NASA: Earth's warming climate shrinks glaciers by 50 percent

Estimating reducing glaciers

The team observed the growing lake at the base for about five years in Nepal and collected data by measuring the receding glaciers.

Rounce stated: “To go to the same place and to see the lake expand and see how the glacier was thinning rapidly was quite eye-opening, to say the least.”

The study projected that the world’s glaciers could lose as much as 40 percent of their mass by 2100. This conclusion was driven after initiating computer simulations and making a model of glaciers worldwide, excluding the Greenland and Antarctic ice sheets.

The model aimed to predict the outcome of melting glaciers if Earth’s temperatures increased by 1.5 to 4 degrees Celsius (about 2.7 to 5 degrees Fahrenheit) compared to pre-industrial levels. 

After applying the model, researchers found that “with 1.5 degrees Celsius of warming, 50 percent of the world’s glaciers would disappear and contribute nine centimeters (3.5 inches) to sea level rise by 2100,” NASA reported. 

Additionally, if the planet gets warmer by 2.7 degrees Celsius because of the promises made at a big climate conference (COP26), almost all glaciers in Central Europe, western Canada, and the United States (including Alaska) will melt away. 

If the temperature increases by four degrees Celsius, 80 percent of the world’s glaciers will disappear. As a result, they will contribute about 15 centimeters (six inches) to the sea level rise.

The ocean water levels will rise, too, which can generate difficulties for places near the coast. “Regardless of temperature increase, the glaciers are going to experience a lot of loss,” Rounce said. “That’s inevitable.”

Satellite-drive data model

The model deployed utilized satellite-driven mass change data, making this the first study to do so. It helped narrow down all the 215,000 glaciers in the world. 

Regine Hock, a glaciology professor at the University of Alaska and the University of Oslo, stated that the team’s model operated new satellite-derived datasets that were not available globally.

According to NASA, it included data from Japan's Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite and the USGS-NASA Landsat 8 and ESA's Sentinel satellites.

Furthermore, the model considered the glacial debris cover, which included rocks, sediment, soot, dust, and volcanic ash found on the glacier surface.

Despite the challenge in measuring glacier debris due to its varying thickness, researchers considered it imperative to record it as it can potentially influence glacier melting.

“A thin layer of debris can enhance melting, while a thick layer can insulate and reduce it,” stated NASA.

The consequential impact of diminishing glaciers from remote regions far from human activities is enormous. Such critical situations act as solid markers of climate change. 

The accelerating depletion is affecting freshwater availability, alerting landscapes and tourism, disrupting ecosystems, influencing the occurrence and severity of hazards, and contributing to rising sea levels. 

Ben Hamlington, NASA's Sea Level Change Team leader, stated: “Sea level rise is not just a problem for a few specific locations. It’s increasing almost everywhere on Earth.”

“We are not trying to frame this as a negative look at the loss of these glaciers, but instead how we have the ability to make a difference,” Rounce said. “I think it’s a very important message: a message of hope.”

The study was published in January 2023 in the journal – Science.

Study abstract: 

Glacier mass loss affects sea level rise, water resources, and natural hazards. We present global glacier projections, excluding the ice sheets, for shared socioeconomic pathways calibrated with data for each glacier. Glaciers are projected to lose 26 ± 6% (+1.5°C) to 41 ± 11% (+4°C) of their mass by 2100, relative to 2015, for global temperature change scenarios. This corresponds to 90 ± 26 to 154 ± 44 millimeters sea level equivalent and will cause 49 ± 9 to 83 ± 7% of glaciers to disappear. Mass loss is linearly related to temperature increase and thus reductions in temperature increase reduce mass loss. Based on climate pledges from the Conference of the Parties (COP26), global mean temperature is projected to increase by +2.7°C, which would lead to a sea level contribution of 115 ± 40 millimeters and cause widespread deglaciation in most mid-latitude regions by 2100.