Glaciers are shrinking faster
Scientists study more than 200,000 glaciers to estimate global ice loss – with distressing results.
Astudy of nearly every glacier on Earth has confirmed they are losing more ice every year. The international research team, led by Roman Hugonnet from the Université de Toulouse in France, found that on average these icy rivers have lost 267 gigatonnes (Gt) of mass per year since 2000. A Gt is equal to the mass of a one-kilometre-sided cube of water, or about 400,000 Olympic swimming pools.
It gets worse: the study, published in Nature, also found that the rate of ice loss is accelerating by an average of 48 Gt per year each decade.
The paper highlights that this ice loss accounts for a significant amount (21%) of global sea level rise. As the research team warns, “200 million people live on land that is predicted to fall below the high-tide lines of rising sea levels by the end of the century.”
The researchers analysed archives of high-resolution satellite and aerial images of 217,175 glaciers – 97.4% of the world’s total.
As Lauren Vargo, from the Antarctic Research Centre at the Victoria University of Wellington in New Zealand, explains, this isn’t the first study to calculate global glacier mass from satellite observations, but the results are important largely because the authors were able to calculate global glacier mass change much more precisely than in previous studies.
The latest IPCC report, for example, estimated the global mass loss of glaciers at 278 Gt per year, but with an enormous uncertainty of ± 226 Gt. In contrast, this new study finds a comparable estimate (267 Gt per year) but reduces the uncertainty to just ± 17 Gt per year.
“Being able to more precisely measure how glaciers are currently changing is important for creating policy and management around impacts including changes in hydrology, rising sea level and increasing natural hazards,” says Vargo.
“These more precise measurements are also important because they enable us to do a better job of modelling how glaciers will continue to change in the future and then better predict the impacts of those future changes.”