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.

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We still have time to change our minds on Brexit

The British people will soon find they have been misled. 

On the radio on 29 March 2017, another "independence day" for rejoicing Brexiteers, former SNP leader Alex Salmond and former Ukip leader Nigel Farage battled hard over the ramifications of Brexit. Here are two people who could be responsible for the break-up of the United Kingdom. Farage said it was a day we were getting our country back.

Yet let alone getting our country back, we could be losing our country. And what is so frustrating is that not only have we always had our country by being part of the European Union, but we have had the best of both worlds.

It is Philip Hammond who said: “We cannot cherry pick, we cannot have our cake and eat it too”. The irony is that we have had our cake and eaten it, too.

We are not in Schengen, we are not in the euro and we make the laws that affect our daily lives in Westminster – not in Europe – be it our taxes, be it our planning laws, be it business rates, be it tax credits, be it benefits or welfare, be it healthcare. We measure our roads in miles because we choose to and we pour our beer in pints because we choose to. We have not been part of any move towards further integration and an EU super-state, let alone the EU army.

Since the formation of the EU, Britain has had the highest cumulative GDP growth of any country in the EU – 62 per cent, compared with Germany at 35 per cent. We have done well out of being part of the EU. What we have embarked on in the form of Brexit is utter folly.

The triggering of Article 50 now is a self-imposed deadline by the Prime Minister for purely political reasons. She wants to fix the two-year process to end by March 2019 well in time to go into the election in 2020, with the negotiations completed.

There is nothing more or less to this timing. People need to wake up to this. Why else would she trigger Article 50 before the French and German elections, when we know Europe’s attention will be elsewhere?

We are going to waste six months of those two years, all because Prime Minister Theresa May hopes the negotiations are complete before her term comes to an end. I can guarantee that the British people will soon become aware of this plot. The Emperor has no clothes.

Reading through the letter that has been delivered to the EU and listening to the Prime Minister’s statement in Parliament today amounted to reading and listening to pure platitudes and, quite frankly, hot air. It recalls the meaningless phrase, "Brexit means Brexit".

What the letter and the statement very clearly outlined is how complex the negotiations are going to be over the next two years. In fact, they admit that it is unlikely that they are going to be able to conclude negotiations within the two-year period set aside.

That is not the only way in which the British people have been misled. The Conservative party manifesto clearly stated that staying in the single market was a priority. Now the Prime Minister has very clearly stated in her Lancaster House speech, and in Parliament on 29 March that we are not going to be staying in the single market.

Had the British people been told this by the Leave campaign, I can guarantee many people would not have voted to leave.

Had British businesses been consulted, British businesses unanimously – small, medium and large – would have said they appreciate and benefit from the single market, the free movement of goods and services, the movement of people, the three million people from the EU that work in the UK, who we need. We have an unemployment rate of under 5 per cent – what would we do without these 3m people?

Furthermore, this country is one of the leaders in the world in financial services, which benefits from being able to operate freely in the European Union and our businesses benefit from that as a result. We benefit from exporting, tariff-free, to every EU country. That is now in jeopardy as well.

The Prime Minister’s letter to the EU talks with bravado about our demands for a fair negotiation, when we in Britain are in the very weakest position to negotiate. We are just one country up against 27 countries, the European Commission and the European Council and the European Parliament. India, the US and the rest of the world do not want us to leave the European Union.

The Prime Minister’s letter of notice already talks of transitional deals beyond the two years. No country, no business and no economy likes uncertainty for such a prolonged period. This letter not just prolongs but accentuates the uncertainty that the UK is going to face in the coming years.

Britain is one of the three largest recipients of inward investment in the world and our economy depends on inward investment. Since the referendum, the pound has fallen 20 per cent. That is a clear signal from the world, saying, "We do not like this uncertainty and we do not like Brexit."

Though the Prime Minister said there is it no turning back, if we come to our senses we will not leave the EU. Article 50 is revocable. At any time from today we can decide we want to stay on.

That is for the benefit of the British economy, for keeping the United Kingdom "United", and for Europe as a whole – let alone the global economy.

Lord Bilimoria is the founder and chairman of Cobra Beer, Chancellor of the University of Birmingham and the founding Chairman of the UK-India Business Council.