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Spike · January 17th 20, 10:11 AM posted to uk.sci.weather

On 15/01/2020 12:22, wrote:
On Wednesday, January 15, 2020 at 10:37:47 AM UTC, Spike wrote:

The Roman Warm Period? The Medieval Warm Period? But in those times
atmospheric CO2 was lower than at present, meaning crops, etc, would be
poorer. But humankind survived that heating of the planet.

I expect the data-collectors of the group could easily say how far south
from, say, the environs of Stoke-on-Trent one would have to travel to
experience a 1.5degC increase in the climate - I'm guessing somewhere
as far as Salisbury or Chichester.

We have already surpassed the warmth of the MWP.

Modern proxies show lower temperatures than MWP proxies. Now, if proxies
act as a 'smoother' of 'filter' of the data, that implies that
temperatures in the MWP peaked at higher values than the proxies show,
just as is shown by the current divergence problem. So by saying that
instrument readings show that it is warmer now than then is not to
compare like with like.

No-one is growing grapes in Yorkshire...

I have a vague recollection of HH Lamb (Climate History and the Modern World, and the previous 'Climate' book) referring to it being 0.7C warmer than the coldest part of the C20. The difference is that we have warmed so quickly this time. Some people kept reading those sources for too long into the current warming period. It is nice to keep textbooks but we have to be careful as the details can become out of date.

Spike, you attach a great significance to the MWP and the LIA - neither were truly global phenomena in the sense of the current global warming crisis.

Both the LIA and the RWP and MWP were 'written out' of the Hockey Stick
graph on which so much was based, yet apparently there's scientific
papers numbered in the thousands describing them. These periods have
been described as 'occurring all over the planet' yet are not classed in
some quarters as 'global', for some reason.

PS if you were confident in your assertions, would you not identify yourself?

Sorry, too many internet stalkers following me around, including one or
two that have turned up on this group.

Julian Mayes

--
Spike