From the AGU Weekly Journal Highlights
While sea ice extent has declined dramatically in the Arctic in recent years, it has increased slightly in the Antarctic. Some scientists have suggested that increased Antarctic sea ice extent can be explained by the ozone hole over Antarctica. Previous simulations have indicated that the ozone hole induces a large change in atmospheric circulation in austral summer and that this change in circulation could contribute to the changing Antarctic sea extent.
To learn more, Sigmond and Fyfe use a climate model, forced by monthly varying observed stratospheric ozone changes from 1979 to 2005, to simulate the effects of stratospheric ozone depletion on Antarctic sea ice extent.
Contrary to predictions of previous studies, their model finds that ozone depletion would lead to a year-round decrease in Antarctic sea ice extent rather than the increase that was observed. The results suggest that processes other than ozone depletion must be causing the observed increase in Antarctic sea ice extent. It remains unclear why Southern Hemisphere sea ice trends differ so greatly from Northern Hemisphere trends.
Title: Has the ozone hole contributed to increased Antarctic sea ice extent?
Authors: M. Sigmond: Department of Physics, University of Toronto, Toronto, Ontario, Canada;
J. C. Fyfe: Canadian Centre for Climate Modelling and Analysis, Environment Canada, Victoria, British Columbia, Canada.
Source: Geophysical Research Letters, doi:10.1029/2010GL044301, 2010 http://dx.doi.org/10.1029/2010GL044301
GEOPHYSICAL RESEARCH LETTERS, VOL. 37, L18502, 5 PP., 2010
Has the ozone hole contributed to increased Antarctic sea ice extent?
Department of Physics, University of Toronto, Toronto, Ontario, Canada
J. C. Fyfe
Canadian Centre for Climate Modelling and Analysis, Environment Canada, Victoria, British Columbia, Canada
Since the 1970s sea ice extent has decreased dramatically in the Northern Hemisphere and increased slightly in the Southern Hemisphere, a difference that is potentially explained by ozone depletion in the Southern Hemisphere stratosphere. In this study we consider the impact of stratospheric ozone depletion on Antarctic sea ice extent using a climate model forced with observed stratospheric ozone depletion from 1979 to 2005. Contrary to expectations, our model simulates a year-round decrease in Antarctic sea ice due to stratospheric ozone depletion. The largest percentage sea ice decrease in our model occurs in the austral summer near the coast of Antarctica, due to a mechanism involving offshore Ekman sea ice transport. The largest absolute decrease is simulated in the austral winter away from the coast of Antarctica, in response to an ocean warming that is consistent with a poleward shift of the large-scale pattern of sea surface temperature. Our model results strongly suggest that processes not linked to stratospheric ozone depletion must be invoked to explain the observed increase in Antarctic sea ice extent.
Received 11 June 2010; accepted 5 August 2010; published 29 September 2010.
Citation: Sigmond, M., and J. C. Fyfe (2010), Has the ozone hole contributed to increased Antarctic sea ice extent?, Geophys. Res. Lett., 37, L18502, doi:10.1029/2010GL044301.