
In 2001, the U.N. Intergovernmental Panel on Climate Change (IPCC) featured a graph of Northern Hemisphere temperature history from a 1999 study by Profs. Michael Mann, Raymond Bradley, and Malcolm Hughes. Because of its shape, the graph became known as the “hockey stick.” From A.D. 1,000 to about 1915, the graph depicts a gradual decline in Northern Hemisphere temperatures (the hockey stick [...]