Michael Mann repudiates the climate emergency

Could Michael Mann, the inventor of the so-called Hockey Stick graph, be a covert “New Denialist”? Or is there a split happening in the climate catastrophe camp. That’s two readings of Mann’s latest book Our Fragile Moment.

Either being true would be a good thing, and both even better.

The “new denialists” is a new term coined to describe people who believe that while climate change is real, it is an open question how much is manmade, and what the policy response should be.

Mann is not someone who you would normally associate with such a position.

He has been famous in climate circles since 1998 when, as a newly-minted doctor in geology and geophysics, he was the principal author of Mann, Bradley and Hughes 1998 (MBH98), a paleoclimate reconstruction of 1,000 years of earth’s temperature which showed unprecedented warming in the late 20^th century.

It undermined the consensus view which was that temperature fluctuates quite significantly over centuries, and it was probably cooler now than it had been during the Roman climatic optimum and the Medieval warm period.

You may have seen its star role in Al Gore’s agitprop An Inconvenient Truth (“agitprop” because the film was ruled by a British court to be unsuitable for showing to school students without accompanying corrections because it contained “nine scientific errors”).

Gore had the graph on a large backdrop and emphasised the steepness of the blade, and thus the urgent need to stop CO2 emissions, by rising-up beside it in a scissor lift while holding a large pointer in his hand. Very dramatic

It and successor hockey sticks are the standard bearers (if you’ll forgive me mixing metaphors) of climate change catastrophism, and they’ve been used to hit (metaphor again) “climate deniers” over the head.

I’ve never had any regard for the hockey stick.

Not only did it purport to erase the consensus on the basis of one reconstruction, but its statistical techniques were shown to produce hockey sticks out of any random data. So it seemed unlikely to be correct.

But on top of that Mann did something which is completely impermissible in statistical analysis.