Guest essay by Neil Catto
The other day I conducted a presentation using the UK CET, like I have on several occasions. Along with explaining it as the longest recognised instrumental record of historical temperature anywhere on Earth, it is the best record we have to understand long the past.
Fig 1 Central England Mean Monthly Temperatures 1659-2012
As part of this presentation I point out that the temperature from 1659 to 2012 has only increased 0.87 Deg C in 353 years, or equivalent to 0.025 Deg C/decade. Considering this is a recovery period from the Little Ice Age it is hardly surprising and just part of natural variation. At this stage I normally get a few “really?” questions.
“The UK MetOffice’s own figures”, I reply.
The other day however was a bit different, someone in the audience asked “so how long will it take to get to the dangerous 2 Degrees C?”
Pause, why hadn’t I worked that one out before? Quick calculation done, 800 years I replied.
“Say again?”
I recalculate, and say “800 years given the current trend”. Gobsmacked audience!
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Thanks for that.
Ulric
The main point of my argument is that Neil Catto (the author of the blog post) is wrong to use the 353 year trend to predict further warming. That’s it really. I made no comment about what caused the warming other than to suggest the CET record provided more support for a CO2 influence than it did for a natural recovery from the LIA.
It was others who changed the point of discussion.
Thanks again for your input.
John Finn says:
“I made no comment about what caused the warming other than to suggest the CET record provided more support for a CO2 influence than it did for a natural recovery from the LIA.”
If warming from CO2 had been cancelled out by negative NAO conditions and hence CET temperatures from 1950 to 1987, and then had augmented the positive NAO conditions and CET temperatures from 1988 onwards, then we should get some idea of the relative level of forcing by how negative the NAO (and the AO) has returned to since 2009. 😉