There have been suggestions that Jo Nova might be trying to hide or ignore the most recent boreholes graph from Huang et al. So here it is. This is the last 2,000 years according to 6000 boreholes, with the last 100 years also using the “instrumental record” which gives us that hockey-stick uptick at the end. Below I explain the pros and cons of this study and update my thoughts.
A borehole sounds like a bit-of-a-stretch as a proxy. How could we tell if the world was warmer in 1066 by drilling a hole in the ground? Yes, fair point. But what makes boreholes useful is that they are global and there is a lot of data: specifically 6,000 holes all over the world.
I’ve been looking at boreholes in more detail, analyzing them in the light of newer proxies. When all the evidence is considered, boreholes turn out be not-much-use at giving us meaningful numbers in degrees C, and in my opinion, not-too-hot at telling us the “when” of an event either. Too much depends on assumptions.
But what are they good for is that, when combined with […]
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