https://ourworldindata.org/co2-and-other-greenhouse-gas-emis...
The US is responsible for 25% of cumulative emissions.
Still #1, but to be 'mostly' responsible it would have to have emitted more than double the total which it actually has.
The thesis is for us to get there, we need to increase CO2 output, not reduce it. Let's think about how much CO2 investment would be required to fulfill these projects in the "Green New Deal":
* Coast to coast high-speed rail.
* Retrofitting all major buildings in the USA with better technologies.
* Decommissioning dirty power plants.
* Building nation-wide wind and other green power generating infrastructure.
And we should put our foot on the gas for new green energy research. Inventing better and more efficient technologies has the benefit of reducing global CO2 output.
ftfy.
The truth is that we could reduce emissions by living less affluent lifestyles, like, say, the 1950s. Smaller houses, fewer per capita miles driven, little or no intercontinental or transcontinental flights, less meat. But we won't. We cannot step off the hedonistic treadmill, even for a second, or the economy will collapse. And we can think of nothing worse than the economy collapsing. So we create a false dilemma, an impossible constraint system. So we will fail.
The incredible irresponsibility here really earns the downvotes.
As other commenters pointed out, the US still #1 in cumulative emissions, so the warming we see today and for the next ~10 years is mostly due to the US. Second, the US is absolutely terrible when it comes to per-capita emissions. This is not an example for the world to follow. There is zero moral high ground in telling developing nations to cut emissions and yet gluttonously continuing BAU. If they follow the same carbon intensity curve, the planet is absolutely f*ed. The US and western countries have an obligation to demonstrate how to run a complex developed economy with low, or eventually, no emissions.