GISS Global Sea and Land Surface Temperatures as they were reported in 1981, 1995, 2003 and today. The line are 5 years averages, or, more accurate, 60 months averages.
- 1981: Hansen e.a (image copy)
- 1995: Steve Mcintyre (monthly anomaly)
- 2003: Internet Archive (monthly anomaly)
- 2014: current GISS site (monthly anomaly)
Baselines: for 1981 the baseline is the period of 1880-1980. For others it is 1951-1980. Can be found in the documents.
Conclusion: this diagram shows that Steven Goddard erred here.
In this picture we have plotted the 60-months moving average against a background of the monthly averages.
If we want to view this moving average as an indication of the current anomaly, then we have to move it to the right, otherwise the moving averages of the “current anomaly” would contain future values.
Normally the hiatus is illustrated by drawing a straight line from around 1997, and – as this line is almost horizontal -it is used as proof that the warming has stalled. However, it is not so simple. In 1997-1998 the global temperatures suddenly rose to new levels, and from that new level indeed the temperatures stayed more or less the same(*).
Look at the dots in the upper right corner. These higher values are all in a sudden common after 1998, whereas before 1997 there are none of them except for a couple of outliers. After 1998 more than 50% of all months were warmer than any month before (except those 2 outliers).
What we witness is a steep increase of 0.18 degree C in 5 years time followed by a stationary period. You cannot call that a stagnation IMHO. The next blog item gives a more detailed analysis.
(*) Using only values after 1997 in an autocorrelated series is a statistical blunder.