80% of the US lives in "urban" areas (https://en.wikipedia.org/wiki/Urbanization_in_the_United_Sta...), and that's where most of the emissions are from. It's not geography that causes the low density, it's urban sprawl and culture. Eating might not be optional, but living in a car-centric low-density neighborhood definitely is. It's one of the things our ancestors would consider a luxury, and which our ever-comparing north american minds now treat as a basic necessity.
I think it would be super interesting to look at CO2 emission per capita broken down by states (i.e. perhaps states along the coasts would show a very different picture than less populated states).
309 people per mi2 (France) vs 421 for the NY state.
its astonishing how the difference between "live in a city" and "live in the suburbs outside a city" is more than 3:1
Of course there's the open question of whether something like Brookline or even more so Cambridge or Somerville count as "suburbs outside a city".
So if you start out using many times more energy than other countries per capita, you'll struggle to equal them on CO2 emissions even if that's a core policy goal.
The low population density in much of the US drives increased energy usage. I will walk to the nearby grocery store in a few minutes to buy my week's groceries, many Americans will drive, perhaps as much as an hour, to buy their groceries, it's not as though eating is optional. And this low density also forces bad energy source choices (e.g. using wood fires to keep warm seems pretty reasonable when there is no mains electricity out where you live even though of course it's very inefficient)
But to be fair consumerism does not help. Americans have been somewhat resistant to energy efficiency technologies that took off elsewhere, consumption is a sign of wealth and success and so efficiency is in that sense "bad". The entire city of Las Vegas is clearly a terrible idea from an energy efficiency point of view, why would you build a city in a desert?