Guess which one gets used as business a usual?

Yes, yes, we all know that views on climate change differ. Climate always has changed and always will, perhaps adaptation would be better than mitigation, and then all the way through to the Greenpeace line, we’ll be cannibals cooking each other in the water of the last ice floe using the oil of the last whale to heat it.

It’s still possible for climate change to be real, happening, something we’re causing and even something we should do something about – and also for certain of the climate scientists to be lying through their teeth. The sadness being that many of them are.

This is ever so slightly technical so bear with me.

A wintertime megaflood in California could turn out to be the worst natural disaster in U.S. history by far, and we are making it much more likely, according to an alarming study published this week in Nature Climate Change.

The odds are good that such a flood will happen in the next 40 years, the study says. By the end of the century, it’s a near certainty. (And then another one hits, and another — three such storms are possible by 2100). By juicing the atmosphere, extreme West Coast rainstorms will happen at five times their historical rate, if humanity continues on roughly a business-as-usual path, the new research predicts.

This all turns around that phrase “business as usual.”

The paper is here and this is what they’re modelling:

….under RCP 8.5 forcing.

Now this is wrong and wrong for two reasons. It’s also entirely common and occurs in near all climate change papers we see these days. Yes, sadly, we are being lied to.

The first reason this is wrong:

Guess which one gets used as business a usual?

We have four different sets of ideas about what emissions are going to be in the future. That’s what gives us the radiative forcings being used. No, sorry, we’re not going to start shouting that this is all dangly bits and hairy ones to boot. That’s not the point here.

Instead this is something much less controversial. It’s a standard insistence that all of these are possible. They’re all, in fact, business as usual. It just depends upon what happens to things like population, technological advancement, globalisation and so on. As you will note there’s quite a spread there of radiative forcings – and all should be described as business as usual. Further, when we work out what might happen as a result of climate change we should in fact be looking at what will happen under each of the four sets of assumptions. Because that’s actually how you do it – we’ve some unknowns. Therefore we prepare the results of our modelling according to those varied unknowns.

When you don’t do this you get Jim Hanson’s famous result, that the carbon tax should be $1,000 a tonne CO2-e. That’s not actually what he found. He found that the correct carbon tax could be up to $1,000 per tonne CO2-e. But that was the extreme value if everything, but just everything, went wrong. What we want to know for policy purposes is what is the accurate weighted value of the carbon tax? There’s – to invent numbers – a 1% chance that it should be minus $100, a 1% chance that it should be plus $1,000 and a 98% chance it should be $80. OK, sure, we can adjust for those two 1% possibilities. We could even accept Marty Weizman’s point about fat tails in the probability distribution and so on. But the carbon tax shouldn’t be at $1,000, it should be around and about $80.

This is exactly what our intrepid researchers are not doing here. They are not adjusting for the probability among the varied business as usual pathways. They are only giving us the outcome of the one, the most extreme, pathway.

Sorry, that’s lying.

It’s actually worse than this which gives us our second reason. We do actually know that RCP 8.5 has zero chance of coming to pass. For we’ve already done the things which mean it won’t happen. That is, we’ve changed those other motors of society, globalisation, fertility, population size, technology and so on. 8.5 just won’t happen.

One point is that in about 50 years time we will be using more coal than we do now. In fact, we’ll get a larger portion of our energy from coal than we did 15 years ago. Before all the coal mines started going bust. Before fracking meant we don’t, in North America at least, use coal much to make electricity – we’re certainly not building new plants to do so. Before we made solar cheap (er).

RCP 8.5:

Underlying assumptions about main scenario drivers of the RCP8.5, such as demographic and economic trends or assumptions about technological change are based upon the revised and extended storyline of the IPCC A2 scenario published in Riahi et al.

The A2 scenario:

The A2 marker scenario (A2-ASF) was developed using ASF (see Appendix IV), an integrated set of modeling tools that was also used to generate the first and the second sets of IPCC emission scenarios (SA90 and IS92). Overall, the A2-ASF quantification is based on the following assumptions (Sankovski et al., 2000):

Relatively slow demographic transition and relatively slow convergence in regional fertility patterns.
Relatively slow convergence in inter-regional GDP per capita differences.
Relatively slow end-use and supply-side energy efficiency improvements (compared to other storylines).
Delayed development of renewable energy.
No barriers to the use of nuclear energy.

We’re not in that world, we’re just not. In fact, on near all of them, we’re doing better than the most optimistic of the earlier set of emissions pathways, the SRES.

There are two lies common in current climate change research. The first is to assume that RCP 8.5 is the only business as usual forcing scenario. It isn’t. To present only the one result, from this emissions profile, is to be presenting only the worst outcome, not the range which it is agreed are likely.

Secondly, we’re simply not on RCP 8.5. We’ve already done things to the world economy which mean that we’re not. In fact, of the emissions pathways RCP 8.5 is pretty much the only one we know absolutely isn’t going to happen. Thus results scaring the knickers off us if it does aren’t really being truthful, are they?

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At last someone with claims to be a citizen economist is starting to think like an economist. Now all he has to do is to read his fave foundational doccie for carbon tax, the Stern Report, with his economist specs on and the ghost of Carbon Tax Future will be laid to rest.


Dittos. Tim, you are right; “Sorry, that’s lying.” But your continual brainwork to devise the “correct” value of a carbon tax, given educated analysis of their myth, is enabling their lying. And it ignores the fact that the tax will be collected, spent, increased, and made un-repealable by people who don’t care at all what the “correct” tax would be, provided they always have the claim that the (unmeasurable) alternative is anthropomorphic catastrophe. It is someone else’s earnings to spend on a whim, that’s all that matters to them.

bloke in spain
bloke in spain

It’s a good rule of thumb, in life, you learn more about people from the lies they tell you than you ever will from the truth. So the lies, the climate calamatists are retailing, tell us climate calamity ain’t a possibility. Or they wouldn’t need to lie about it. So the right level for a carbon tax is zero.


Can’t wait for the next ice age.


Pendantic point – a carbon tax of $80/tonne equates to a carbon dioxide tax of about $290/tonne, which is a number I’ve never seen in this context.
I think you meant a carbon dioxide tax of around $80/tonne, which means a carbon tax of about 12/44ths of that.

Rhoda Klapp
Rhoda Klapp

“So the right level for a carbon tax is zero.”

Cos it’s a scam, a holdall hobgoblin to excuse the implementation of a de-industrialisation agenda which ought to be roundly rejected every time it is mentioned.


IMHO, the right time to start pontificating about the “correct” level of “Carbon Tax” is when the modellers finally get their act together and produce some software that actually has some genuine skill in prediction and manages to make an actual causative link between CO2 and global warming – rather than the present “it looks like it might be doing it, so let’s assume it is and weight it accordingly”. We still seem to be at the stage of the criticism of the American military during Vietnam of “making important that which we can measure rather than measuring that which… Read more »


The whole climate change debate is unfortunately tinged with distrust of hidden agendas. The left largely believes in a very strong central government, and to all appearances it also appears that they think that people in the west should on average be poorer. Hence all the emphasis on high density housing, very small cars, high taxes, and the occasional longing for a plague that wipes out much of humanity (though presumably not in their neighborhoods). To the extent that people perceive the advocates of an intense crackdown on the use of carbon as also being used to support their agenda… Read more »