Study sees changing intensity of storms from warming

Morgan Bettex in the MIT News Office: Weather systems in the Southern and Northern hemispheres will respond differently to global warming, according to an MIT atmospheric scientist’s analysis that suggests the warming of the planet will affect the availability of energy to fuel extratropical storms, or large-scale weather systems that occur at Earth’s middle latitudes. The resulting changes will depend on the hemisphere and season, the study found.
More intense storms will occur in the Southern Hemisphere throughout the year, whereas in the Northern Hemisphere, the change in storminess will depend on the season — with more intense storms occurring in the winter and weaker storms in the summer. The responses are different because even though the atmosphere will get warmer and more humid due to global warming, not all of the increased energy of the atmosphere will be available to power extratropical storms. It turns out that the changes in available energy depend on the hemisphere and season, according to the study, published Monday in the Proceedings of the National Academy of Sciences.
Fewer extratropical storms during the summer in the Northern Hemisphere could lead to increased air pollution, as “there would be less movement of air to prevent the buildup of pollutants in the atmosphere,” says author Paul O’Gorman, the Victor P. Starr Career Development Assistant Professor of Atmospheric Science in MIT’s Department of Earth, Atmospheric and Planetary Sciences. Likewise, stronger storms year-round in the Southern Hemisphere would lead to stronger winds over the Antarctic Ocean, which would impact ocean circulation. Because the ocean circulation redistributes heat throughout the world’s oceans, any change could impact the global climate.
…Although the analysis suggests that global warming will result in weaker Northern Hemisphere storms during the summer, O’Gorman says that it’s difficult to determine the degree to which those storms will weaken. That depends on the interaction between the atmosphere and the oceans, and for the Northern Hemisphere, this interaction is linked to how quickly the Arctic Ocean ice disappears. Unfortunately, climate scientists don’t yet know the long-term rate of melting…

Storm approaching Anna Bay in New South Wales, Australia, shot by Warrenlead69, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported