'Half-a-degree of warming boosted extreme weather'

Comparing two 20-year periods -- 1960-79 and 1991-2010 -- between which average global temperatures jumped 0.5 C (0.9 F), scientists found that the hottest summer temperatures increased by more than 1 degree C across a quarter of Earth's land areas, while the coldest winter temperatures warmed by more then 2.5 degree C.