Here is a blog from Strata-Sphere that discusses the incompetent error analyses (that is, uncertainty in instrument accuracy plus error introduced by the computations involved in creating measurements out of thin air) done by the Anthropogenic Global Warming (AGW) hypothesis advocates. The chart from NOAA showing the difference in raw temperature data and the "corrected" data is revealing. According to the raw data there was no warming during the 20th century; all of the warming came from the "corrections." Is this why they say the warming was "manmade."