Environment Counts | Climates of Southern and Northern Hemispheres appear to act independently :

Recent instrumental data have shown a remarkable degree of asynchronicity between Northern Hemisphere and Southern Hemisphere temperature. This article reports a new reconstruction of annually resolved temperature variations over the past thousand years for the Southern Hemisphere based on a network of terrestrial and oceanic palaeoclimate proxy records. Analysis of the Southern Hemisphere data together with an independent Northern Hemisphere temperature reconstruction reveals an extended cold period (1594–1677) in both hemispheres but no globally synchronous warm period during the pre-industrial (1000–1850) era. The current (post-1974) warm phase is the only period of the past millennium where both hemispheres have experienced simultaneous warm extremes. Nature Climate Change 4,362–367(2014)doi:10.1038/nclimate2174