Global warming and externalities

How a carbon tax can "solve" global warming

Tim Worstall (yes, when he's not trolling he's quite good) has a piece up at the Telegraph explaining how carbon taxes work, and why they could "solve" global warming:

In economic theory, the problem here is that my actions that create emissions also damage someone else. But I don't have to pay for the damage I've caused. This is called an externality and the economists' solution is something called a Pigou Tax. That is, we add a tax equal to the damage I'm doing, so that I do pay for that damage.

Worstall cites the Stern Review's figure of $80 per tonne of CO2 as a good starting ground for where to set a carbon tax, and explains why it's the most efficient way to deal with climate change:

As a made-up example: my car emits one tonne CO2 when I drive it to buy fresh bread for lunch. That's $80 of damage I cause in the future by doing so. But the benefit to me is trivial: if you paid me 50p (alright, £5 in the rain) I'd cycle instead and not emit the CO2. The value to me of driving is that 50p; the costs to someone else are the $80. Clearly, this is a bad deal for everyone else: they're bearing costs much greater than the benefit to anyone at all. An $80 a tonne tax would get me cycling and that would be a good thing: I've stopped doing something where the benefit is lower than the cost.

However, we've a pregnant woman in pre-eclampsia. She needs to go to hospital in an ambulance which is going to emit that tonne, that $80 worth of CO2. Without it she and the child will be dead; with it they'll be fine. We usually value a statistical life in the £2 – 3 million range. That's what the railways will spend on safety to save a life on average. Or we could use the £50,000 that NICE applies to one year of good-quality life. If your drug treatment costs more than this, then you won't get it on the NHS; less and you might. Different numbers but much the same outcome: burn that fuel and damn the $80 of future damages, because they're much lower than the benefits that are achieved right now from burning that fuel.

This efficiency is why a carbon tax – or the harder to impose, but fairer and economically identical "cap-and-trade" system – really is the best way to deal with global warming. By definition, it deals with "bad" emissions while allowing "good" ones, and it does so far better than a legislature could ever hope to with a sprawling network of tariffs and subsidies.

But Worstall does somewhat overstate the case in one area, when he writes:

The other part [of a reader's question] – what's the point if we're not going to spend the money on green projects? – misunderstands the purpose of the tax. We're not trying to raise money: we're trying to change prices.

Changing prices is only half the effect of a carbon tax – or any Pigou tax. The other half is compensating the "victim" for their loss.

Suppose we live in a little two person economy where every tonne of CO2 you produce causes $80 worth of flooding damage to me. Imposing a carbon tax solves half the problem, in that it stops you polluting if you only get $10 benefit from it. But it doesn't solve what happens if you can make $100 from polluting.

In that case, you pay $80, and make $20 profit. I'm still left with $80 of flooding damage. The proper use of the money raised is to compensate the me for that loss. Otherwise, a tax which merely sorts out externalities becomes a revenue-raising tool of Government. In practice, this means that money raised from a carbon tax should be used on "green projects".

Which would annoy Worstall's fellow Telegraph blogger James Delingpole.

Anti-carbon tax protestors in Australia. Photograph: Getty Images

Alex Hern is a technology reporter for the Guardian. He was formerly staff writer at the New Statesman. You should follow Alex on Twitter.

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The trouble with a second Brexit referendum

A new vote risks coming too soon for Remainers. But there is an alternative. 

In any given week, a senior political figure will call for a second Brexit referendum (the most recent being David Miliband). It's not hard to see why. EU withdrawal risks proving an act of political and economic self-harm and Leave's victory was narrow (52-48). Had Remain won by a similar margin, the Brexiteers would have immediately demanded a re-run. 

But the obstacles to another vote are significant. Though only 52 per cent backed Brexit, a far larger number (c. 65 per cent) believe the result should be respected. No major party currently supports a second referendum and time is short.

Even if Remainers succeed in securing a vote, it risks being lost. As Theresa May learned to her cost, electorates have a habit of punishing those who force them to polls. "It would simply be too risky," a senior Labour MP told me, citing one definition of insanity: doing the same thing and expecting a different result. Were a second referendum lost, any hope of blocking Brexit, or even softening it, would be ended. 

The vote, as some Remainers note, would also come at the wrong moment. By 2018/19, the UK will, at best, have finalised its divorce terms. A new trade agreement with the EU will take far longer to conclude. Thus, the Brexiteers would be free to paint a false picture of the UK's future relationship. "It would be another half-baked, ill-informed campaign," a Labour MP told me. 

For this reason, as I write in my column this week, an increasing number of Remainers are attracted to an alternative strategy. After a lengthy transition, they argue, voters should be offered a choice between a new EU trade deal and re-entry under Article 49 of the Lisbon Treaty. By the mid-2020s, Remainers calculate, the risks of Brexit will be clearer and the original referendum will be a distant memory. The proviso, they add, is that the EU would have to allow the UK re-entry on its existing membership terms (rather than ending its opt-outs from the euro and the border-free Schengen Area). 

Rather than publicly proposing this plan, MPs are wisely keeping their counsel. As they know, those who hope to overturn the Brexit result must first be seen to respect it. 

George Eaton is political editor of the New Statesman.