Photo: DTU Space

Climate change can alter Greenland drastically

Friday 21 Jun 19

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Shfaqat Abbas Khan
Professor
DTU Space
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If climate change continues unabated, all the ice in Greenland may melt away in the course of just a thousand years and will lead to significant changes in the environment.

The Greenland ice sheet holds enough water to result in sea levels rises of up to 7.3 metres, if it melts. And it is melting already, but only by an amount corresponding to a global sea level rise of about 0.5 millimetres a year in recent decades.

Now, a research team, with participation from DTU Space, has made a projection of what will happen in the long term.

Here the forecasts—based on a projection of data on the development in recent decades—predict that enough ice will have melted in Greenland by the year 2100 to result in sea level rises of up to 33 centimetres. And in about 1,000 years, all the ice may be completely gone.

“We have developed a very accurate model, which predicts that even though melted ice from Greenland during the last 20,000 years has only resulted in a sea level rise of approximately 4.6 metres, the ice that will likely melt in the next 800 to 1,000 years will equal a sea level rise of 7.3 metres. That is a very steep acceleration,” says professor Shfaqat Abbas Khan from DTU Space.

The new knowledge has just been publicized in the online version of the renowned scientific journal Science Advances. 

 Shfaqat Abbas Khan is co-author of the article, which the Danish Meteorological Institute has contributed to as well. The work is led by researchers from the University of Alaska, who are the main authors of the Science article.

"The unpleasant truth is that our calculations show all three scenarios to be highly realistic."
Professor Shfagat Abbas Khan, DTU Space

Overall, the analyses show that melted ice from Greenland will contribute 5-33 cm to the global sea level rise by 2100. In the year 2200, it will be 1.55 metres. And when we reach the year 3000, all the ice may well have melted completely and been converted into a sea rise level of approximately 7.3 metres across the world’s oceans.

This means that all the ice could be gone in 800 to 1,000 years, if climate change continues unabated.

In any case, by then large parts of Greenland will be permanently ice-free and drastically altered.

“This development will transform Greenland completely—when the weight of the enormous amounts of ice disappears, great land uplifts and shifts in land masses will occur. It will change the topography, landscapes, and inlets in a way that it is difficult to imagine,” says Shfaqat Abbas Khan.

A forecast like this has not been done before with such extensive and new data. They have used data from the past three decades that are much more precise and in much larger quantities than in previous forecasts.

The model includes new and more detailed knowledge about glacier movement, deglaciation, and the bedrock’s importance to melting processes. 

The model uses these data as well as input from the UN climate panel IPCC’s scenarios about what happens to the ice, based on the warming currently in progress and the warming expected in the future.

The model has been tested by running known data from the last three decades and seeing how accurately it predicted what has actually happened—and its prediction was quite accurate.
This means that it will also create quite accurate forecasts for the future, based on the three IPCC scenarios RCP 2.6, 4.5, and 8.5 for the development towards the year 3000.

According to RCP 2.6, 8-25 per cent of Greenland’s ice will have melted, equalling a sea level rise of 0.59-1.88 metres. RCP 4.5 predicts an ice-loss of 26-57 per cent, equalling 1.86 to 4.17 metres. While the most dramatic scenario in the forecast predicts that 72 to 100 per cent of the ice will have melted by the year 3000, which will result in a sea level rise of between 5.23 and 7.28 metres across the world’s oceans.

“The unpleasant truth is that our calculations show all three scenarios to be highly realistic. And that even the relatively mild scenario RCP 2.6 can result in a sea level rise of almost 2 metres,” says Shfaqat Abbas Khan.

Watch NASA’s video about the forecast/research, which is, among other things, based on NASA’s Operation IceBridge data, obtained by flights over Greenland with a plane provided with special equipment. 

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