Possibly you (well, some international body) can do that. Leaving that idea aside, countries matter because countries are controlled by policies, per-country.

This doesn't, of course, mean that you get to burn a big bonfire of coal if your country has a small population. The reality is that you get to burn a big bonfire of coal in any country unless it has a law against it. And another part of the reality is that emissions are caused mainly by transport, power generation, industry and construction, all of which can be decarbonised by policy, so the personal carbon footprint thing just isn't relevant because it's not up to individuals, and people having orgiastic fossil fuel bonfires is not the true nature of the problem anyway.