Analysis of 220,000 Glaciers Shows Rapid Melting That Has Scientists Worried

Meltwater Stream Connects Morteratsch and Pers Glaciers

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Rapid glacier melt: A roaring meltwater stream links the Morteratsch and Pers Glaciers (r.), Engadine, Switzerland. A couple of years earlier, the glaciers were linked. Credit: ETH Zurich

An worldwide research study group consisting of researchers from ETH Zurich has actually revealed that nearly all the world’s glaciers are ending up being thinner and losing mass’ which these modifications are getting rate. The group’s analysis is the most thorough and precise of its kind to date.

Glaciers are a delicate sign of environment modification – and one that can be quickly observed. Regardless of elevation or latitude, glaciers have actually been melting at a high rate because the mid-​20th century. Until now, nevertheless, the complete degree of ice loss has actually just been partly determined and comprehended. Now a global research study group led by ETH Zurich and the University of Toulouse has actually authored a thorough research study on international glacier retreat, which was released online in Nature on April 28, 2021. This is the very first research study to consist of all the world’s glaciers – around 220,000 in overall – leaving out the Greenland and Antarctic ice sheets. The research study’s spatial and temporal resolution is extraordinary – and demonstrates how quickly glaciers have actually lost density and mass over the previous twenty years.

Rising water level and water shortage

What was when long-term ice has actually decreased in volume nearly all over around the world. Between 2000 and 2019, the world’s glaciers lost an overall of 267 gigatonnes (billion tonnes) of ice each year typically – a quantity that might have immersed the whole area of Switzerland under 6 meters of water every year. The loss of glacial mass likewise sped up greatly throughout this duration. Between 2000 and 2004, glaciers lost 227 gigatonnes of ice each year, however in between 2015 and 2019, the lost mass totaled up to 298 gigatonnes yearly. Glacial melt triggered approximately 21 percent of the observed increase in water level throughout this duration – some 0.74 millimeters a year. Nearly half of the increase in water level is attributable to the thermal growth of water as it warms up, with meltwaters from the Greenland and Antarctic ice sheets and modifications in terrestrial water storage accounting for the staying 3rd.

Skaftafelljökull Glacier

Iceland’s glaciers – here Skaftafelljökull – have likewise quickly lost mass over the past 20 years. Credit: P. Rüegg / ETH Zurich

Among the fastest melting glaciers are those in Alaska, Iceland, and the Alps. The circumstance is likewise having an extensive impact on mountain glaciers in the Pamir mountains, the Hindu Kush, and the Himalayas.

“The situation in the Himalayas is particularly worrying,” describes Romain Hugonnet, lead author of the research study and scientist at ETH Zurich and the University of Toulouse. “During the dry season, glacial meltwater is an important source that feeds major waterways such as the Ganges, Brahmaputra and Indus rivers. Right now, this increased melting acts as a buffer for people living in the region, but if Himalayan glacier shrinkage keeps accelerating, populous countries like India and Bangladesh could face water or food shortages in a few decades.”

The findings of this research study can enhance hydrological designs and be utilized to make more precise forecasts on an international and regional scales – for example, to approximate just how much Himalayan glacier meltwater one can expect over the next couple of years.

To their surprise, the scientists likewise recognized locations where melt rates slowed in between 2000 and 2019, such as on Greenland’s east coast and in Iceland and Scandinavia. They associate this divergent pattern to a weather condition anomaly in the North Atlantic that triggered greater rainfall and lower temperature levels in between 2010 and 2019, thus slowing ice loss. The scientists likewise found that the phenomenon called the Karakoram abnormality is vanishing. Prior to 2010, glaciers in the Karakoram range of mountains were steady – and in many cases, even growing. However, the scientists’ analysis exposed that Karakoram glaciers are now losing mass too.

Study based upon stereo satellite images

As a basis for the research study, the research study group utilized images caught on board NASA’s Terra satellite, which has actually been orbiting the Earth when every 100 minutes because 1999 at an elevation of almost 700 kilometers. Terra is house to ASTER, a multispectral imager with 2 cams that tape-record sets of stereo images, enabling scientists to produce high-​resolution digital elevation designs of all the world’s glaciers. The group utilized the complete archive of ASTER images to rebuild a time series of glacial elevation, which allowed them to determine modifications in the density and mass of the ice over time.

Lead author Romain Hugonnet is a doctoral trainee at ETH Zurich and the University of Toulouse. He dealt with this task for almost 3 years and invested 18 months evaluating the satellite information. To procedure the information, the scientists utilized a supercomputer at the University of Northern British Columbia. Their findings will be consisted of in the next Assessment Report of the United Nations Intergovernmental Panel on Climate Change (IPCC), which is because of be released later on this year. “Our findings are important on a political level. The world really needs to act now to prevent the worst-​case climate change scenario,” states co-​author Daniel Farinotti, head of the glaciology group at ETH Zurich and the Swiss Federal Institute for Forest, Snow and Landscape Research WSL.

Reference: “Accelerated global glacier mass loss in the early twenty-first century” by Romain Hugonnet, Robert McNabb, Etienne Berthier, Brian Menounos, Christopher Nuth, Luc Girod, Daniel Farinotti, Matthias Huss, Ines Dussaillant, Fanny Brun and Andreas Kääb, 28 April 2021, Nature.
DOI: 10.1038/s41586-021-03436-z

Alongside the University of Toulouse, ETH Zurich and WSL, other organizations that took part in the research study consist of Ulster University in the UK, the University of Oslo in Norway and the University of Northern British Columbia in Canada (please describe the research study for a total list).

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