Myles Allen at COP21
  • 7 December 2015

Climate change is not the most urgent issue facing the world today: which is why the Paris conference matters

Professor Myles Allen presents his thoughts on the COP Climate negotiations. Pictured above at our side event: Metrics of progress towards net zero and the two degree goal - science for a safe climate.

As tens of thousands of diplomats, politicians and activists converge on Paris for the 21st Conference of the Parties (COP) of the United Nations Framework Convention on Climate Change next week, the mood could hardly be more different from that in Copenhagen in 2009. Rallies, marches and open-air meetings have been, understandably, banned; those Heads of State that do turn up will no doubt be taking the opportunity to huddle over migration and terrorism rather than ponder the future of the Anthropocene; and the breathless “12 days to Save the Planet” reporting of six years ago seems like a rather embarrassing dream.

Several Oxford academics are contributing to events at the COP, from meetings of investors concerned about ‘stranded assets’, to a technical briefing on how to measure the impact of different greenhouse gases in ‘Intended Nationally Determined Contributions’. And many more of our students are planning to travel to Paris to make their voices heard somehow on (I hope) rather less esoteric topics.

Last year I was invited to act as the senior academic member of the Oxford Climate Society, an impressive and entirely self-organising group genuinely committed to achieving change, several of whom will be cycling to Paris this week. I naturally support them in this, although with a plea to make as little extra work as possible for the long-suffering French police. Their generation, after all, will feel the impacts of climate change much more than mine: have a look at the interactive we developed with the Guardian to get a feel for the 2013 projections from the Intergovernmental Panel on Climate Change (IPCC). One of the points we make is how little has really changed since the last IPCC Assessment in 2007. The odds on the highest projections have been revised down slightly, but at the same time the impacts of even rather modest levels of warming are becoming clearer.

2015 is shaping up to break 2014’s temperature record by a Usain-Bolt-defying margin, while global temperatures continue to evolve almost exactly as we predicted they would in response to rising greenhouse gases back in the 1990s. Human-induced warming is over 0.9°C already, and if we add in the effect of this year’s El Niño event, annual temperatures look set to surpass 1°C for the first time. Even those who used to argue that climate change would be largely benign up to a warming of 2°C now acknowledge that we may have already reached the level at which the costs outweigh any benefits.

So why the apparent lack of urgency about the Paris talks? As the eminent economist Lord Nicholas Stern asked rhetorically in his recent lecture in Oxford and in the title of his latest book: “Why are we waiting?” As a non-economist, I can’t resist pointing out (and I suspect Nick would agree) that part of the blame lies in traditional economics. I gave a Physics Colloquium earlier this term entitled “How hot does it get in a world run by economists?” and the answer was, well, really rather warm if we use conventional “market” rates of discounting to weigh up the benefits of avoided impacts in the future against the costs of avoiding emissions today. Because carbon dioxide accumulates in the climate system, the marginal benefits of one more puff will always exceed the costs on the environment if we discount the future fast enough.

We published a series of papers back in 2009 drawing attention to this cumulative impact: the fact that climate change is a stock, not a flow problem. Risks, in the long term, are determined by the total amount of carbon dioxide we dump in the atmosphere, not the rate of emission in 2020, 2030 or any other year. And as the Nobel prizewinning economist Michal Kalecki put it: “Economics is the science of confusing stocks with flows.” Climate change isn’t the only problem where this matters: as my colleague Cameron Hepburn observes, lots of awkward consequences (not least politicians’ temptation to run up deficits) arise from the fact that we typically measure economic virility in terms of consumption (a flow), not wealth (a stock). Those 2009 papers appeared too late to have any impact on Copenhagen, but it has been encouraging, over the ensuing years, to see how fast this new way of thinking has been taken up.

The latest IPCC reports could not have been clearer: “Cumulative emissions of carbon dioxide largely determine global mean surface warming by the late 21st century and beyond,” and “mitigation pathways that are likely to limit warming to below 2°C relative to preindustrial levels … would require substantial emissions reductions over the next few decades and near zero emissions of CO2 and other long-lived GHGs by the end of the century.” For one who, I confess, had grown rather cynical about the willingness or ability of the policy community to respond to evolving science, the response has been impressive. The need for net zero carbon emissions to stabilize climate has been acknowledged by lots of governments, our own Secretary of State for Energy and Climate Change, Amber Rudd, the G7, Mark Carney, Ed Milliband, the list goes on.

