Hilarious! The new British climate record (HadCRUT4) reinforces how FLAT average temperatures have been in the last 12 years

The differences between years are only in hundredths of one degree! How trivial can you get?

The media have almost unanimously said that HadCRUT4 now makes 2010 the hottest year. But what HadCRUT4 actually shows is that 2010 ties with 2005 for the hottest year and a trivial 0.01 deg C above 1998. Given the errors (0.1 deg C or ten times the difference being quoted) the only scientifically respectable way to describe the warmest years would be to say that 1998, 2005 and 2010 all tied, but that would have perhaps been a little to inconvenient. I note that NasaGiss, and here, faced a similar problem but chose to follow the respectable route in not calling a record if a year has a temperature difference of only 0.01 deg C.

In fact a better way to summarise HadCRUT4 is that one cannot rank with confidence the top eight years (ranging from 0.53 to 0.48 deg C) so they should all be declared statistically indistinguishable.

Bad Practice

It is regrettable, and in my view poor form, to release the HadCRUT4 top ten years and not simultaneously release the complete dataset so that a more detailed look can be made at the time the media are compiling their stories based on the Met Office press release. Not releasing the full dataset could lead to accusations of ‘spinning’ the data. The HadCRUT4 complete data is said to be available in a few days. There is no reason why the Met Office’s press release of the 19th March could not have been held for a few days to coincide with the full data. In most other scientific disciplines this is standard practice.

Some parts of the media are claiming that HadCRUT4 shows an increased warming since 1998 of 0.11 deg C (said to be 0.04 deg C more). However, until the full data is available it will not be possible to look at this figure in more detail though looking at the data that is available I don’t think that figure will stand up.

Also mentioned in the Met Office press release is the global warming ‘signal’ seen since 1900, which they say is 0.75 deg C. Of course that ‘signal’ is not homogenous as we have discussed because it includes the periods not influenced by mankind and those said to be under his influence.

Overall the new HadCRUT4 dataset does not seem to change anything. It even seems to emphasise the lack of warming in the past 10-15 years more than HadCRUT3 did. Although we do not yet have HadCRUT4 data for 2008 it is obvious that HadCRUT4 has less variance in this short period. HadCRUT3 had a range of 0.12 between the top ten warmest years with a fairly even spread. HadCRUT4 has the top three years separated by 0.01 and years 4 -8 also separated by 0.01 deg C, in fact years 4,5,6,7 are identical numerically.

More HERE (See the original for links, graphics etc.)

Posted by John J. Ray (M.A.; Ph.D.).