TABLE OF CONTENTS Both adherents and critics of the man-made global warming paradigm attach importance to the notion of global mean temperatures . They disagree about the accuracy of the measurements, about the relevance of the choice between surface measurements and balloon/satellite measurements, about the urban heat island effect, about the unevenness of the current distribution of measuring stations over the surface of the earth etc., but they both acknowledge the usefulness of the notion of worldwide mean temperatures and its variations as a proxy for climate change. In that sense they share common ground. Enter a new breed of climate sceptics, two Canadian scientists, Christopher Essex and Ross McKitrick, who seem to be bent on destroying this common ground, even to the point that there will be no ground at all left on which to disagree. Let us see what it is all about.
We recall that the idea of a possible man-made global warming is based on the observation that the carbon dioxide (CO 2) content of the atmosphere, measured on Mauna Loa (the largest volcano on Earth which makes half of the area of the Island of Hawaii), had risen during the twentieth century from approximately 285 to 365 ppm (parts per million by volume). This could be expected to increase the absorption of outgoing heat radiation (from the earth s surface to space). The resulting accumulation of energy might give rise to an increase of the average surface temperature of the earth. Whether this actually...
