From: wmc@unixa.nerc-keyworth.ac.uk (William Connolley)
Newsgroups: sci.environment
Subject: Medieval Warm Period? (was: Reply to Schloerer)
Date: 15 May 1995 17:27:50 GMT
Message-ID: <3p82um$j0l@kwuz.nerc-keyworth.ac.uk>

OK, so the subject is: was there a medieval warm period? 

First a little diversion:
In article iib@nntp.Stanford.EDU, moore@Hoover.Stanford.EDU (Tom Moore) writes:
>I personally disagree that the forcing mechanism is key. Warming is warming.
Dubious at best, IMHO

Now back to the MWP: TM posts, from [3]:
>"We come back to our original question: was there a 'Medieval Warm
>Period', and if so, where and when? Some of the evidence compiled here
>and in the twelve articles of this special volume suggests that the time 
>interval known as the *Medieval Warm Period* from the ninth to perhaps
>the mid-fifteenth century A.D. may have been associated with warmer
>conditions than those prevailing over most of the next five centuries 
>(including the twentieth century), a least during some seasons of the year
>and in some regions."

This, although stuffed full of qualifications, is intended to support the MWP.
But lets continue the quote a little bit further, shall we...

From Hughes+Diaz, Climatic Change, March 1994, pp:109-142
(emphasis mine)

Section 8, Concluding Remarks

We come back to our original question: was there a "Medieval Warm Period", 
and if so, where and when? Some of the evidence compiled here and in the 12 
articles of this special volume suggests that the time interval known as the MWP
from the ninth to perhaps the mid fifteenth century AD may have been
associated with warmer conditions than those prevailing over most of the next 5
centuries (including the 20 C), at least during some seasons of the year
in some regions.
[TM stops here]
It is obvious, however, that we have only, at best, a rough picture
of the climate of this epoch, and that much work remains to be done to portray
in greater detail the climatic essence of the 9th through 14th C.
In particular, the simplified representations of the course of global temp
variation over the last 1000 y reproduced in various technical and popular
publications (e.g. Eddy aet al 1991; Firor, 1990; Houghton et al 1990;
Mayewski et al 1993) *SHOULD BE DISREGARDED*, since they are based on inadequate
data that have, in many cases, been superceeded. Equally obvious is the fact 
that temporal changes displayed by nearly all of the long-term paleaotemp 
records examined here indicate that substantial decadal to multidecadal scale
vaiability is present in regional temperature over the last 1000y. This is, in
all likelihood, a characteristic of most regional climates for the last several
thousand years.

...[Then I got bored typing, sorry]... selective quotes from the rest:

Because of generally sparse data worldwide around the turn of the 1st
millenium, *IT IS IMPOSSIBLE AT PRESENT TO CONCLUDE FROM THE EVIDENCE GATHERED
HERE* that there is anything more significant than the fact that in some areas
of the globe, for some part of the year, relatively warm conditions may have 
prevailed. This does not constitue compelling evidence for a global
"Medieval Warm Period".
...
The generalised behaviour of the global climate of the last millenium as a
Medieval Warm Period followed by a Little ICe Age, each of one or more 
centuries long and global in extent, *is no longer suppported by the
available evidence*.
...

[3] Hughes and Diaz, Climatic Change, March 1994.

- William Connolley