I am mobile so I apologize for the brevity of this thread. A new study by Foster and Rahmstorf removes all natural variabilities from all of the main temperarure datasets to reveal the "true" global warming signal. The revealed global warming signal is remarkably linear with a constant rate and with remarkable agreement between the data sets. Worth a look. The below link is an overview but contains a link to the actual paper. http://tamino.wordpress.com/2011/12/06/the-real-global-warming-signa