I'm not sure I come to that conclusion. At least, that's not how I think about responsibility.
I'd say that per capita emissions is a reasonable measure of scoring how much a country and its people are doing to make climate change worse (or better). And, while not perfectly so, it does a reasonable job as being an actionable metric for how sustainable a country's standard of living is. "America (14.4 t/cap/yr) should try to be more like Japan (8.6 t/cap/yr)" is a reasonable take on how the US can reduce its per-capita emissions, and what changes might take it there. "America (4.8 Gt/yr) should try to be more like the United Arab Emirates (220 Mt/yr)" ends up being rather bad advice.
And while the standard of living in Iceland is quite nice, I doubt that there's any practical way that either China or the United States could reduce their emissions to that level (3.5 Mt/yr) in the short term without millions of people starving to death in the process. It wouldn't be realistic or fair for Iceland to demand that the US cut its emissions to Icelandic levels on an absolute basis (but very fair and reasonable to demand that the US cut to Icelandic levels on a per-capita basis).
In terms of how much responsibility a government has, well... certainly governments that govern more people do have more leverage, and with larger total emissions, there are more opportunities to cut. But if there is any non-zero level that we may consider an acceptable emissions target, surely this level should be proportional to a country's population. And when it comes to international agreements, it's reasonable to ask China and India to make cuts, and it's very reasonable for China and India to say "OK we'll make cuts, but we expect small rich countries like Canada to pull their weight, and if they don't, we won't either".
And when that happens, per-capita emissions is the only sensible way to gauge if those countries are pulling their weight.
There are, after all, a lot of countries, and while the top four (China, US, India, Russia) emit 57% of the total, the rest emit the other 43% of that total, with no single country among them emitting over 2.9%. Even cutting China, the US, India, and Russia's emissions to zero would only cut global emissions in about half, and that's really still not enough to solve the problem, so the little countries will have to pitch in.
I'd say that per capita emissions is a reasonable measure of scoring how much a country and its people are doing to make climate change worse (or better). And, while not perfectly so, it does a reasonable job as being an actionable metric for how sustainable a country's standard of living is. "America (14.4 t/cap/yr) should try to be more like Japan (8.6 t/cap/yr)" is a reasonable take on how the US can reduce its per-capita emissions, and what changes might take it there. "America (4.8 Gt/yr) should try to be more like the United Arab Emirates (220 Mt/yr)" ends up being rather bad advice.
And while the standard of living in Iceland is quite nice, I doubt that there's any practical way that either China or the United States could reduce their emissions to that level (3.5 Mt/yr) in the short term without millions of people starving to death in the process. It wouldn't be realistic or fair for Iceland to demand that the US cut its emissions to Icelandic levels on an absolute basis (but very fair and reasonable to demand that the US cut to Icelandic levels on a per-capita basis).
In terms of how much responsibility a government has, well... certainly governments that govern more people do have more leverage, and with larger total emissions, there are more opportunities to cut. But if there is any non-zero level that we may consider an acceptable emissions target, surely this level should be proportional to a country's population. And when it comes to international agreements, it's reasonable to ask China and India to make cuts, and it's very reasonable for China and India to say "OK we'll make cuts, but we expect small rich countries like Canada to pull their weight, and if they don't, we won't either".
And when that happens, per-capita emissions is the only sensible way to gauge if those countries are pulling their weight.
There are, after all, a lot of countries, and while the top four (China, US, India, Russia) emit 57% of the total, the rest emit the other 43% of that total, with no single country among them emitting over 2.9%. Even cutting China, the US, India, and Russia's emissions to zero would only cut global emissions in about half, and that's really still not enough to solve the problem, so the little countries will have to pitch in.