[TheForge] OT weather v. climate

[schade at acegroup.cc]

On Mar 3, 2007, at 11:58 AM, Kathy wrote:

> To Bob,
>
> Far be it from me to ask embarrassing questions, but doesn't the 
> record keeping
> of the British over the last three centuries prove very nicely that 
> your "thirty
> years" comment, when taken in perspective, was closer to weather than 
> climate?

Mike,

I'm not embarrassed. Why would I be?

It would seem to me that the longer the sample of past weather the 
better the ability to predict future climate would be. What does the 
300 years of British records indicate? You didn't say.

> Than of course, we can't forget the inconveniently historic example of 
> the
> centuries long cold snap called the middle ages.
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This is what the site cited earlier has to say about that,

Bob
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The Medieval Warm Period was just as warm as today
(Part of the How to Talk to a Climate Sceptic guide)

Objection:
It was just as warm in the Medieval Warm Period as today, in fact 
Greenland was green and they were growing grapes in England.

This one often comes with additional anecdotal evidence, but it is not 
often useful to get into those details, just refer to the wealth of 
proxy studies that refute this idea.

Answer:
There is actually no good evidence that the MWP was indeed a globally 
warm period comparable to today. Regionally, there may have been places 
that did exhibit notable warmth but all of the various global proxy 
reconstructions agree that it is warmer now and the temperature is 
rising faster than at any time in the last one or even two thousand 
years. Anecdotal evidence like that above can never tell you a global 
story.

NOAA presents a whole selection of proxy studies together with the data 
they are based on and these can be found here: 
http://www.ncdc.noaa.gov/paleo/paleo.html

Specifically, they have this to say about the MWP:

"The idea of a global or hemispheric "Medieval Warm Period" that was 
warmer than today however, has turned out to be incorrect."

http://www.ncdc.noaa.gov/paleo/globalwarming/medieval.html

In specific answer to the "grapes used to grow in England" bit, I like 
to point people here:

http://www.english-wine.com/index.html
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