Projections of glacier disappearance in 2100 according to two scenarios of global average temperature increase. Background, Upsala glacier, Patagonia © Etienne Berthier / CNRS / LEGOSHow will our glaciers evolve during the 21st century - In a new study to be published on January 5 in the journal Science, an international team 1 , including scientists from CNRS and the University Paul Sabatier Toulouse III, reveals a loss of glacier mass greater than previously projected. According to their work, this loss increases by 14% to 23% compared to previous projections, including those used in the last IPCC report. The majority of our planet’s glaciers are small, less than 1 km2, and they are the most affected by this loss of mass. Thus, according to the scenario with a limitation of the temperature rise to 1.5°C, 49% of the world’s glaciers, including all the small ones, are nevertheless expected to disappear by 2100, causing a 9 cm rise in sea level. In this hypothesis, the largest glaciers are also impacted, without disappearing. If the temperature increase reaches 4°C, both small and large glaciers would be affected and 80% of glaciers would disappear, with a sea level rise of 15.4 cm. To arrive at these results, the scientists relied on observations from a study that quantified widespread and accelerated mass loss of the world’s glaciers between 2000 and 2019. This previous information was used to calibrate the mathematical model, designed in this new publication, one by one for the 200,000 glaciers on Earth. In addition, the model now takes into account previously unrepresented processes, such as mass losses related to iceberg calving and the effect of a debris cover on the glacier surface. The mass losses of the largest glaciers, such as those in Alaska, the Canadian Arctic or around Antarctica, which are key to future sea level rise, could still be limited with the implementation of measures to contain temperature increases.
1 In France, this research involved scientists from the Laboratoire d’étude en géophysique et océanographie spatiales (CNRS/CNES/IRD/Université Paul Sabatier Toulouse III)
Global glacier in the 21st century: Every increase in temperature matters, Rounce , D. R., Hock, R., Maussion, F., Hugonnet, R., Kochtitzky, W., Huss, M., Berthier, E., Brinkerhoff, D. J., Compagno, L, Farinotti, D., Menounos, B., and McNabb, R. W.: Global glacier change in the 21st century: Every increase in temperature matters, Science, 6 January 2023, DOI :https://doi.org/10.1126/science.abo1324, 2023
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