For the better part of two decades, international climate policy has held industrialized countries responsible for the world’s carbon habit. But today developing-country emissions make up more than half the world’s total and are climbing faster than emissions in the wealthy North. A paper just out in PNAS offers a new argument that aims to bring these troubling emissions into the fold of a global climate deal – while preserving a sense of equity and the right of the planet’s poorest to seek prosperity.
The work comes from Princeton’s Shoibal Chakravarty and a team of colleagues including Stephen Pacala and Robert Socolow, who previously brought us the handy concept of stabilization wedges. The principle: instead of asking the wealthiest nations to shoulder the burden of greenhouse gas cuts, ask the wealthiest individuals in both developed and developing countries to do so.
They aren’t suggesting that the UN hand out carbon ration cards or ground private jets. Instead, nations would be given emissions targets based on how many high-earning, high-emitting citizens they have. That means that although developed countries would still have to cut their emissions most quickly, developing countries with a growing middle class, such as China, would also be required to veer away from business as usual.
While Reuters headlined their story “New climate strategy: track the world’s wealthiest”, Scientific American hits the real bottom line with “Who’s to Blame? Making Poor Nations Share the Cost of Fighting Climate Change”. Socolow says, “I think the world understands that … the size of the job required and the speed at which we have to proceed is incompatible with a further granting of a free pass to the developing world.”
But for those countries to relinquish their free pass, they would have to see the burden sharing as fair. That’s where the paper’s economic formula comes in.
Take a country at any point in the future, say the authors, and you can estimate how its projected greenhouse gas emissions are distributed among its citizens by assuming that people with higher incomes emit more. You then put all these high and low emitters of the world into a single distribution and chop off the top of the curve (see right) – taking out a bigger or smaller section depending on how much gas you want to exclude from the atmosphere. This yields a recommended ceiling on individual emissions – in this example, about 10.8 tons CO2 per person per year – that applies equally to all countries. To then come up with a national target, follow the cartoon below.
The authors also try a scenario with an added twist: an emissions floor as well as a ceiling. The idea here is to alleviate extreme poverty by letting people who are now using less than, say, a ton of CO2 per year come up to that low level. The group at first had doubts about this complication, says Socolow, “but we found that if we allow fossil fuels where they’re useful, the extra work that the rest of us have to do is very small.”
Their example ceiling of 10.8 tons holds the world’s emissions at 30 gigatons per year in 2030 – about the same level as seen today. The group emphasizes that this target does not correspond to a goal of stabilizing greenhouse gases at 450 parts per million or any other particular concentration; in other words, it’s not based on scientific warnings about what is needed to avoid severe impacts. It is chosen, rather, to show what rapid coordinated action worldwide could look like. Essentially, the paper provides a formula not for saving the planet but for answering the question, If my country commits to a certain cut, what can we rightly expect from others?
The one billion people expected to be emitting more than 10.8 tons each in 2030 are divided just about equally between the US, other developed countries, China, and remaining developing nations. As a result, when you look at required cuts relative to business as usual, China and the US would have to eliminate the most gigatons. See the chart below: the relevant bar is the third in each cluster, with the purple top segment of the bar showing business as usual in 2030 (with global emissions at 42 Gt) and lower segments showing emissions allowed under increasingly ambitious global targets. In the key, 35 is global emissions of 35 Gt, 30 is 30 Gt, and so on. The fourth bar for each country shows slightly deeper cuts required to provide an emissions floor for the world’s poorest – scenarios denoted ‘P’ in the key. The last bar shows what it would look like to achieve these targets with equal per-capita emissions, which some say will be the fairest long-term solution.
As if by magic, when this is translated to percentage emissions cuts relative to recent years, what emerges for the US and China is a not-bad reflection of what they’ve said they’re willing to do. (Table 1 in the paper has these figures for a 30-Gt target in 2030, whereas most national policies use 2020 as the mid-term milestone; if you want to compare apples with apples, see the wide array of scenarios calculated for 2020 in the supplementary material.) The climate bill that’s now moving into the US Senate requires a 17% cut from 2005 emissions by 2020; taking a scenario from the supplementary material where the US in 2020 cuts 12.9% from 2003 emissions, China would be allowed to more than double its 2003 emissions, but would still have to stay 5% below a business-as-usual baseline. That’s the kind of cautious commitment that Beijing is most likely to embrace, given its domestic policies on greening the national economy. Whether it could possibly be enough to avert dangerous climate change is another question.
Various wrinkles will be raised if such targets come to the debating floor. John Connor from NGO The Climate Institute tells ABC News that the plan “conveniently side-steps” the issue of “historical responsibility”, for example. In fact the authors themselves note this omission and say its one of several considerations that could lead to tweaking the numbers. As a starting point, though, this particular mix of idealism and pragmatism might prove appealing.
But given the December deadline for drafting a climate treaty, is there still enough time for a shift in perspective? Socolow points to the fast pace of change this year: “We moved very fast from Obama’s inauguration to the passage of a piece of legislation – imperfect as it is – in four months. [The US] is clearly becoming much more forthcoming, and China’s much more forthcoming, than I think most people expected. Copenhagen is not too soon for major steps toward a global deal.”
Anna Barnett
All images courtesy of PNAS.