I was working on another project related to the CRU emails and came across this email from Dr.Phil Jones. I was stunned, not only because he was dissing another dataset, but mostly because that dissing hit many of the points about problems with the NASA GISS products we’ve covered here on WUWT and at Climate Audit.
Here’s the email with my highlights added. Email addresses have been partially redacted.
The original email can be seen at this link:
Here’s the thing, we’ve seen the problems with CRU’s temperature series in the code already. If Dr. Jones is aware of those problems, and he thinks GISS is inferior, well then, wow, just how bad is GISS?
I thought this statement was quite telling:
Their non-use of a base period (GISS using something very odd and NCDC first differences) means they can use
very short series that we can’t (as they don’t have base periods) but with short series it is impossible to assess for homogeneity.
One thing about GISS that has bothered a lot of people – the base period they use for calculating temperature anomaly is for 1951-1980. See it listed here on the GISTEMP page. No other data sets use that period. Critics (including myself) have said that by using that period, it makes this graph’s trend look steeper than it would if the current 30 year period was used.
In the past couple of years we’ve seen two significant errors with NASA GISS that had to be corrected after they were discovered through the work done here at at WUWT and Climate audit. Public errors have not been found in CRU products during that time, because the data an code have been withheld.
To the credit of NASA GISS, they have been more transparent than CRU on data, stations used, and code.
Here are some of the relevant posts on WUWT where we address issues found with the NASA GISS temperature products: