This post is a very delayed issue of a conversation a year ago (a lot happened this year so it stayed in draft, seemed a waste not to publish it).
During my conversation on twitter with Paul Carfoot another statement popped up, this time from ‘Friends of Science‘, who describe themselves as “A group of earth, atmospheric, solar scientists and engineers” – Warren Blair is ‘President’ but they are sketchy on who they are. More here & here.
So lets take a look…..
The 1990 IPCC report ‘acknowledges’ MWP/MCA (they call the MWP the Medieval Climate Anomaly) but does not acknowledge that it was ‘as warm as today’. The red arrows above have of course been added by someone else. From FoS;
From the IPCC;
So I’ve marked the dotted line as c1900 and the vertical scale on the right (please let me know if this is incorrect).
On a later page (pg. 254) of the same 1990 IPCC report are the details from the last 130 or so years to 1990, split into north & south hemispheres.
So that was the limit of knowledge in 1990, but to quote this report as proof that there has been ‘800 years of cooling’ is surely a bit simplistic when we know an awful lot more about global temperatures now, some 26 years later. Would you use data this old to ‘prove’ your theory of cooling? Only if you are a fake sceptic perhaps?
Some work suggests that the origins of the graph are actually from 1965, a whole 51 years ago. And based on data from just Central England, not global at all.
Comparison of MBH99 40-year average from proxy records, as used in IPCC TAR 2001 (blue), with IPCC 1990 schematic Figure 7.1.c (red) [based on Lamb 1965 extrapolating from central England temperatures and other historical records]; central England temperatures to 2007 shown from Jones et al. 2009 (green dashed line). Also shown, Moberg et al. 2005 low frequency signal (black).
From the 5th IPCC report (2013), showing that current knowledge is vast and that temperatures have climbed well above the Medieval Warming Period.
Not exactly ‘800 years of cooling’, is it?