A group of researchers led by Australian National University’s Climate Change Institute has come up with an “elegant formula” for dividing up the carbon budget that will still be available if nations agree to limit average global warming to 2°C or 3°C above pre-industrial levels.
“Even agreeing on how big that pie is to begin with is a sensitive topic,” Phillips writes, and “mere mention of a carbon budget has been seen as too sensitive to be [included] in any international agreement.”
The formula points toward a solution by modelling two extremes—an “inertia” option, in which emissions quotas are based on countries’ current rates, and an “equity” scenario, where countries receive per capita emission allowances. Neither is a realistic option for a global climate agreement.
But “at the midpoint between inertia and equity, at which the fairness variable is precisely half-way between the two extremes, something curious happens,” Phillips explains.
“Once you crunch the numbers, a compromise appears much more achievable, even if the task for the world as a whole remains gargantuan. Poor countries still get much more forgiving reduction targets and over longer periods than they would under pure inertia, but wealthy countries now do not have to commit to anywhere near the same high reduction rates.”