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.

Grant Shapps on the campaign trail. Photo: Getty
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Grant Shapps resigns over Tory youth wing bullying scandal

The minister, formerly party chairman, has resigned over allegations of bullying and blackmail made against a Tory activist. 

Grant Shapps, who was a key figure in the Tory general election campaign, has resigned following allegations about a bullying scandal among Conservative activists.

Shapps was formerly party chairman, but was demoted to international development minister after May. His formal statement is expected shortly.

The resignation follows lurid claims about bullying and blackmail among Tory activists. One, Mark Clarke, has been accused of putting pressure on a fellow activist who complained about his behaviour to withdraw the allegation. The complainant, Elliot Johnson, later killed himself.

The junior Treasury minister Robert Halfon also revealed that he had an affair with a young activist after being warned that Clarke planned to blackmail him over the relationship. Former Tory chair Sayeedi Warsi says that she was targeted by Clarke on Twitter, where he tried to portray her as an anti-semite. 

Shapps appointed Mark Clarke to run RoadTrip 2015, where young Tory activists toured key marginals on a bus before the general election. 

Today, the Guardian published an emotional interview with the parents of 21-year-old Elliot Johnson, the activist who killed himself, in which they called for Shapps to consider his position. Ray Johnson also spoke to BBC's Newsnight:


The Johnson family claimed that Shapps and co-chair Andrew Feldman had failed to act on complaints made against Clarke. Feldman says he did not hear of the bullying claims until August. 

Asked about the case at a conference in Malta, David Cameron pointedly refused to offer Shapps his full backing, saying a statement would be released. “I think it is important that on the tragic case that took place that the coroner’s inquiry is allowed to proceed properly," he added. “I feel deeply for his parents, It is an appalling loss to suffer and that is why it is so important there is a proper coroner’s inquiry. In terms of what the Conservative party should do, there should be and there is a proper inquiry that asks all the questions as people come forward. That will take place. It is a tragic loss of a talented young life and it is not something any parent should go through and I feel for them deeply.” 

Mark Clarke denies any wrongdoing.

Helen Lewis is deputy editor of the New Statesman. She has presented BBC Radio 4’s Week in Westminster and is a regular panellist on BBC1’s Sunday Politics.