A supercomputer at the University of Northern British Columbia has helped an international team of researchers discover that the rate of mass loss from Earth’s glaciers is accelerating.
The computer, jointly funded by UNBC and the Hakai Institute, built digital elevation models based on more than 440,000 satellite images.
“Processing digital spatial imagery to measure changes in surface elevation requires enormous computing power,” said Brian Menounos, professor at UNBC and affiliate of Hakai, Canada Research Chair on the change of glaciers. “We needed an equivalent of about 584 modern computers running for about a year to derive these elevation models. On the other hand, the generation of the elevation models required more than five million hours of calculation. “
The calculations are part of an article published in the April 29 issue of Nature which found that between 2000 and 2004, glaciers lost 227 gigatons of ice per year, but that between 2015 and 2019 that rate dropped. to 298 gigatons per year. A gigaton is equivalent to a billion tonnes. Water loss from glaciers accounts for about 21 percent of the observed sea level rise over the past 20 years – about 0.74 millimeters per year.
Researchers, led by ETH Zurich and doctoral student Romain Hugonnet from the University of Toulouse, measured the change in altitude of all of the Earth’s glaciers – around 220,000 in total. Hugonnet is also a former research associate at UNBC.
The researchers used processed satellite images acquired from NASA’s ASTER sensor to measure the change in altitude over glacier terrain over time.
“Computer facilities at UNBC and the Hakai Institute have enabled us to generate time series of surface elevation, essentially time varying topographies, at 100 meters resolution for approximately half a billion individual locations. above the Earth’s glaciers and their surroundings, ”said Hugonnet.
Researchers found that over the past 20 years, mass loss from North American glaciers was about half of the global total, with a quarter coming from glaciers in Alaska and those that straddle the Alaskan border. and Canada.
Glaciers and ice caps in the eastern Canadian Arctic contributed an additional 21 percent, with three percent coming from glaciers in central and southern British Columbia, Alberta and the continental United States .
The researchers also found that some of the highest rates of mass loss in the world over the past decade have occurred in southern Alaska and western Canada.
“In addition to providing a detailed glacier response to regional and climatic variability, the dataset will provide important observational data needed to validate and improve the physical models used to predict changes in glaciers and runoff in them. decades to come, ”says Menounos.
Other key institutions that have co-led this work include the University of Ulster in the UK and the University of Oslo in Norway.