Future climate change in the southern hemisphere will likely be dominated by two competing effects: the recovery of the ozone hole over Antarctica and increasing greenhouse gases. Both of these influence the Southern Annular Mode (SAM), a southern hemisphere wide pattern of climate variability that influences aspects of climate from temperature and precipitation to oceanic circulation and Southern Ocean carbon uptake. However, different models give different answers as to whether greenhouse gases or ozone will have a greater impact on SAM trends over the coming decades. New research led by DOE scientists at the National Center for Atmospheric Research (NCAR) examines the future response of the SAM in two NCAR models. Both models suggest that recent positive summertime trends in SAM will reverse sign over the coming decades as the ozone hole recovers. Their results also suggest that the response to greenhouse warming will play a large role in modifying the strength of the response. Understanding the mechanisms behind the various model results is an important step towards narrowing uncertainty in future climate projections.
Reference: Arblaster, J.M., G.A. Meehl, and D.J. Karoly. 2011. “Future Climate Change in the Southern Hemisphere: Competing Effects of Ozone and Greenhouse Gases,” Geophysical Research Letters 38, L02701, doi:10.1029/2010GL045384.
Contact: Renu Joseph, SC-23.1, (301) 903-9237, Dorothy Koch, SC-23.1, (301) 903-0105
SC-23.1 Climate and Environmental Sciences Division, BER
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