As mentioned before, the Stern Review cites a figure of five gigatonnes of carbon dioxide equivalent as the quantity that can be sustainably absorbed by the planet each year. Given the present population of 6.6 billion people, that means our fair share is about 750kg of emissions each, per year. Right now, Canadian emissions are about 23 tonnes per person per year. They are highest in Alberta – 71 tonnes – and lowest in Quebec – 12 tonnes. Even in hydro-blessed Quebec, emissions are fifteen times too high.
Everybody knows that emissions in the developed world are too high. The average Australian emits 25.9 tonnes. For Americans it is 22.9; the nuclear-powered French emit 8.7 tonnes each. The European average is 10.6 tonnes per person, while North America weighs in at 23.1. One round-trip flight from New York to London produces the amount of greenhouse gas that one person can sustainably emit in three and a half years. These are not the kind of numbers that can be brought down with a few more wind turbines and hybrid cars; the energy basis of all states needs to be fundamentally altered, replacing a system where energy production and use are associated with greenhouse gas emissions with one where that is no longer the case.
What is less often acknowledged is that emissions in the developing world are already too high. Chinese per capita emissions are 3.9 tonnes, while those in India are 1.8. The list of countries by per-capita greenhouse gas emissions on Wikipedia shows three states where per-capita emissions are below 750kg: Comoros, Kiribati, and Uruguay. Even the average level of emissions for sub-Saharan Africa is almost six times above the sustainable level for our current world population.
And our world population is growing.
All this raises serious questions of fairness. Obviously, people in North America and Europe have been overshooting our sustainable level of emissions for a long time. Do developing countries have a similar right to overshoot? How are their rights affected by what we now know about climate change? If they do have a right to emit more than 750kg per person, does that mean people in developed states have a corresponding duty to emit less than that? Even if we emitted nothing at all, we couldn’t provide enough space within the sustainable carbon budget for them to emit as much as we are now.
The only option is for everyone to decarbonize. The developed world needs to lead the way, in order to show that it can be done. The developing world needs to acknowledge that the right to develop does not trump other forms of legal and ethical obligation: both to those alive now and to future generations. People in both developed and developing states may also want to reconsider their assumptions about the desirability of population growth. Spending a few centuries with people voluntarily restricting their fertility below the natural rate of replacement could do a lot to limit the magnitude of the ecological challenges we will face as a species.