This matters, because zero is a nice simple number. The problem with the 2009 way of thinking, “one tonne per person per year in 2050” (or whatever), is that it leaves fossil fuel producing companies, and countries, all planning to be the ones selling those tonnes. The great advantage of zero is there is not much point in arguing over how it is shared out. It makes the long-term climate challenge crystal clear: to stabilise climate, we either have to work out how to compensate for fossil fuel emissions by recapturing carbon dioxide back out of the air and disposing of it permanently, or we need to stop emitting it altogether. The chances of “net zero” featuring explicitly in the final Paris text are, I gather from the people who read the tea-leaves on such things, rather remote. This is understandable, given the enormity of the implication for some countries that it might mean them having to leave some of their fossil carbon underground. Expect, at best, a vague acknowledgement of a long-term need for decarbonisation. But one thing the IPCC process has taught me is that governments generally understand a lot more than they are prepared to let on, still less acknowledge formally in an internationally-agreed text. So the fact that “net zero” is even under discussion is clear evidence that the vast majority do understand the point and its implications. Net zero has practical implications far beyond the wording of international agreements. Efforts to stem the flow of carbon dioxide into the atmosphere will be moot unless they are part of a strategy to limit the overall stock of emissions.

So what are the actions we can take today that most increase the chances of the generation of decision-makers represented by those students cycling to Paris achieving net zero when they need to, likely at some point in the second half of this century? If I have a criticism of Nick Stern’s fine book, it is his emphasis on what can be done immediately. In many ways, that is his point: he is writing about measures we can get on with right away without breaking the budget or compromising on the fight against poverty. It is clearly mad that we, as a nation, waste as much energy heating badly-insulated homes as our entire natural gas imports from Qatar. But you don’t need to be concerned about climate change to realise this makes no sense (unless, it seems, you happen to serve in our current government). But we can’t get emissions to zero with better home insulation. Conventional emission reduction measures – carbon pricing, subsidies for low-carbon energy, improved vehicle and building efficiency, and such like – may together achieve reductions of 50%, or even 80% depending on your level of optimism. But getting rid of that last 20% will require much more radical measures: capturing carbon dioxide at source and disposing of it underground or in deep ocean trenches, or even recapturing it back out of the air. Bioenergy may have a major role to play here (it certainly does in most scenarios): plants have, after all, a long track record as a carbon capture technology. But competition with food production over land and water resources may be a major limitation.

So, in the end, the next generation is going to have to invent its way out of this problem. There are things we can do today to make the problem they will have to solve easier, harder or plain insurmountable, but in the end, we still have to provide them with the tools and technologies they will need to solve it. Solving climate change does not necessarily require a radical re-invention of the way we live (although that might be a by-product of the solution). Rather, it requires a much more mundane technical reform of the way we use fossil carbon (a worldwide ban being neither practicable nor ethical). This dawning realisation that the problem is both harder, but also duller, than we thought in 2009, is one of the drivers of the contrast in mood between Paris and Copenhagen. There will be fewer rock-stars in Paris, and that is a promising sign. Rock-stars may help inspire millions to change their behaviour, but we didn’t control cholera in 19th century Britain by changing behaviour (although a discounted cost-benefit analysis in the 1800s might well have suggested that behaviour change was the cheapest way of reducing cholera deaths by 50%, or even 80%, over the next few decades). Cholera was contained by engineers and architects – supported by lawyers and accountants – building sewage systems. We don’t need rock-stars to advise on how to get rid of sewage, and we don’t need them to advise on how to get rid of carbon dioxide either.

Climate change, as an issue, has lost its glamour. And that is a good thing. We needed the rock stars back in the 2000s to get enough people interested to give the politicians the courage to do something about it. But as the first tentative steps are taken, the focus moves on to the “how” rather than the “why” of climate change. And that is, inevitably, more mundane. This is not an issue that will be solved by hyperventilating. So, to the students cycling to Paris: make yourselves heard as best you can, keep safe, and come back to your degrees. Your planet needs your hearts and voices, but above all, it needs your brains.

Solving climate change does not necessarily require a radical re-invention of the way we live. Rather, it requires much more mundane technical reform of the way we use fossil carbon.

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