No, this ain’t gonna happen.
Global warming could create peaks of humid heat in the Persian Gulf beyond human tolerance by century’s end, according to a study published on Monday in the journal Nature Climate Change.
If greenhouse gas emissions continue unabated, heatwaves occurring on average once every 10 or 20 years would, by 2100, exceed the capacity of a young, healthy person to maintain a normal body temperature, the study found.
It’s the “continue unabated” which is wrong. Simply because we know damn well that emissions aren’t going to continue unabated. It doesn’t matter whether we use the older SRES scenarios or the newer RCP ones. The mistake, and it is a mistake, whether an honest one or a manipulation, is to take the very worst of the scenarios that have been mapped out and then claim that this is the “business as usual” one.
The point being that no scenario is “the” business as usual one. I know much more about the SRES than I do the RCP ones but the same is true of all of them: all are business as usual ones. That is, all are equally possible outcomes of the normal interplay of the number of people, the wealth of them, and the technology they use to power their civilisation (this is much more explicit in the SRES literature than the RCP).
So, to pull out RCP 8.5, which is what is done here, and claim that this is what would happen is simply wrong. It’s what could happen if the specific emissions pattern modeled happens.
And the lovely thing we know about RCP 8.5 is that we know, absolutely, that it’s not going to happen. It assumes high population growth (higher than is happening), lower technology growth (lower than is happening…..and yes, lower technology growth leads to higher emissions) and poorer people. And that we get more of our primary energy from coal in the future than we do now for fuck’s sake. It’s very akin to A1FI from the SRES. An outcome that just isn’t going to happen.
For example, we know very well that solar is going to become properly price competitive in the next few years. Might be 2020, 2025, but we know it’s coming. It’s already properly competitive in poor parts of the world (because it doesn’t require the building out of the grid). Yet RCP 8.5 assumes that everyone will recapitulate the use of coal as they develop. It just ain’t gonna happen.
But everyone is still using it as their “business as usual” model. They’re just wrong.
And this is more than just a whinge at people publishing alarmist papers before COP in Paris. Google shut down their research arm into alternative energy because they didn’t understand this point. They looked at the business as usual projection then measured what they thought they could achieve against this. They concluded that they couldn’t solve it so they went off to do something else. But their BAU was A1FI from the SRES. They completely neglected to think about how their research might affect other equally likely scenarios.
This emphasis on only measuring the effects of the very worst possible outcome actually closed down a vast research effort into what to do about it.
I’ve actually had a brief interation with Michael Mann over this. Over on Twatter back a while there was a challenge from Mann. So, Worstall, can you do better than this paper showing the effects of climate change?
Yep, I could and I did. The paper had assumed A1FI. I just pointed out that you have to consider all of the BAUs, then assign probabilities to them (not something anyone does) in order to reach your expected outcome. Entirely agreed, for the purposes of that argument, that *if* you assume A1FI then that paper’s fine. But a better answer would be to give us the expected outcome by considering all equally likely scenarios.
He shut up after that. Because that did make the paper better.
This is also how James Hansen gets to $1,000 a tonne as being the correct carbon tax. He looks at the worst possible scenario, calculates (reasonably fairly) the highest possible value of the carbon tax that implies and then states that that’s what the tax should be. No, it shouldn’t be: the tax should be based upon the expected value, calculated by looking at all BAUs and then weighting them by probability.
What annoys me so much about the whole climate change thing is that the scientists are rather ignoring the economics of what’s going in and then ignoring the economics of what’s coming out. I have no hope whatsoever of understanding what they’re saying about radiative forcing and all that. But I do grok most of the economics. And they’re all woefully misusing it.