Who knew what when, again?

WKWW refers. The shiny new Parliamentarians’ Guide to Climate Change says "Climate change is an area fraught with disinformation, creating a vital need for reliable, accessible and trusted data and analysis". How true. Naturally, it will hold itself to the highest standards, and rigourously eschew any misleading statements, such as That a warming planet is chiefly the result of human carbon emissions is extremely well understood. The greenhouse effect has been known about since the 19th Century and the first detection of human-caused warming was in the 1930s... oh, hold on. This "first detection" is Callendar's stuff. He did indeed make some kind of global temperature series, and he did indeed think It Woz Us Wot Dun It, but to present this as agreed upon or sure or even as "detection" is distinctly dubious¹; we have IPCC '90 saying Global - mean surface air temperature has increased by 0 3°C to 0 6°C over the last 100 years... The size of this warming is broadly consistent with predictions of climate models, but it is also of the same magnitude as natural climate variability Thus the observed increase could be largely due to this natural variability, alternatively this variability and other human factors could have offset a still larger human-induced greenhouse warming. IPCC '90 had not "detected" human-caused warming; claiming it for the 1930's is dodgy.

Don't ask me about the rest of it; I stopped at that point.

Notes

1. I'm pretty sure that calling it "the first definitive proof of rising global temperatures" is wrong too. We like it, now, because he turned out to be right (and British, too, which is nearly the same thing). As Spencer Weart puts it, It all sounded dubious to most meteorologists. Temperature data were such a mess of random fluctuations that with enough manipulation you could derive all sorts of spurious trends. Taking a broader look, experts believed that climate was comfortably uniform.