More thoughts on global temperature

Having taken the trouble to plot all eight nine popular global temperature series together on one graph at monthly resolution — something the other seven billion of you don’t seem to have bothered with — it may be fair to spare us the indulgence of a few simple observations:

1. They’re all the same

Millions of bullshitter-hours of trouble making and thousands of scientist-hours of patient rebuttal — this urbanisation correction, that homogenisation, this clever interpolation, that gap filling; ignore those drifty satellites … not even surface temperatures; no, use the pattern but not the number — all to naught. For the purpose of grasping what we face it doesn’t matter. They’re all the same:

Global monthly temperatures since 1850 -- instrumental, satellite and reanalysis

Global monthly temperatures since 1850
— instrumental, satellite and reanalysis estimates

2. Monthly matters

OK, it’s my bias, but monthly plotting matters. This is a variable system. Folks know that, implicitly (it’s called weather). Hiding that variation by annual or long moving average plotting destroys information and, in my view, degrades veracity. (Much of the month-to-month variation in the last 100-odd years appears to be real variability, given the close agreement of satellite and instrumental series and the similar high frequency noise levels throughout. The apparently increasing variability before about 1920 is likely to be an artifact due to reducing spatial coverage of historical measurements.)

3. It’s the trend, stupid

Global warming is a slow motion train wreck. What happens this year or even this decade isn’t really interesting. What terrifies is the long trend, particularly its acceleration. So, purists, why hide that? Put it front and centre where all can see. And, by the by, you might note that all that “impossible to believe” IPCC modelling just happens to fit simplistic extrapolations of common accelerating functions pretty much spot on, depending on your choice of greenhouse gas concentration pathway (“RCP“):

Global monthly temperatures long extrapolation

Global monthly temperatures — long extrapolation