Nice story over at Newscientist.com about a new study by David C. Lund, Jean Lynch-Stieglitz, and William B. Curry in Nature that undercuts the “where’s the little ice age?” argument against Mann’s Hockey Stick graph:
The “hockey stick” graph, which shows a rapid rise in world temperatures over recent decades, has been both poster child for the dangers of human-induced global warming and prime target for climate change sceptics. They cite an anomaly in the graph – it does not record a dip in temperature between 1200 and 1850 – as reason to ditch the whole thing. Now new data may help explain why the graph does not record the “little ice age”.
Ocean currents in the North Atlantic, dominated by the Gulf Stream, usually keep winter temperatures in western Europe mild by carrying warm water north from the tropics towards Europe and heating the westerly winds traveling from North America. Climate scientists have suspected that a weak Gulf Stream may have caused the little ice age, but until now there has been no direct evidence for this theory.