J. Climate http://doi.org/khk (2013)
The Northern Hemisphere has warmed faster than the Southern Hemisphere in the past decades. Model simulations suggest that this trend can be attributed to inter-hemispheric differences in the impact of rising greenhouse gas concentrations on climate, and will continue throughout the twenty-first century.
Andrew Friedman of the University of California, Berkeley, and colleagues assessed inter-hemispheric differences in mean temperatures between 1880 and 2099, using observations and climate model simulations. Temperature differences between the two hemispheres remained fairly stable until 1980, at which point disproportionate warming in the Arctic and over the Northern Hemisphere land masses created a hemispheric asymmetry. The team suggests that anthropogenic aerosols masked this asymmetry until the implementation of air pollution regulations in the Northern Hemisphere in the 1970s.
The hemispheric asymmetry is projected to increase this century, which could cause the tropical atmospheric overturning circulation to weaken in the north and strengthen in the south. The researchers note that this could lead to a northward shift in tropical precipitation.