Equal historically
Historically equal
This would mean taking into account how much has been emitted since we started burning significant amounts of fossil fuels in 1880 and sharing equally per person on that basis. A minority of countries (UK for example) have used a disproportionately large share of the fossil fuel reserves since the industrial revolution . And we have benefitted economically from these “Historical emissions”. Objectively this is the fairest approach but it is already far too late to do this. The USA, UK, Germany and Russia have all emitted far more than their total fair share. This graph from “Sustainable Energy without the hot air” by David MacKay shows each country’s cumulative emissions of CO2, expressed as an average emission rate over the period 1880–2004.
If we take the total emissions allowed by the IPCC and divide by the global population in 2004 (6.4 billion) then we can mark on the graph the levels for staying below 1.5, 2 and 3˚C, see below:
So we have already burnt more than double our fair share in the UK to stay below 2˚C.