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Glaciers are melting faster than thought

alarms about the Melting of the Greenland and Antarctic ice there is on a regular basis. They are the visible evidence of the climate change . Less the case g

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Glaciers are melting faster than thought

alarms about the Melting of the Greenland and Antarctic ice there is on a regular basis. They are the visible evidence of the climate change . Less the case glaciers in the case of the global Domestic. An international research now provides team under the leadership of the ETH Zurich and the Swiss Federal research Institute WSL in Birmensdorf Institute of new Numbers to think about. The scientists have the distribution of the volume of Ice and thick worldwide re-calculated and show in yesterday's study, published in the journal "Nature Geoscience": The Eisverlust could go in some regions of the world faster than previously expected.

The scientists have done their calculations for worldwide, around 215'500 glaciers except Antarctica and Greenland. The volume of Ice in comparison to the estimates a few years ago to around 18 percent lower. What is striking is the correction in the mountains is high in Asia, where the glaciers of the Himalayas, the Tibetan plateau and the mountains of Central Asia. The volume of the ice is a quarter smaller, than previous estimates showed. "In the Region, much less Eisreserven seem to be stored than previously thought," says lead author Daniel Nine, a Glaciologist at the ETH Zurich and the Swiss Federal research Institute WSL.

the glacier water

The scientists now expect that the Asian glaciers could lose ten years earlier, by 2060, half of their surface area. The researchers expect with a warming of 1.8 degrees Celsius. For comparison: The climate goal in Paris climate agreement is to prevent a warming of 1.5 to 2 degrees from pre-industrial time.

The revised estimates of the Ice volume can also have consequences for the countries at the foot of the Asian high mountains: The water supplies, so the models would have to face in the summer months up to the year 2090, with a quarter less glacial melt water. "You have to take seriously, the new Numbers are a Wake-up call," says Nine. Even if the researchers indicate in their study that the uncertainties of the calculations are still large.

Strong model dependence

In the last ten years have been developed different glacier data banks, to which the scientists were able to access. Including those of the World Glacier Monitoring Service, coordinated since 1986 – based in Switzerland – worldwide glacier observation at the University of Zurich and glacier data from 35 countries collects; information about the ice thickness of individual glaciers. Satellite data and aerial photographs provided information about the areas and the distribution of the glacier. More specific the research team using digital surface models of the glacier shape. These include estimates of the mass balance of each glacier, the balance of the annual Eiszuwachs and the deposition amount. This results in the glacier flow can be calculated and finally, the ice thickness estimate.

In contrast to earlier calculations, the glaciologists used this time not only a single computer model, but five independent simulations. "This makes the estimates more reliable," says Daniel Nine.

Despite the robust data and the strong model dependence of concern to the researchers. "We hope that the new Figures lead to that, especially in the Asian high mountains in the future, more measurements will be carried out", says the ETH-Zurich Glaciologist. The cost of this is far less than, for example, for Meteorological data, the need to constantly and daily are recorded. There is no need for a network of measuring stations to measure the thickness of the ice. The surface of the glacier can be via satellite.

the better and The longer the measurement series of data, the more accurately the reality can be represented in the models. "The people in these areas need to know what water supplies may, in future, be expected."

risk for high water

Alone in Nepal more than 6000 rivers and streams bring water from the Himalayas. Most are also fed by melting water from the glacier. Hundreds of millions of people in the catchment area of the Asian high country use this water for the irrigation of the fields, for the production of drinking water and energy. The Chinese Academy of Sciences recently warned against the accelerated Melting of the glaciers in the West of the country. Thus, an increased risk for high water. But only in the years of the great melt. The ice is lost, drying out the Land.

Add to that probably the volume of Ice in this Region is smaller than assumed. The new calculations, however, are not everywhere to a decrease of the Ice volume. The glaciers at the edges of the Antarctic, which are not associated with the ice sheet, compared to previous estimates, a volume that is nearly a quarter higher. The mass of ice lost in the Arctic to 17 percent.

The largest volume of Ice represented by the scientists in the Arctic – half of the mass of all domestic is almost glacial. The water reserve in the glaciers is huge: Would the melting of the ice in total, the sea level would rise according to the new calculations, by about 30 centimeters.

development difficult

The sea level rise is considered to be one of the major threats posed by climate change to estimate.

The Melting of the ice sheets in Antarctica and Greenland have led in recent decades to an increase. Areas are mainly affected Islands, and densely populated coast.

It is for the science, however, a difficult task to estimate the size of the ice masses under the ongoing global warming will behave in the next few decades. The show two studies published last week in the journal "Nature".

(editing Tamedia)

Created: 12.02.2019, 07:32 PM

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