The Antarctic ice sheet does not behave as one single tipping element, but as a set of interacting basins with different critical thresholds. This is the finding of a new study by the Potsdam Institute for Climate Impact Research (PIK) and the Max Planck Institute of Geoanthropology (MPI-GEA). With today’s warming, about 40 percent of the ice stored in West Antarctica may already be committed to long-term loss, while parts of East Antarctica could cross thresholds at moderate levels of warming between 2 to 3°C compared to pre-industrial levels, contributing significantly to global long-term sea-level rise.
“It’s not one single threshold we need to watch in Antarctica – it’s a sequence”, explains Ricarda Winkelmann, MPI-GEA director and PIK scientist, and lead author of the study published in Nature Climate Change. “In fact, we find that ice loss in some Antarctic basins unfolds rather gradually with warming, whereas other basins are characterized by a tipping point, beyond which the loss of ice accelerates disproportionally to the warming and can be irreversible over centuries to millennia.”
“The Antarctic ice sheet took millions of years to form, but with global emissions continuously rising, we may lock it onto a path of long-term loss within the coming decades” states Torsten Albrecht, MPI-GEA and PIK scientist and co-author of the study
Map of Antarctica showing the 18 ice-sheet drainage basins as used in this analysis (thin black lines; ref. 84) as well as their sea-level potential (in metres sea-level equivalent, m SLE), illustrated by the size of the respective circles. Nested circles show the critical temperature levels at which the strongest ice loss occurs in the model simulations (circle colour) as well as the fraction of ice volume lost in the long term upon transgression of those thresholds with respect to the initial ice volume of the basin (circle size). Background shading shows the bedrock topography (tan–brown above sea level, white–blue below sea level); ice shelves are highlighted by grey shading. AP, Antarctic Peninsula. Observed Antarctic topography from the Bedmap2 dataset (ref. 95).
Text taken from Potsdam Institute for Climate Impact Research, Latest News page on New study identifies sequence of critical thresholds for Antarctic ice basins.
Fig. 1: Risk map of Antarctic ice catchment basins from Mapping tipping risks from Antarctic ice basins under global warming | Nature Climate Change