Michael Mann’s team from Penn State University analysed data for the last 2,000 years, and concluded that Northern Hemisphere temperatures now are “anomalously warm.
Their work has been the subject of huge attack from the sceptics because the graph indicated that Northern Hemisphere temperatures had been roughly constant for 1,000 years before turning abruptly upwards in the industrial age (the curve in the hockey stick).
They have now reported in the Proceedings of the National Academy of Sciences that different analytical methods give the same result. In their latest study, Dr Mann’s group collated more than 1,200 proxy records – the majority from the Northern Hemisphere – and used different statistical methods to analyse their cumulative message.
“We used two different methods that are quite complementary in the assumptions they make about data, so that provides a test of the sensitivity of data to the methods used,” he told BBC News. Michael Mann’s conclusion is that far from being broken, “the hockey stick is alive and well”.
Tell that to the makers of the Great Global Warming Swindle…