Here the trend is 0.17 C / decade, which is the fit to
adjusted GISTEMP.
A plot of land - only unadjusted and UHI -
adjusted GISTemp data would show a more discernible difference (but still not huge).
Using the Foster and Rahmstorf
adjusted GISTEMP trend of 0.17 C / decade, we get a temperature increase over three decades of 0.51 C, with short term fluctuations eliminated.
Not exact matches
(Note: For strict validity the anomaly baseline period of the
GISTEMP map series was first
adjusted to match the CRU data.)
February 14, 2015: UK Press reports in January 2015 erroneously claimed that differences between the raw GHCNv2 station data (archived here) and the current final
GISTEMP adjusted data were due to unjustified positive adjustments made in the
GISTEMP analysis.
GISTemp for example seeks to identify such urban stations and then
adjust them so that the urban station's long - term trend is brought into line with adjacent rural stations.
The effect is illustrated in Figure 1: The first graph is from the NASA
GISTEMP temperature record, while the second uses the
adjusted data of Foster and Rahmstorf (2011) which removes some of the short term variations from the signal.
Certainly, over 1979 - 2015 both the
adjusted ERA - interim and HadCRUT4v4 datasets showed a slightly higher trend in global temperature (of respectively 0.166 and 0.165 °C / decade) than did
GISTEMP (0.162 °C / decade).
Can you also explain to them the ways in which
GISTEMP is
adjusted, just to get it cleared up?
A. UK media reports in January 2015 erroneously claimed that differences between the raw GHCN v2 station data (archived here) and the current final
GISTEMP adjusted data were due to unjustified positive adjustments made in the
GISTEMP analysis.