Michael Mann repudiates the climate emergency

Unlike most climate scientists he understands geology, and has a long-term view of the world, which means there is a lot of weeds for the amateur to get lost in. My advice is read the book, and then go and search out some contrary views.

The future might be all speculation, but once you get further back than yesterday’s dinner, the past can be just as speculative.

Maybe CO2 is a genuine thermostat, but then how do you explain this graph where the earth can be quite cold with high concentrations of CO2 and warm with low concentrations?

Mann deals with some of this by the concept of Earth System Sensitivity, which is the idea that there is a certain amount of inertia in the earth system and it may take quite a time for changes to manifest.

He posits that sensitivity may be higher in interglacials, and lower during glacials, partly a result of the fact that ice sheets, which dominate glacials, reflect a lot of sunlight and therefore act to keep temperature low, despite changes in CO2 pushing temperature in the other direction, and therefore melt very slowly causing temperature to also warm very slowly.

That brake on temperature change doesn’t exist when most of the ice sheets have melted, as they have today, so warming can be more instantaneous.

Perhaps.

I think it needs a lot more research but do please delve into the book – it has a wealth of detail which is hard to convey accurately, or at all, in a short review.

And definitely read the last chapter where I will let Mann speak for himself:

But breathless claims of imminent climate-driven ‘human extinction’ and ‘runaway warming’ are both scientifically unsupportable and unhelpful.

I’ve always been a “new denialist”, or if not always, since somewhere in the 90s. Manmade climate change is a fact, to the extent that emissions of CO2 created by us have some effect on the climate. But to what extent is an open question, as is what to do about it.