Nestled in the Himalayas, near the base of Mount Everest, the Imja-Lhotse Shar Glacier witnessed a dramatic transformation as it dwindled in size while the lake at its base expanded. Over a four-year period from 2013 to 2017, David Rounce and his team monitored this glacier’s rapid retreat, a stark testament to the impacts of climate change.
Rounce, now an assistant professor at Carnegie Mellon University, is the lead author of a groundbreaking study published in January 2023 in the journal Science. The study paints a sobering picture of Earth’s glaciers, projecting that they could lose up to 40% of their mass by 2100. This research, which provides vital insights into the consequences of climate change, encompasses glaciers worldwide, excluding the vast Greenland and Antarctic ice sheets. It seeks to understand how these glaciers will respond to projected global temperature increases ranging from 1.5 to 4 degrees Celsius (2.7 to 5 degrees Fahrenheit) above pre-industrial levels.
The findings are alarming: With a 1.5-degree Celsius rise in temperature, half of the world’s glaciers will vanish, contributing to a sea-level rise of 9 centimeters (3.5 inches) by the end of the century. If global warming reaches 2.7 degrees Celsius—an estimate based on climate commitments made at COP26, the UN Framework Convention for Climate Change—nearly all glaciers in Central Europe, western Canada, and the United States (including Alaska) will have melted. In a worst-case scenario of 4 degrees Celsius warming, a staggering 80% of the world’s glaciers will disappear, elevating sea levels by 15 centimeters (6 inches).
Rounce emphasizes that glacier loss is inevitable, regardless of the temperature increase. “Regardless of temperature increase, the glaciers are going to experience a lot of loss,” he warns.
What sets this study apart is its comprehensive modeling, drawing from satellite-derived mass change data encompassing all 215,000 glaciers worldwide. The team’s advanced model leveraged new satellite-derived datasets, previously unavailable on a global scale, including information from NASA’s Terra satellite, Japan’s Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), as well as data from NASA’s Landsat 8 and ESA’s Sentinel satellites.
The model accounted for an often overlooked factor: glacial debris cover. This layer, composed of rocks, sediment, soot, dust, and volcanic ash on glacier surfaces, is notoriously challenging to measure due to its varying thickness. However, it significantly influences glacier melting. A thin layer can intensify melting, while a thick layer insulates and reduces it.
Glaciers in remote, untouched regions serve as poignant indicators of climate change. Their rapid disappearance has profound consequences, impacting freshwater supplies, landscapes, tourism, ecosystems, hazard frequency and severity, and global sea levels.
Ben Hamlington, leader of NASA’s Sea Level Change Team, emphasizes that sea-level rise is not confined to specific locations but is a global issue that affects almost every corner of the Earth.
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