Collaborative research published recently shows that with each temperature increase of 1 degree Celsius in the summer, Alaska glaciers melt for up to three additional weeks.
A single degree Celsius equates to 1.8 degrees Fahrenheit.
The study published in the online journal “Nature” by the University of Alaska Fairbanks and Carnegie Mellon University found that synthetic aperture radar, or SAR, can consistently and automatically monitor glaciers and their snowlines year-round. Those are usually only gauged at the end of the melt season using optical instruments.
SAR data is also more reliable than traditional surface-based optical instruments, according to the study published on Feb. 4 in Nature.
Scientists used the radar data to track the number of glacier “melt days.” A single melt day can be one 24-hour period in which an entire glacier is melting or may consist of multiple days where portions of the glacier melt and eventually reach the glacier’s total surface area equivalent.
An increase in melt days over time signals a longer melt season and accelerates the net loss of ice from a glacier.
The study was led by Albin Wells of Carnegie Mellon. Co-authors were assistant professor David Rounce of Carnegie Mellon and Mark Fahnestock of the UAF Geophysical Institute. Rounce was previously a Geophysical Institute postdoctoral fellow and research associate.
Researchers used European Sentinel-1 radar satellite data to track changes throughout each melt season at nearly all Alaska glaciers larger than about half a square mile from mid-2016 through 2024.
Synthetic aperture radar works by sending microwave pulses toward the ground from a moving aircraft or satellite and combining the returning echoes to create detailed images, even through clouds and in darkness.
Sentinel-1 passes over the same location every 12 days, covering more than 3,000 Alaska glaciers.
The team also found that short-term heat waves caused Alaska’s glaciers to lose up to 28% more of their protective snow cover than in typical years. That percentage is at the scale of individual mountain ranges rather than applying uniformly to each glacier within a mountain range.
Glacier mass balance is the difference between how much snow and ice a glacier gains and how much it loses over time.
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