I really thought that maybe Watts Up With That (WUWT) was keeping quiet about Topher Field’s 50-to-1 video project because they’d realised just how silly the actual calculation was. Oh, how wrong I was. There is now a new post claiming that the ratio really should be 100-to-1.
For those who don’t know, Toper Field’s 50-to-1 project was based on a calculation claiming that the cost of mitigating against climate change was 50 times more expensive than doing nothing and simply adapting to climate change if and when it happens. It is a very silly calculation (initially done by one Christopher Monckton) which I’ve discussed before. It’s also been debunked by Michael Tobis. The new post on WUWT seems to be claiming that because the Equilibrium Climate Sensitivity (ECS) is likely to be lower than previously thought, one can show that the actual ratio is more likely to be 100-to-1.
I’m not going to say much more because debunking this is actually quite trivial. It is based on an assumption that a carbon tax of 1% of world GDP would reduce CO2 emissions by 5%. Simplistically, therefore, the most this could ever be is 20% of world GDP (and even that is wrong because as CO2 emissions reduce, the tax revenue will drop). The other assumption is that adapting to climate change will cost about 1.5% of world GDP (probably wrong, but that’s the assumption used). Therefore, in a simple sense, the most the ratio could ever be is about 13-to-1. So, changes to ECS do not really influence this calculation at all given that it is based only on the reduction in CO2 emissions, not on the reduction in temperature. Michael Tobis actually argues that a calculation using consistent information actually results in it being 12.5-to-1 in favour of mitigation.
I, however, don’t really know if any of these types of calculation can be done with any real rigour. The uncertainties must be very large. I do know, however, that Topher Field’s calculation and the new WUWT one are both nonsense.
Wotts Up With That Blog 
This sort of statistic is impossible to prove and impossible to disprove. I guess they just want the figure to be out there in black and white, so that they can endlessly repeat it down the denial echo chamber as if it’s an unassailable fact.
In general I agree. In this particular case you can, however, quite easily show that their calculation is wrong. They go from an estimate that a carbon tax with revenues of $700 billion would reduce CO2 emissions by 5% to then claim that preventing 0.17 degrees of warming in the next decade would cost $420 trillion. Not only is the calculation nonsensical, in that preventing much warming in the next decade is not possible but, based on their own assumptions, once the revenues reach $14 trillion, CO2 emissions are zero and hence additional revenues can have no more effect. Furthermore, of course, if the carbon tax ever got that high, presumably the carbon emissions would be low and the revenues would actually be quite small (again based on their assumptions). So, I agree that proving these kind of things is probably impossible, but disproving this particular calculation is actually quite easy.
Wotts, the revenue may be quite low, but if the tax needs to be maintained at that level for zero net emissions, then presumably the additional cost of non-emitting energy sources relative to energy sources is still close to that level. Ergo the cost of the policy will be a sizable fraction of the 14 trillion; or at least it would be if you use their highly dubious assumptions that:
a) The cost of renewable energy will not fall with additional investment, thereby reducing the required tax level to gain zero emissions; and
b) The price of fossil fuels will not rise with increasing demand in the absence of any price on carbon.
(b) is particularly odd in that one of the more sophisticated denier arguments is that a carbon price will be ineffective as policy because, by reducing demand for fossil fuels, it will lower the market rate for fossil fuels thereby becoming ineffective. It would not surprise me to find deniers accepting both Monckton’s calculation and (inconsistently), that argument as well.
On the other hand, the assumption that the cost of decarbonizing the economy will be linear with percentage reduction is also very dubious. The cheapest, easiest economic activities will decarbonize first, meaning it will require a higher carbon tax rate per percentage reduction in emissions for each successive percentage point reduction. It is my hope (and a reasonable hope) that the fall in cost due to technological gain and some economies of scale will be more rapid than the rise in price that would occur if technology remained stagnant. That, however, is certainly not guaranteed. This last point is not a criticism of your rebuttal in that (I believe) Monckton assume linearity as well, so it is perfectly acceptable to accept his assumption in showing the fallacy in his calculation.
Finally, to be consistent we must include as part of the cost of action the cost of adaption to the committed warming. The choice is between policies of mitigation plus adaption to committed warming, or adaption to the full warming without mitigation (or some alternative policy within that range). This does not help Monckton’s argument very much in that he places such a ridiculously low value on the cost of adaption. It does, however, slightly increase your upper limit.
Tom, I suspect you’re probably right. I would agree that it is all going to be much more complicated than any simple calculation would indicate. As you mention there are various factors such as probably reductions in the cost of renewables, the likely increased cost of fossil fuels and that the effect of a tax will likely not be linear.
I should probably also have made clearer that I was simply referring to the revenue associated with a carbon tax. You’re right that even if the revenue was to be low (because emissions were low) there would be costs associated with changing to a low-carbon economy that would probably be comparable to or maybe slightly higher than the maximum possible revenues associated with a carbon tax. Despite this, we’re still nowhere near the 50-to-1 or 100-to-1 claimed by Topher Field and WUWT.
Actually Tom, maybe you can enlighten me about something. A basic back of the envelope calculation would suggest that at least 10% of the world economy is associated with providing energy (based on how much I think I pay for various different forms of energy). Given that, we’re spending about $7 trillion per year on energy. Hence, if we think $14 trillion per year could allow us to transform to a low carbon economy, we’re at roughly a factor of 2. Given various uncertainties, maybe one could argue that it ultimately sounds like it would end up being about the same. Of course, this is my basic – probably wrong – calculation. Maybe you have more insight with regards to this.
Any attempt at mitigation is futile while China and India are going full steam ahead with coal fired power. All of our reductions will be more than offset by their increases. It’s a lot of financial pain for no climate gain. Take a serious look at the emissions growth for these two countries and you’ll see that it’s not possible for us to stabilise global CO2 levels, regardless of the cuts we make. 50 to 1 may be a fair long term estimate as we’re going to be constantly urged to throw more and more money into this money-pit.
Doing nothing costs nothing, which means plenty of money available for adaptation, and then we’ll only need to spend money on the actual necessary adaptations.
You’re assuming, of course, that spending anything on mitigation is absolutely wasted rather than potentially developing new technologies, creating jobs and advancing our economies.
Do nothing costs the earth.
Indeed, that’s the concern. There was a quote in hotWhopper comment, attributed to George Carlin, that went “The planet’s fine. It’s the people who are f**ked”.
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