This new paper by Joseph D`Aleo and Anthony Watts two of America`s most respected and experienced meteorologists can be found on the SPPI (www.scienceandpublicpolicy.org)web site, click on "papers". This 200 page work details the manipulation, exaggeration and deception behind much of the global warming movement today. They conclude that the instrument temperature data for the pre satellite era 1850-1980 has been so widely systematically and uni-directionally tampered with that it cannot be credibly asserted there has been any significant global warming in the 20th century. Indeed this squares with the recent comment by Dr Phil Jones of CRU at the University of East Anglia in a recent BBC interview in which he said "his surface temperature data are in such disarray they probably cannot be verified or replicated".
They note that global terrestrial temperature data are compromised because more than three quarters of the 6000 stations that once reported are no longer being used in data trend analysis. The NOAA(National Oceanic and Atmospheric Administration) stations lost around the world have a bias toward higher latitude,higher altitude and rural locations, all of which have a tendency to be cooler.
They found that all terrestrial surface temperature databases exhibit signs of urban heat pollution and post measurement adjustments that render them unreliable for determining long term temperature trends.
Contamination by urbanization, changes in land use, improper siting and inadequately calibrated instrument upgrades further increased uncertainty. Satellite temperature readings from 1980 onwards show an increasing divergence from the terrestrial stations consistent with evidence of a warm bias in the surface temperature record. Dr Wilson Flood has an analysis of the CET(Central England Temperature) record, the longest in the world which is included in this paper. He finds the average summer 18th century temperature to be 15.46degC compared with 15.35degC for the 20th century! In other words UK summers in the 20th century have been cooler than those of two centuries previously.! So much for global warming!