GISS & The Tampered ERSST Dataset
By Paul Homewood
We are all doubtlessly familiar with Thomas Karl’s infamous “pausebuster” paper from last June. It achieved its aim of getting rid of the inconvenient pause largely by massive tampering with sea surface temperatures in NOAA’s Extended Reconstructed Sea Surface Temperature (ERSST) dataset.
The effect of their adjustments is shown on the GISS graph, published last July:
Note the veritable hockey stick starting in 1998. WUWT has already gone into great detail to discredit the whole exercise, so I don’t want to revisit that.
But there is an interesting background to ERSST which may shed light on motivations.
ERSST is not the only SST dataset, there are also Reynold’s OISST and the Met Office’s HADISST. In January 2013, GISS made this seemingly innocuous statement:
I made a bit of a fuss at the time, because the change added about 0.03C to the latest global temperatures, a small change, but, as we know, just one of series of small changes all in the same direction.
When I emailed Reto Ruedy of GISS (who I must say is always helpful), he replied:
Last week Dr. Hansen decided to switch to ERSST for the ocean temperatures rather than using our Hadley/Reynolds combination. We will write a note concerning that change with an analysis of its effect.
However, since the margin of error for these estimates even for the most recent years is about +-0.05 C, differences of the order 0.03 C are well within that margin of error, hence not significant.
I personally like the switch, since now all our basic data (land and ocean) come from the same source which simplifies the description of what we are doing.
Thank you for your interest,
It all sounded very innocent at the time, although maention of “Dr Hansen deciding to switch” should perhaps have raised alarm bells. It is now becoming clear that plans were already afoot to get rid of that pesky pause. NOAA, of course, were already using ERSST. How much more convenient it would be for GISS to switch to the same dataset.