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The Financial Times tells us that – possibly you understand – as many as 3 billion people could find themselves in unliveable conditions as a result of climate change.

Climate change could bring near-unliveable conditions for 3bn people, say scientists

There’s an awful lot resting on that ‘could’. Far too much in fact. For this statement assumes that the socioeconomic system takes a turn very much for the worse, then combines that with an emissions pathway that we already know isn’t going to happen. That is, the scientists aren’t in fact saying that this could happen. The correct statement is that ‘unliveable’ is worse than it could possibly be.

But then that’s not likely to be the sort of thing that a newspaper will publish on the day COP 26 opens.

Up to 3bn out of the projected world population of about 9bn could be exposed to temperatures on a par with the hottest parts of the Sahara by 2070, according to research by scientists from China, US and Europe. However, rapid reductions in greenhouse gas emissions could halve the number of people exposed to such hot conditions.

That’s not actually true. Assume, for a moment, that the predictions of the interaction of emissions and temperatures are correct – that their concerns over the effects of rising median temperatures, maps out. The statement is still not true. For they are assuming both something that is most unlikely to happen and also something that we already know is not going to.

The source paper is ‘Future of the human climate niche’, within which we see their modelling assumption about the future:

The historical inertia of the human distribution with respect to temperature…contrasts sharply to the shift projected to be experienced by human populations in the next half century, assuming business-as-usual scenarios for climate (Representative Concentration Pathway 8.5 [RCP8.5]) and population growth (socioeconomic pathway 3 [SSP3]) in the absence of significant migration

That ‘inertia’ of their distribution with respect to temperature tells us that humans can and do live, happily enough, in many temperature regimes. But despite this, the authors’ assumption is that this time it will be different; that it will all be dangerous in some manner.

More important are those two assumptions they’re making about that future. RCP 8.5 we addressed in a recent paper; it’s not going to happen. The original model was included in the portfolio simply to give an edge case – one that was beyond the edge of likely, reasonable outcomes –so as to give an outer edge to descriptions as to how bad it might get. It was never a reasonable prognosis of any likely future.

Further, it required that as a society we exhaust conventional oil and gas deposits, for some reason decide not to exploit unconventional ones (via, say, fracking), do not develop renewables, and thus turn back to coal in order to power industrial society. But we haven’t exhausted conventional deposits, have gone fracking – even if not enough – have not turned back to coal and have developed renewables.

RCP 8.5 simply isn’t a possible outcome today. It also absolutely isn’t ‘business as usual’. We’d have to reverse near all developments in energy of the past 30 years to make it so. In fact, we’d have to go back to partying with coal like it’s 1899 and worse, something we’re simply not going to do.

This is made worse by the use of SSP3 as the socioeconomic structure. This is a model in which globalisation reverses – not just stands still: reverses – and countries turn back to regional or even national self-sufficiency, even to the extent that technological dispersion –renewables technology, say – slows. This also isn’t something that’s likely to happen and it’s most certainly not ‘business as usual’, nor a simple projection of today’s global forces. It would, at minimum, require substantial changes in policies, not continuations of current ones.

Combining those two models – RCP 8.5 and SSP3 – is one of those things that shouldn’t be done. They are, in fact, mutually exclusionary. Population is not exogenous; it’s closely linked to economic wealth and development. Therefore, taking a high economic growth model (RCP 8.5) and combining it with the higher population of a low economic growth model (SSP3) is really not on. That produces far too many rich people all emitting from coal, when the actual models insist that if we’re all rich there will be fewer of us, if more of us then that will be because we’re poorer.

But then there’s that battle to gain eyeballs during COP26. Heaven forfend that people stop promoting futures that we already know aren’t going to happen. Nor fail to compound those extremes by mixing and matching outcomes that are mutually exclusionary.