Anthropogenic influence on recent circulation-driven Antarctic sea-ice changes

• Published in: Geophysical Research Letters
• Main Authors: Haumann, F., Notz, D., Schmidt, H.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2014
• Subjects: Antarctic; Antarc*; Sea ice
• Online Access: http://hdl.handle.net/11858/00-001M-0000-0024-478D-4; http://hdl.handle.net/11858/00-001M-0000-002D-E87A-A

Observations reveal an increase of Antarctic sea ice over the past three decades, yet global climate models tend to simulate a sea-ice decrease for that period. Here, we combine observations with model experiments (MPI-ESM) to investigate causes for this discrepancy and for the observed sea-ice increase. Based on observations and atmospheric reanalysis, we show that on multi-decadal time scales Antarctic sea-ice changes are linked to intensified meridional winds that are caused by a zonally asymmetric lowering of the high-latitude surface pressure. In our simulations, this surface-pressure lowering is a response to a combination of anthropogenic stratospheric ozone depletion and greenhouse gas increase. Combining these two lines of argument, we infer a possible anthropogenic influence on the observed sea-ice changes. However, similar to other models, MPI-ESM simulates a surface-pressure response that is rather zonally symmetric, which explains why the simulated sea-ice response differs from observations.