches from the land bed and begins floating in the ocean. 

What the researchers found at Petermann Glacier

Contrary to previous beliefs, they found that the grounding line shifts substantially during tidal cycles, allowing warm seawater to intrude and accelerate ice melt. The findings are detailed in a paper published in Proceedings of the National Academy of Sciences.

Lead author Enrico Ciraci, UCI assistant specialist in Earth system science and NASA postdoctoral fellow, explained: “Petermann’s grounding line could be more accurately described as a grounding zone because it migrates between 2 and 6 kilometers as tides come in and out. This is an order of magnitude larger than expected for grounding lines on a rigid bed.” 

The traditional view of grounding lines beneath ocean-reaching glaciers did not account for this migration or ice melt during tidal cycles. However, the new study reveals that warm ocean water penetrates beneath the ice through preexisting subglacial channels, leading to the highest melt rates at the grounding zone.

As the glacier’s grounding line retreated nearly 4 kilometers (2½ miles) between 2016 and 2022, the researchers observed that warm water carved a 670-foot-tall cavity in the underside of the glacier. Remarkably, this cavity persisted throughout 2022.

Senior co-author Eric Rignot, UCI professor of Earth system science and NASA JPL research scientist, emphasized the significance of these findings, stating, “These ice-ocean interactions make the glaciers more sensitive to ocean warming.”

Models for future sea level rise must now be rebuilt

Current models do not include these ice-ocean dynamics, which, if accounted for, could increase projections of sea level rise by up to 200 percent – impacting not just Petermann Glacier but all glaciers ending in the ocean, including those in northern Greenland and Antarctica. 

This discovery highlights the urgent need to update our understanding of glacier behavior in response to climate change.

The paper emphasizes that the Greenland ice sheet has lost billions of tons of ice to the ocean in recent decades, primarily due to warming of subsurface ocean waters – a consequence of Earth’s changing climate. 

Rignot explains that exposure to ocean water vigorously melts ice at the glacier front, eroding resistance to the movement of glaciers over the ground and causing the ice to slide more quickly into the sea. 

This groundbreaking research underscores the importance of refining our climate models to predict the future consequences of climate change and inform our response to this global crisis more accurately.

More about Petermann Glacier

Petermann Glacier is a large and significant glacier located in northwest Greenland. It is one of the largest floating ice shelves in the Northern Hemisphere, extending over an area of approximately 1,295 square kilometers. 

The glacier is fed by the Greenland Ice Sheet and discharges into the Nares Strait, which separates Greenland from Ellesmere Island in the Canadian Arctic Archipelago. Petermann Glacier plays a vital role in draining the Greenland Ice Sheet and contributes to global sea level rise through the calving of icebergs and melting of its ice.

Several aspects make Petermann Glacier a subject of interest for climate scientists and glaciologists:

Ice shelf dynamics

The floating ice shelf at the terminus of Petermann Glacier is crucial for understanding the stability and dynamics of ice shelves. The interaction between the ice shelf and ocean waters provides insights into how ocean warming can impact ice shelf stability and glacier flow.

Calving events

Petermann Glacier has experienced several major calving events in recent years, with the most notable ones occurring in 2010 and 2012. These events resulted in the detachment of massive icebergs from the glacier’s floating ice shelf, raising concerns about the stability of the glacier and its contribution to sea level rise.

Grounding line migration

A recent study by researchers from the University of California, Irvine, and NASA’s Jet Propulsion Laboratory revealed that the grounding line of Petermann Glacier, where the ice detaches from the land bed and starts to float, migrates between 2 and 6 kilometers during tidal cycles. This previously unknown interaction between ice and ocean allows warm seawater to infiltrate and accelerate ice melt, potentially leading to underestimations of sea level rise caused by polar ice deterioration.

Climate change and sea level rise

Petermann Glacier, along with other glaciers in Greenland, is losing ice due to climate change. As a consequence of increasing temperatures and subsurface ocean warming, the glacier is melting at a faster rate, contributing to global sea level rise.

Research and monitoring

Due to its significance in understanding glacier dynamics, ice-ocean interactions, and the impact of climate change on ice sheets, Petermann Glacier has become a focal point for researchers and is closely monitored using satellite data, field measurements, and remote sensing techniques.

In summary, Petermann Glacier is a crucial component of the Greenland Ice Sheet and plays a vital role in understanding the impacts of climate change on glacier dynamics, ice-ocean interactions, and global sea level rise. Its behavior and stability have far-reaching implications for coastal communities and ecosystems worldwide.

More about global sea level rise

Global sea level rise is one of the most critical consequences of climate change, posing a significant threat to coastal ecosystems, infrastructure, and human populations. As Earth’s climate warms due to the increase in greenhouse gases, such as carbon dioxide and methane, two primary factors contribute to the rising sea levels: thermal expansion of ocean waters and the melting of land-based ice.

Thermal expansion

As ocean temperatures increase, seawater expands, occupying more volume. This expansion, known as thermal expansion, contributes to approximately half of the observed sea level rise. The upper layer of the ocean, which is in direct contact with the atmosphere, warms faster, causing water to expand and occupy more space, subsequently leading to a rise in sea level.

Melting of land-based ice

The melting of ice sheets and glaciers also contributes significantly to sea level rise. Ice sheets in Greenland and Antarctica contain vast amounts of frozen water, and their accelerated melting due to climate change has a substantial impact on global sea levels. Additionally, the melting of mountain glaciers worldwide, particularly in regions like the Himalayas, the Andes, and the Alps, adds to the rising sea levels.

Recent research suggests that ice loss from Greenland, Antarctica, and mountain glaciers has accelerated over the past few decades, causing the rate of global sea level rise to increase. From 1993 to 2021, the global sea level rose at an average rate of approximately 3.3 millimeters per year, and this rate is projected to increase further as climate change intensifies.

The consequences of sea level rise are far-reaching and pose significant risks to coastal communities, infrastructure, and ecosystems. Some of the most severe impacts include:

Flooding and erosion

As sea levels rise, the frequency and severity of coastal flooding and erosion increase, putting lives, property, and infrastructure at risk.

Saltwater intrusion

Rising sea levels can cause saltwater to intrude into freshwater resources, such as rivers and aquifers, threatening freshwater supplies and agricultural lands.

Loss of coastal habitats

Sea level rise can lead to the loss of vital coastal habitats, such as wetlands, mangroves, and coral reefs, which provide essential ecosystem services and act as natural barriers against storm surges and erosion.

Displacement of human populations

Low-lying coastal areas and small island nations are particularly vulnerable to sea level rise, which can lead to the displacement of millions of people, creating significant social, economic, and political challenges.

Mitigating global sea level rise requires urgent and concerted efforts to reduce greenhouse gas emissions, promote climate adaptation strategies, and improve our understanding of ice sheet dynamics and ocean processes. As the impacts of sea level rise are already being felt worldwide, it is crucial to act now to reduce future risks and protect vulnerable communities and ecosystems.

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