Climate Change & Climate Variability (part 12)
In this article I cook us a dish of HadCRUT thermidor (see what I did there?)
In part 11 of this series I promised fiddling and revelation so let’s get right down to it!
Here is the HadCRUT.5.0.2.0 annual mean global temperature anomaly, fresh out of the oven this morning. You can go and grab the very same data for yourself from here to check that I am not cheating.
I don’t know about other folk but when faced with this particular tray bake I am sore tempted to split the series into four unequal chunks using only my eyeballs and a sharp knife. You can see where I’m going to bring that knife down, and I shall serve up the following slices:
Steam age 1850 – 1909 (n=60)
Combustion age 1910 – 1944 (n=35)
Nuclear age 1945 -1977 (n=33)
Satellite age 1978 – 2023 (n=46)
Not only do these periods align with turning points that are almost certainly going to mark differing climate epochs but they also align with technological developments and sweeping changes in society. In turn these will impact on the science and the purpose of that science. Both WWII and the cold war spurred meteorology to greater heights (sometimes literally), with different data collected for different purposes to those back in the age of steam: our science and the methodologies upon which it depends do not exist in a vacuum.
Estimating The Variance Of A Squirming Series
My ancient eyeballs have seen more graphs than many folk have had hot dinners, and so it is easy for me to ogle this slide and make wild statements about the variance being invariant. By that I mean the variance of the annual estimates doesn’t change that much over time. An analogy is replacing your baggy but trendy torn and faded jeans with Spandex leggings. These are going to hug every lump and bump and bend, and so it is with this data. There’s no bagginess in this slide, no sticky out bits beyond the arms and legs, and no soggy bottom. We are talking the Hadley Centre’s equivalent of Spandex and this tells me the variance of the global mean anomaly hasn’t changed over time as we might expect if climate change is all about temperatures going wild rather than just up.
But let me formalise this with elegance, gusto and a touch of garlic…
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