What would the implications be if the world’s historical temperature records had been manipulated in a way that results in a warming bias? A new report shows that this may, in fact, be the case. At the very best, the January 27, 2010 report, Surface Temperature Records: Policy Driven Deception?, suggests that global temperature databases are badly flawed and should not be used for the basis for making policy. Twelve “case studies in data manipulation” are included in the report.
There has clearly been some cyclical warming in recent decades, most notably 1979 to 1998. However, the global surface-station data is seriously compromised. First, there is a major station dropout and increase in missing data in stations that remained which occurred suddenly around 1990; about the time the global warming issue was being elevated to importance in political and environmental circles. A clear bias was found towards removing cooler higher elevation, higher latitude, and rural stations during this culling process though leaving their data in the base periods from which ‘averages’ and anomalies are computed.
The data also suffers contamination by urbanization and other local factors such as land-use/land-cover changes and improper siting. There are uncertainties in ocean temperatures; no small issue, as oceans cover 71% of the earth’s surface.
These factors all lead to significant uncertainty and a tendency for overestimation of century-scale temperature trends. A conclusion from all findings suggest that global data bases are seriously flawed and can no longer be trusted to assess climate trends or rankings or validate model forecasts. And, consequently, such surface data should be ignored for decision making.