One way adjustments: The Latest Alteration to the U.S. Climate Record .
On Thursday, March 13, 2014, the U.S. National Climactic Data Center switched to gridded GHCN-D data sets it uses to report long term temperature trends – with a resulting dramatic change in the official U.S. climate record. As seems to always happen when somebody modifies the temperature record, the new version of the record shows a significantly stronger warming trend than the unmodified or, in this case, discarded version.
The new dataset, called “nClimDiv,” shows the per decade warming trend from 1895 through 2012 for the contiguous United States to be 0.135 degrees Fahrenheit. The formerly used dataset, called “Drd964x,” shows the per decade warming trend over the same period to be substantially less – only 0.088 degrees. Which is closer to the truth?
As will be illustrated below in the side by side comparison graphs, the increase in the warming trend in the new data set is largely the consequence of significantly lowering the temperature record in the earlier part of the century, thereby creating a greater “warming” trend.
This particular manipulation has a long history. For an outstanding account of temperature record alterations, tampering, modifications and mutilations across the globe, see: