It is a gigantic number: 9625 billion tons of glacial ice are melted in the last 50 years, from 1961 to 2016, worldwide. And the huge, flat ice sheets in Greenland and Antarctica are not included once.

Michael Zemp, a Glaciologist at the University of Zurich, illustrates this with a comparison: “That would be a block of ice the size of Switzerland with a thickness of 250 meters.” Zemp directs the World Glacier Monitoring Service (WGMS); together with an international team of researchers, he has measured the global glacier landscape, and the data, yesterday in the scientific magazine “Nature” published.

The current global Eisverlust is according to the investigation, a year is about 335 billion tons. This corresponds to about three times the remaining glacier volume in the European Alps. “Globally, our new melting estimates, about 18 percent higher than in previous studies,” says Michael Zemp.

Huge data set

The scientists, the new data compares with the last IPCC report, which was released in 2013. At that time, the projections on the buildings, on field measurements of 500 glaciers that were measured in the context of the World Glacier Monitoring part is already 125 years ago. The glaciological field measurements provide the annual eisschwan gifts. This data came from 2003 to 2009, the Grace satellite, which makes gravitational measurements, and Icesat, which measures use of lasers. The satellite data of the absolute Eisverlust can be estimated over several years or decades.

However, both methods of measurement are ice sheets, among other things, due to the low spatial resolution, especially for large, but less for smaller glaciers. The Swiss Alps, for example, Grace is only as a point.

For the new estimates, the team of researchers, in addition to geodetic satellites data used, with which a digital elevation mesh can be stretched over the earth. “To make the two different times, one can infer the change in the ice thickness,” says Zemp. The researchers were able to model in addition to the 500 glaciers, the change of the thickness of the ice, with a further 19’000 ice and on the whole of the 19 glacier regions. Approximately 10 percent of the glaciers have been around the world.

Large uncertainties

Now the records from all regions of the world are, according to Zemp, thanks to a single method for the first time, which can be compared over a long period of time. However, the uncertainties are also in the new data, depending on the Region, there is still a great.

For example, there are glaciers in Arctic Canada and in the Antarctic there are no statistically detectable change of the ice masses. This is according to Zemp, especially on the lack of data. “Until 1980, the data situation is bad, then you will be better.” However, the new information would make a good picture of the development, says the Zurich Glaciologist. “That the glaciers bad, we knew already for a long time, but now we can quantify the loss.” The current average Eisverlust the glacier of well over 300 billion tons per year, according to the new study, a sea level rise of around a Millimeter which corresponds to the proportion of the Greenland ice sheet on sea-level rise.

The scientists believe that the sea level has risen since 1961 by the melting glacier of approximately 27 mm. The largest share originates from the glaciers in Alaska, the influence of glacier melt in the Alps, however, is very small.

Overall, the sea level has risen in the last hundred years by around 200 millimeters. Around 70 percent of which were caused by the melting of the glaciers and the two ice sheets in Greenland and Antarctica. The Rest came about because the sea water is heated and thus expands.

researchers at the German Potsdam Institute for climate impact research are of the view that climate change is already inevitable future rise in sea level. This means that The consequences of global warming – an average of about one degree in the last hundred years – will be partially felt in the next decades or centuries. Their models show that global sea level will rise up to 2300 between 0.7 and 1.2 meters, even if the Paris climate agreement is fully implemented. The greenhouse gas emissions before 2050 would “bolt for the important control for the future sea-level”. (Editorial Tamedia)

Created: 08.04.2019, 16:55 PM