Aug 13, 2018

Attribution of Arctic Sea Ice Decline from 1953 to 2012 to Influences from Natural, Greenhouse Gas, and Anthropogenic Aerosol Forcing

by
B.L. Mueller
,
Journal of Climate
  • Presents results from a climate change detection and attribution study on the decline of Arctic sea ice extent in September for the 1953–2012 period
  • Looks at three independently derived observational datasets and simulations for this period from multiple climate models to attribute observed changes in the sea ice extent to known climate forcings
  • Directs attention to the combined cooling effect from other anthropogenic forcing agents (mainly aerosols), which has potentially masked a fraction of greenhouse gas–induced Arctic sea ice decline
  • States that the presented detection and attribution framework consists of a regression model, namely, regularized optimal fingerprinting, where observations are regressed onto model-simulated climate response patterns (i.e., fingerprints)
  • Shows that fingerprints from greenhouse gas, natural, and other anthropogenic forcings are detected in the three observed records of Arctic sea ice extent
  • Beyond that, the findings indicate that for the 1953–2012 period roughly 23% of the greenhouse gas–induced negative sea ice trend has been offset by a weak positive sea ice trend attributable to other anthropogenic forcing
  • Shows that the detection and attribution results remain robust in the presence of emerging nonstationary internal climate variability acting upon sea ice using a perfect model experiment and data from two large ensembles of climate simulations