Half of the glaciers will disappear with 1.5 degrees of warming

Mountain glaciers, continuous ice sheets other than the Greenland and Antarctic ice sheets, are an important water source for about two billion people and are threatened by climate change. Glacier mass loss affects sea level rise, water resources and natural hazards.

Lead author of the new study, David Rounce, conducted his doctoral research from 2013 to 2017 on the Imja-Lodse Shaar glacier in the Himalayas. There, Rones and his team measured the glacier as it receded rapidly and the lake at its base grew.

According to a study, the world’s glaciers could lose up to 40% of their mass by 2100.

In addition to the Greenland and Antarctic ice sheets, the scientists modeled glaciers around the world to assess how they would be affected by global temperature increases of 1.5 to 4 degrees Celsius (2.7 to 5 degrees Fahrenheit) beyond pre-industrial levels.

According to the study, 50% of the world’s glaciers will melt with 1.5 degrees Celsius of warming, contributing to a 9 centimeters (3.5 inches) rise in sea levels by 2100. All glaciers in central Europe, western Canada and the United States (including Alaska in the US) will melt if the world warms by 2.7 degrees, according to the UN Climate Change Action Plan. Estimated temperature increase based on climate commitments made at the Conference of the Parties to the Framework Convention (COP26). If global warming exceeds 4°C, 80% of the world’s glaciers will disappear and cause a 15-centimeter (6-inch) sea-level rise.

As temperatures rise, glaciers lose a lot of mass. This first modeling study uses satellite-derived mass change data describing the world’s 215,000 glaciers. The team’s state-of-the-art model used “new satellite-derived datasets not available globally.

For this study, scientists used data from NASA’s Terra satellite and USGS-NASA Landsat 8 and Japan’s Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on ESA’s Sentinel satellites.

The sample was treated as a glacial debris envelope, which includes boulders, silt, soot, dust, and volcanic ash present on the glacier surface. Because of the variable thickness, locating glacial debris is often challenging. However, it is significant because it can affect glacier melting: a thin coating of debris can accelerate melting, whereas a thick layer can insulate and slow it down.

Distant glaciers removed from populated areas are particularly useful climate change indicators. Availability of fresh water, landscapes, tourism, ecosystems, frequency and severity of hazards and sea level rise are affected by rapid melting of glaciers.

Ben Hamlington, head of NASA’s Sea Level Change Panel, said: “Sea level rise is not just a problem for certain places. It is increasing almost everywhere on earth.

Rounce said, „We’re not trying to frame this as a negative image of the loss of these glaciers, but rather how we can make a difference. I think that’s a very important message of hope.

Journal Note:

1. David Rounce, Regine Haag, Fabian Moushon and others. Global glacier change in the 21st century: every increase in temperature. Science. DOI: 10.1126/science.abo1324