How do you price the death of the world?

Climate change is hard to account for.

Grist's David Roberts writes about the distinction between climate change and other environmental problems:

The first difference is that carbon dioxide is not like other pollutants… The typical climate-policy targets that get thrown around — reducing emission rates by 80 percent by 2050, for example — are relatively meaningless. They focus on the rate of flow from the faucet. But that’s not what matters. What matters is the amount in the tub. If the tub fills up enough, global average temperature will rise more than 2 degrees Celsius and we’ll be in trouble. Avoiding that — staying within our “carbon budget” — is the name of the game.

The second difference is that climate change is irreversible.

Roberts cites a 2009 paper from Nature, "among many others":

The climate change that takes place due to increases in carbon dioxide concentration is largely irreversible for 1,000 years after emissions stop. Following cessation of emissions, removal of atmospheric carbon dioxide decreases radiative forcing, but is largely compensated by slower loss of heat to the ocean, so that atmospheric temperatures do not drop significantly for at least 1,000 years.

Climate change is notoriously tricky to deal with in standard economic terms. Part of it is that, to any normal person, something which is irreversible for 1,000 years sounds at least ten times worse than something which is irreversible for 100 years, if not even worse still.

Economically, though, the two are essentially the same. "Present value" is an economic concept dealing with the fact that money in the future is worth less than money now – because you can always invest money now and have more money in the future. Of course, that assumes long-term growth, which, if we're talking about world-changing events like anthropogenic climate change, might not be a safe assumption.

But the end result of the calculations is that nearly any cost beyond a hundred years into the future isn't worth spending money today to avoid. The intuitive conclusion – that it's worth fighting climate change harder if it will last for a millennium than a century – isn't the case. Assuming growth.

But there are even bigger problems for climate change than that. The vast majority of economic responses to it require calculating a "likely cost", and then applying that to the measures proposed to combat it. So, for example, a properly implemented carbon tax requires a calculation of the damage one tonne of CO2 does to the environment, in order to accurately price in the negative externalities.

Unfortunately, conventional ways of pricing risk rather fall over when considering something like climate change, because it carries a non-zero risk of existential threat. That is, there are proposed mechanisms whereby "runaway climate change" could present a civilisation-ending threat.

How do you price the end of civilisation? One option is to look at the value of everything in the world. It would be quite an accounting task, and one faced by the UK government last year when they had to put a price on Stonehenge to fulfil new bookkeeping requirements. The American government puts the value of the entirety of the US at $110trn, so it seems likely that the value of all the world's civilisations is well into 16 figures.

That's high, but it's countable. The real issue comes when you look at an alternative way of measuring the cost of risk, which is the amount you would pay to prevent it. Presumably, there is no sum which would not be worth spending to prevent the end of civilisation. Any cost would be less than the destruction of everything.

By that measure, then, the damage caused by an existential threat is infinite. But the problem with infinite quantities is that they don't work very well in conventional mathematics. Back to the normal risk accounting: you typically multiply the damage you are risking with the chance it will happen. So we are happy to suffer high risk of low damage – like groping for a glass of water at midnight with the lights off – or low risk of high damage – like driving a car – but not high risk of high damage – like driving a car at midnight with the lights off.

But infinity multiplied by anything other than zero is still infinity. Conventional risk assessment simply falls apart when confronted with something the magnitude of the worst possibilities of climate change.

Note too that it doesn't require the risk to be large. I think the risks of climate change are greater than most, but I also think it's extraordinarily unlikely that it actually would result in the end of civilisation. But can we rule it out with certainty?

The best way to look at it is to compare it to our every day lives. Thousands of people are killed crossing the road every day. To do so carries a non-negligible personal existential threat – that is, you might die. Yet I see people dodging traffic to get to work 30 seconds earlier every day, which suggests that, instinctively, we don't treat the risk of death with as much weight as we perhaps should.

But I think theres a different motivator at work. We know death is bad, and that it's worth doing a lot to try and avoid it; but we also know death can come from any corner. And the same is true of fighting existential threats to civilisation. If we could spend ludicrous sums to eliminate them all, it might be worth it; but who's to say we won't prevent climate change, only to die from an asteroid hit? Or cap our future development by not experimenting with nanotech, only for an angry AI to kill us in our sleep?

Climate change could be very, very bad indeed. But making the important choices about the trade-offs we should make to fight it are hard because, not despite, its seriousness.

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.

Photo: Getty Images
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There are risks as well as opportunities ahead for George Osborne

The Chancellor is in a tight spot, but expect his political wiles to be on full display, says Spencer Thompson.

The most significant fiscal event of this parliament will take place in late November, when the Chancellor presents the spending review setting out his plans for funding government departments over the next four years. This week, across Whitehall and up and down the country, ministers, lobbyists, advocacy groups and town halls are busily finalising their pitches ahead of Friday’s deadline for submissions to the review

It is difficult to overstate the challenge faced by the Chancellor. Under his current spending forecast and planned protections for the NHS, schools, defence and international aid spending, other areas of government will need to be cut by 16.4 per cent in real terms between 2015/16 and 2019/20. Focusing on services spending outside of protected areas, the cumulative cut will reach 26.5 per cent. Despite this, the Chancellor nonetheless has significant room for manoeuvre.

Firstly, under plans unveiled at the budget, the government intends to expand capital investment significantly in both 2018-19 and 2019-20. Over the last parliament capital spending was cut by around a quarter, but between now and 2019-20 it will grow by almost 20 per cent. How this growth in spending should be distributed across departments and between investment projects should be at the heart of the spending review.

In a paper published on Monday, we highlighted three urgent priorities for any additional capital spending: re-balancing transport investment away from London and the greater South East towards the North of England, a £2bn per year boost in public spending on housebuilding, and £1bn of extra investment per year in energy efficiency improvements for fuel-poor households.

Secondly, despite the tough fiscal environment, the Chancellor has the scope to fund a range of areas of policy in dire need of extra resources. These include social care, where rising costs at a time of falling resources are set to generate a severe funding squeeze for local government, 16-19 education, where many 6th-form and FE colleges are at risk of great financial difficulty, and funding a guaranteed paid job for young people in long-term unemployment. Our paper suggests a range of options for how to put these and other areas of policy on a sustainable funding footing.

There is a political angle to this as well. The Conservatives are keen to be seen as a party representing all working people, as shown by the "blue-collar Conservatism" agenda. In addition, the spending review offers the Conservative party the opportunity to return to ‘Compassionate Conservatism’ as a going concern.  If they are truly serious about being seen in this light, this should be reflected in a social investment agenda pursued through the spending review that promotes employment and secures a future for public services outside the NHS and schools.

This will come at a cost, however. In our paper, we show how the Chancellor could fund our package of proposed policies without increasing the pain on other areas of government, while remaining consistent with the government’s fiscal rules that require him to reach a surplus on overall government borrowing by 2019-20. We do not agree that the Government needs to reach a surplus in that year. But given this target wont be scrapped ahead of the spending review, we suggest that he should target a slightly lower surplus in 2019/20 of £7bn, with the deficit the year before being £2bn higher. In addition, we propose several revenue-raising measures in line with recent government tax policy that together would unlock an additional £5bn of resource for government departments.

Make no mistake, this will be a tough settlement for government departments and for public services. But the Chancellor does have a range of options open as he plans the upcoming spending review. Expect his reputation as a highly political Chancellor to be on full display.

Spencer Thompson is economic analyst at IPPR