Melting of the Greenland ice sheet could raise sea levels by 0.5 inches by the end of the century

A new study has warned that melting ice sheets in northeastern Greenland could cause sea levels to rise by half an inch by the end of the century.

This equals the contribution made by the entire Greenland ice sheet over the past 50 years, which means that the rate of ice loss has been significantly underestimated.

Researchers from Denmark and the United States used satellite data and numerical models to examine ice loss from cover since 2012.

They found that it could contribute up to six times more to global sea level rise by 2100 than climate models currently predict.

Lead author Shfaqat Abbas Khan, from the Technical University of Denmark, said: ‘The models are mostly tuned to observations at the front of the ice sheet, which is easily accessible and where obviously a lot is going on. اشياء.

“Our data shows us that what we see happening in the foreground goes back to the core of the ice sheet.”

Researchers from Denmark and the United States used satellite data and numerical models to examine ice loss on the plate since 2012. Pictured: A satellite image from August 2021 showing the breakup of the Zakaria Glacier

A: 2007 ice velocity map. The black dotted line indicates the combined drainage of the two glaciers. The blue box indicates the magnified area. B: Picture of a satellite receiving station setup, which consists of an antenna, receiver (in the orange box) and a solar panel (top of the box). All of them are located on a platform about 2 meters above the ice surface. A: A satellite image showing NEGIS and the two glaciers. The color indicates the surface velocity derived from the satellite. The locations of the three space stations are marked with yellow boxes

How does global warming affect ice reduction?

Global warming is causing warming worldwide, but is especially important at latitudes closest to the poles.

Permafrost, glaciers, and ice caps struggle to survive in the face of global warming.

For example, melting ice on the Greenland ice sheet results in “meltwater lakes”, which then contribute to further melting.

This positive feedback loop is also found on mountaintop glaciers, many of which have been frozen since the last ice age.

Some animal and plant species depend on the cold conditions provided by glaciers and migrate to higher altitudes to find suitable habitats, putting pressure on ecosystems.

The lack of ice on the mountains also increases the risk of landslides and volcanic eruptions.

Dr Khan added: ‘We can see that the entire basin is getting thinner and the surface velocity is going up.

“Every year, the glaciers we studied retreat inland, and we expect this to continue for decades and centuries to come.

“With the current climate impact, it’s hard to imagine how this decline could be stopped.”

The North East Greenland Ice Stream (NEGIS) is a fast-moving area of ​​ice within the ice sheet.

About 12% of the inner layer of the aquifer drains by two offshore outlet glaciers: the Nioghalvfjerdsfjord Gletscher and Zachariae Isstrøm.

In 2012, the intrusion of warm ocean currents into the ice shelf of the Zacharias Esstrom glacier caused it to collapse.

This event is believed to have boosted NEGIS’s productivity since then, but it’s not clear exactly how much.

This means that the extent of ice thinning from the glacier is also uncertain, as well as its contributions to sea level rise.

For their study, published today in Nature, the international team used GPS navigation satellites to study how widespread the accelerating ice flow is inland.

Satellites measure ice velocity using three receiving stations located on the ice stream, between 56 and 118 miles (90 and 190 km) inside the glacier.

Co-author Eric Regno, from the University of California, Irvine, said: “Data collected from the vast interiors of the ice sheets help us better represent the physical processes embedded in numerical models, and thus provide more realistic predictions of global sea level. go up.

The satellites collected data from 2016 to 2019, which has been combined with data on surface elevations and flow accelerations since 2012.

All of these measurements were eventually used to improve the laws of friction for a numerical model that could predict future ice loss.

The ice was found to have thinned as much as 10 feet (three meters) since 2011 and extended at least 124 miles (200 kilometers) inland. From the coast of Greenland.

Pictured: easing along the flow line from April 2011 to April 2021

Models suggest that this relief will continue at an accelerating rate throughout this century and raise sea levels by as much as 0.6 inches (15.5 mm).

Co-author Dr Matthew Morlighem, from Dartmouth College, said: ‘The Greenland ice sheet is not necessarily more stable than we thought, but it may be more sensitive to changes around the coast.

“If true, the contribution of ice dynamics to the overall mass loss in Greenland would be greater than current models suggest.

“It’s possible that what we find in northeastern Greenland is happening in other areas of the ice sheet.”

The study found that the ice has thinned up to 10 feet (3 meters) since 2011 and extended at least 124 miles (200 km) inland from the Greenland coast. Left: Lake and river on the Zacharias Glacier, northeastern Greenland. Right: A river of meltwater on the Zacharias glacier

In addition, although the winter of 2021 and the summer of 2022 were particularly cold, the NEGIS glaciers continued to retreat.

Northeast Greenland is described as an “Arctic desert” because of its low precipitation, which means the ice sheet is not replenished enough to compensate for its melting.

The researchers say that as technology advances, we may find that our current estimates of sea level rise will need to be corrected upwards.

They hope their study of how upstream sections of glaciers and their melt are related will help with these future predictions.

Greenland may be vulnerable to climate change due to rising air and sea temperatures

New research shows that climate change may have a greater impact on melting Greenland’s ice sheet than previously thought.

A study from the University of Edinburgh and the University of California at San Diego found that rising air temperatures amplify the effects of melting caused by warming oceans.

Warmer air works in tandem with rising ocean temperatures to accelerate ice loss from the world’s second largest ice cap.

Dr Donald Slater, from the University of Edinburgh’s School of Earth Sciences, said the effect we studied is a bit like ice cubes melting into a drink.

It is clear that ice cubes melt faster in hot drinks than in cold drinks, and thus the edges of the Greenland ice sheet melt faster if the ocean is warmer.

“But the ice cubes in the drink will also melt faster if you stir the drink, and rising air temperatures in Greenland are causing the ocean to move closer to the ice sheet, causing the ice sheet to melt faster. Glacier by the ocean.”

Learn more here

Underwater melting occurs when high air temperatures melt the surface of the ice sheet, resulting in melt water that flows into the ocean and creates turbulence. The turbulence causes the ocean to warm up, causing the edges of the submerged ice cap to melt.