It seems whenever I see an attempt to claim AGW has stopped, it's bolstered with a WfT graph of
HadCRUT data that shows a downward trend between arbitrary dates in the last 11 years.
While reviewing the bounty of solar and climate information found at the Global Warming Science site, we found the adjacent chart (this is the «C3» revised version using annual
HadCRUT global temperatures instead of monthly).
@michaelsweet, thanks, can't blame a layperson for
using hadcrut in this instance, and I'm waiting for his response on the as - yet - unrealised warming.
Using monthly data from 1900 to April 2009
on Hadcrut global temp (not N hemisphere, which data I do not have handy): 1.
Analysis by European Centre for Medium - Range Weather Forecasts (ECMWF) and NASA GISS (Hansen 2006) find that the areas omitted
by HadCRUT are some of the fastest warming regions in the world.
Below is a figure showing a similar comparison
between HadCRUT 3v and GISTEMP (from NASA / GISS).
If there is indeed a fairly close correlation between the US surface temps and US satellite temps, then that would show just how «whacked out» the GISS and
Hadcrut temps could be.
Base period 1961 - 1990 is used for comparison with published
HadCRUT analyses in Figures 3 and 4.)
Maybe there is a hidden meaning of HadCRUT4
= HadCRUT with $ not capped)
The full implications will be apparent
when HadCRUT release revised data.
You will note the noise on the residuals (blue trace) still carries a signal of about half the amplitude of the original
HadCRUT signal, so the residuals are not just noise as had been alleged.
The figures came from a database
called Hadcrut 4 and were issued by the Met Office and the Climatic Research Unit (CRU) at East Anglia University.
How much the temperature changes in the years before and after 1945, we'll have to wait and see when
HadCRUT release the revised data.
I like what C&W have done over all, but I do think they deserve a bit of criticism for quoting the effect of their results as a multiplicative factor, which is misleading because the actual magnitude of the correction is indisputably small, and for quite brazenly cherry picking an extreme interval to compare the difference between their result and the original
HadCRUT algorithm.
Thus the method used above by Gavin is right and it is no surprise that
HadCRUT finds similar uncertainties.
Will be interesting to see the
revised HadCRUT data - both for the 1940's and apparently the past decade.