Michael Mann is back. Not that he ever went away. But in a new paper he and three co-authors say CO2 and aerosols explain everything. There is no climate variability. Prompting Judith Curry to ask “How does this stuff get published in a journal like Science?” And answer her own question: “Peer review is sooooo broken.”
It is a remarkable story, and Curry does not mince words. “Mann’s quest to cancel the Medieval Warm Period and now the AMO, in the interests of showing that recent warming is 100% anthropogenic, is not at all convincing to scientists who understand anything about climate dynamics and global climate models.” The AMO?
Yes indeed. The Atlantic Meridional Oscillation. Oh that thing, you say. But in case you did not, it’s a very complex surface temperature cycle in (at least this part was obvious) the Atlantic Ocean, that very famous and very big body of water. One of many such connected bodies that famously contain way more CO2, and heat, than the atmosphere. Fifty times as much and a thousand times as much respectively, according to Patrick Moore in Fake Invisible Catastrophes and Threats of Doom (p. 67) which is why minor changes in the ocean’s absorption or degassing have a major impact on the atmosphere, to answer a question we posed last week. And even most alarmists take the AMO pretty seriously.
So why do Mann and his co-authors hate it so? What did it ever do to them? Well, they don’t completely hate it. They just say that it is not an intrinsic phenomenon. They say it is explained by GHG forcing plus the cooling caused by sulphate particles from volcanic activity. The oceans are basically just like a bathtub full of water unless some fool or some volcano stirs them up. Which brings us to Mann’s real objection to the AMO.
Whatever climate change is natural cannot be man-made. And Mann believes it is essentially all man-made. Or person-made if you prefer. So having gotten rid of the Medieval Warm Period with a hockey stick carved from tree rings, because it looked natural and suggested natural fluctuations, he’s after other natural fluctuations as well because what they do to him is refute his entire vision of climate.
He won’t get them, of course. The MWP withstood his onslaught and the Little Ice Age still sits there scowling. And the Roman Warm Period, the Holocene Climatic Optimum, the Last Glacial Period, the entire Pleistocene, the Eocene, the PETM, and other stuff going back into the time of the dinosaurs and beyond are like an enormous climate change out there, and all laughing at him. But even if we say OK, Mann flattened everything since the Norman Conquest and nothing happened earlier, Curry objects that there’s still the 20th century. And a major methodological problem.
As to the former, “Wow. In one fell swoop, the pesky problems of the ‘grand hiatus’ in the mid 20th century, debates over the attribution of 20th century warming and the role of multidecadal internal variability, and the difficulty of attributing the recent increase in Atlantic hurricane activity to AGW, all go away. Brilliant! Almost as ‘brilliant’ as the Hockey Stick.”
As to the latter, the methodology not the hockey stick, as you may know, Mann did it in the lab with a computer model. AGW Clue isn’t even a fun game because we always already know the weapon and the room, and the suspects aren’t hard to find either. But also in this case, as we noted two weeks ago, computer models don’t do the 20th century very well, never mind earlier periods, and since they’re meant to predict the future their incapacity to predict even the known recent past is a big problem.
Not to Mann, who thinks the models are better than life. But to many scientists who worry about the models’ mishandling of aerosols among many other things. And to Curry, who says “Relying on global climate models, which don’t adequately simulate the multi-decadal internal variability, to ‘prove’ that such multi-decadal internal variability doesn’t exist, is circular reasoning (at best).” And at worst? Well, here’s where she went “How does this stuff get published in a journal like Science? Peer review is sooooo broken.”