Read here. Over 2,000 previous peer-reviewed studies are severely tainted with bad data from the often used ERA-40 Reanalysis regarding Arctic region temperature trends. Researchers Screen and Simmonds concluded that this dataset should no longer be relied on in future studies, which implies that many past studies indicating Arctic warming are robustly in error.
Essentially, group-think consensus science by "experts" at its worst: "Hey...why don't we all use the same computer output for every Arctic study." Brilliant.
"This study explicitly documents a discontinuity in the 40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40) that leads to significantly exaggerated warming in the Arctic mid- to lower troposphere, and demonstrates that the continuing use of ERA-40 to study Arctic temperature trends is problematic...Decadal or multidecadal Arctic temperature trends calculated over periods that include 1997 are highly inaccurate...It is shown that ERA-40 is poorly suited to studying Arctic temperature trends and their vertical profile, and conclusions based upon them must be viewed with extreme caution. Consequently, its future use for this purpose is discouraged."....."Such an error not only affects the Arctic troposphere, but necessarily must effect the entire northern hemisphere jet stream."[James A. Screen, Ian Simmonds 2011: Journal of Climate]
