Pine Island-gletsjeren er blandt de ismasser, der bidrager til den accelererende afsmeltning af is fra det vestlige Antarktis. Billedet er fra 2017, hvor et 1-2 km langt stykke is brækkede af gletsjeren - midten af billedet. (Foto: NASA)

Antarctica has suffered massive loss of ice since 1992

Wednesday 13 Jun 18

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René Forsberg
Professor, Head of Geodynamics
DTU Space
+45 45 25 97 19

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Shfaqat Abbas Khan
Associate Professor
DTU Space
+45 45 25 97 75

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Valentina Roberta Barletta
Post doc
DTU Space
+45 45 25 97 36

DTU Space in international Antarctic ice cooperation

 

 

  • The research is an outcome of the ESA-NASA Ice Sheet Mass Balance Inter-comparison Exercise (IMBIE) and is supported by NASA and the European Space Agency, ESA.

New research show that accelerating ice loss from Antarctica have increased sea levels by 7.6 mm since 1992. DTU Space has contributed to the study mapping 25 years of Antarctic ice loss.

The study published in the scientific journal Nature show that ice loss from Antarctica has increased over the last 25 years resulting in a 7.6 mm increase in global sea levels. The research has been conducted by an international team of scientists.

Their findings covering the period 1992 til 2017 show that, prior to 2012, Antarctica lost ice at a steady rate of 76 billion tonnes per year resulting in a 0.2 mm per year contribution to sea level rise. However, since then there has been a sharp, threefold increase. 

Between 2012 and 2017 the continent lost 219 billion tonnes of ice per year corresponding to a 0.6 mm per year sea level contribution. Or put in another way: Ice corresponding to 600 million cubic meters of water has melted of Antarctica every day in the last five years.

“We have long suspected that changes in Earth’s climate will affect the polar ice sheets. Thanks to the satellites our space agencies have launched, we can now track their ice losses and global sea level contribution with confidence,” said professor Andrew Shepherd at the University of Leeds who led the assessment together with Dr Erik Ivins at NASA’s Jet Propulsion Laboratory in California.

“According to our analysis, there has been a step increase in ice losses from Antarctica during the past decade, and the continent is causing sea levels to rise faster today than at any time in the past 25 years.”

The findings are from a major climate assessment known as the ‘Ice Sheet Mass Balance Inter-comparison Exercise’ (IMBIE). Some 84 scientists from 44 international organizations have combined 24 satellite surveys of Antarctica to produce the assessment.

According to Erik Ivins from NASA’s Jet Propulsion Laboratory it is “the most robust study of ice mass balance of Antarctica to date”.

Specialist contribution from DTU Space

Antarctica stores enough frozen water to raise global sea level by 58 metres if it all melted. Knowing how much ice it is losing is key to understanding the impacts of climate change today and in the future.  

“No matter what method or technique you use, there is a clear evidence of accelerated ice loss from the Antarctic ice sheet,” said associate professor, Shfaqat Abbas Khan, one of the contributing authors to the study, from the National Space Institute, DTU Space, at the Technical University of Denmark.

DTU Space contributed to the study with specialist knowledge by providing Antarctica mass balance estimates based on satellite radar measurements, measurement of changes in the earth gravity field from satellites, as well as new models for changes of land uplift in Antarctic when the ice load diminishes called GIA.

"There is a clear evidence of accelerated ice loss from the Antarctic ice sheet"
Shfaqat Abbas Khan, associate professor at DTU Space

"The GIA effects have until recently been quite unknown in Antarctica. But new data on land uplift and new models, means we now have a much better understanding of this process in Antarctica, and the estimates of melt therefore are more accurate”, says scientist Valentina Barletta, another DTU Space author on the study.

Antartica has an impact on the northern hemisphere

It is GIA effects and change in the Earth’s gravity field when the ice melts, that make the Antarctica ice melting more important for the northern hemisphere than the melting in Greenland.

This in spite of the fact that the Greenland ice sheet melting still is around double the melt of Antarctica.

“The global sea level rise due to ice sheet melt is not uniformly distributed, and the Antarctica melt actually has a direct impact on Danish sea levels, whereas the role of the Greenland melt is close to zero for us. So the accelerating melt in Antarctica is an important issue for us and the huge question is if this will continue in the years to come,” said professor at DTU Space René Forsberg who also contributed to the study.

Most changes in West Antarctica

The threefold increase in ice loss from the continent as a whole is a combination of glacier speedup in West Antarctica and at the Antarctic Peninsula, and reduced growth of the much bigger East Antarctica ice sheet.

West Antarctica experienced the largest change, with ice losses rising from 53 billion tonnes per year in the 1990s to 159 billion tonnes per year since 2012. Most of this came from the huge Pine Island and Thwaites Glaciers, which are retreating rapidly due to ocean melting from below.

At the northern tip of the continent, ice shelf collapse at the Antarctic Peninsula has driven a 25 billion tonne per year increase in ice loss since the early 2000s.  

On the other hand the East Antarctic ice sheet has remained close to a state of balance over the past 25 years, gaining just 5 billion tonnes of ice per year on average.

DTU Space and University of Leeds scientists on joint mission in Antarctica January 2018 to conduct airborne and in-situ satellite validation for ESA at Stange Ice shelf, at the Antarctic Peninsula. (Photo: DTU Space)

DTU Space and University of Leeds scientists on joint mission in Antarctica January 2018 to conduct airborne and in-situ satellite validation for ESA at Stange Ice shelf, at the Antarctic Peninsula. (Photo: DTU Space)

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