On 31/07/2019 19:45, JGD wrote:
On 31/07/2019 16:15, Spike wrote:


The problem you have with the 100-200 years time-scales is that if you
applied it to the LIA, one would swing between squandering a nation's
resources battling warming, or battling cooling, depending on where in
the LIA you chose as a datum.


Global temperature effects during the so-called Little Ice Age are
estimated to have been relatively small, maybe 0.5C as a maximum and
more likely significantly less than that. (Granted, in some regions like
Western Europe there were greater effects, but we're talking about
GLOBAL cooling/warming here.)

In contrast, the present warming period shows a global rise of 1C in the
past 100-150 years (with something like 0.7C in the past 40 years) and
the rise is continuing inexorably at 0.1-0.2C/decade - probably 1.5C by
2050.

So any appeal to the LIA doesn't carry much weight I'm afraid.


However the claim that the top ten warmest years have been in the last
20 years is completely misleading.

Temps over about the last 50 years have done this (ascii graph)..


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With fairly big rises in the '70s followed by a long flat spot since
about 2000.

So when would the hottest years occur? That right in the last 20 years.
So it doesn't really mean a thing other than global warming has slowed
almost to a stop despite CO2 continuing to rise at an increasing rate.

So the next question is why didn't the models produced in the '80s
predict this?

then can the current models predict what is going to happen over the
next ten years?

If they don't are the climate modellers going to actually admit they
don't really know why the climate is changing?