Earth's healing ozone layer may have unexpected effects on the climate of the Southern Hemisphere, researchers predict (Science 2008, 320, 1486). An international team headed by Columbia University's Seok-Woo Son used the Chemistry Climate Model Validation (CCMVal) system to forecast that the Westerly Jet, a wind current that races around the Southern Hemisphere during the summer, may ultimately slow down as the ozone layer continues to regenerate through the middle of this century. The CCMVal model predicts that deceleration of the Westerly Jet would lead to an increase in ocean surface temperatures and a decrease in sea ice, as well as altered ocean circulation patterns. This scenario runs counter to the general improvement in climate conditions predicted by the most recent assessment issued by the Intergovernmental Panel on Climate Change (IPCC). Son and coworkers attribute the significant differences between the CCMVal and IPCC models to the "fully interactive stratospheric chemistry" of CCMVal, which permits it to account for how increasing ozone levels could affect the atmosphere. The study demonstrates that developing more accurate computer models is essential in predicting and understanding the outcomes of complicated phenomena such as climate change, the researchers note.