The Northern Hemisphere is warming more quickly than the Southern Hemisphere thanks to the uneven distribution of land and sea around the globe, a study confirms.

Land masses warm more quickly than the ocean — in part because more heat is required to raise the temperature of water than that of land, and in part owing to the cooling effects of sea surface evaporation. Yangyang Xu and Veerabhadran Ramanathan of the Scripps Institution of Oceanography in La Jolla, California, used climate simulations to confirm that these effects can explain the global pattern of temperature change seen during periods of warming — in 1910–40 and 1975–2005 — as well as during a cooling period in 1940–75. The climate-model runs predict drastic changes in rainfall, including intense droughts in Africa, Western North America, the Amazon and Australia, and a boost to the Indian monsoon.

Geophys. Res. Lett. http://dx.doi.org/10.1029/2012GL052116 (2012)