Earlier quoted context omitted.
> The bottom 85% (in income terms) of the global population contribute very little to unsustainability. Is that true? What percent do they contribute?
This should give you a rough idea. https://www.overshootday.org/newsroom/country-overshoot-days... > Not all countries will have an overshoot day. By way of the country overshoot equation above, a country will only have an overshoot day if their Ecological Footprint per person is greater than global biocapacity per person (1.63 gha). There’s a lot of countries not listed, i.e they do not overshoot.
A person's ecological footprint is a multifaceted thing for which I think a single number cannot necessarily provide a very meaningful summary.
But here's some other data, that considers only CO2 emissions: https://www.ucsusa.org/resources/each-countrys-share-co2-emi...
It groups by country rather than income level but, reading between the lines, it seems to me almost certain that the bottom 85% (in income) of people emit more than half of the global total.
BTW it is important to consider that a large fraction of the emissions from countries like China and India are in the service of consumption in wealthy western countries. But, I googled, and even in a famously export-heavy country like China, exports only account for 17% of the GDP.