On 26/03/2013 18:22, djc wrote:
On 26/03/13 13:25, polygonum wrote:

Considering how long we have had people recording the weather (Fitzroy
systematically - and many, many others with varying accuracy and
completeness over at least many centuries), I fail to understand why
they keep referring to "since records began" as referring to a period
within my own lifetime. Have they thrown all the old records out? Have
they decided that the standards to which they were made are not
compatible? If they have done that, then they need to be much more
forthcoming about what they actually mean.

It is always difficult to reconcile any 'long series' or records, in any
subject. What instruments were used, how were they calibrated,
conversion factors, where, in what circumstances, language, terminology,
reliability of witnesses, discontinuity of records etc..

Which, IIRC was the argument NASA put forward for adjusting figures that
showed rather inconveniently high temperatures in the early 20th century.

Colin Bignell