Spotlights
281 - Breaking the 'Hockey Stick': Global Warming's Latest Brawl

March 01, 2006

Evidence from throughout the world shows that the planet was relatively warm 1,000 years ago during the Medieval Warm Period and relatively cold 500 years ago during the Little Ice Age. When the 1°C (1.8°F) of global warming of the past 100 years is considered in the context of climate variability of the last 1,000 years, the recent warming looks quite natural and nothing out of the ordinary. In 2001, the United Nations Intergovernmental Panel on Climate Change prominently featured an important graph of northern hemispheric temperatures over the past 1,000 years, and the plot resembled a hockey stick. This same graph was recently highlighted in testimony to the North Carolina Legislative Commission on Climate Change. In this graph, the Medieval Warm Period and the Little Ice Age disappeared, and after 900 years of nearly steady temperatures, warming dominates the most recent 100 years. The new “hockey stick” depiction makes the recent warming look highly unnatural, thereby lending credence to the argument that human activities are the driving force behind global warming. The fights over the hockey stick have been among the most vicious in the two decades of heated debate over global warming.

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