Observed Arctic sea-ice loss directly follows anthropogenic CO2 emission.
Arctic sea ice is retreating rapidly, raising prospects of a future ice-free Arctic Ocean during summer. Because climate-model simulations of the sea-ice loss differ substantially, we used a robust linear relationship between monthly-mean September sea-ice area and cumulative carbon dioxide (CO2) emissions to infer the future evolution of Arctic summer sea ice directly from the observational record. The observed linear relationship implies a sustained loss of 3 ± 0.3 square meters of September sea-ice area per metric ton of CO2emission. On the basis of this sensitivity, Arctic sea ice will be lost throughout September for an additional 1000 gigatons of CO2emissions. Most models show a lower sensitivity, which is possibly linked to an underestimation of the modeled increase in incoming longwave radiation and of the modeled transient climate response.
Max Planck Institute for Meteorology, Hamburg, Germany. dirk.notz@mpimet.mpg.de.
Dirk
D
Notz
National Snow and Ice Data Center, Boulder, CO, USA.|University College, London, UK.
Julienne
J
Stroeve
D001110:Arctic Regions; D002245:Carbon Dioxide / Q000032:analysis*; D003198:Computer Simulation; D057232:Global Warming; D017752:Greenhouse Effect; D006801:Humans; D046448:Ice Cover; D008962:Models, Theoretical; D012621:Seasons
D002245:Carbon Dioxide