What??? The earth doesn't care about "per capita". What matters is the total amount put into the atmosphere. Here are some numbers from 2017. This shows that the US can't do it alone.
The comment you'll often hear in Europe is that there's not much point to all the things we're doing if the US continues to do very little.
The US government is responsible for the 4% of the world's population who make up 14% of the emissions (and, Americans, like Europeans, are also indirectly responsible for a significant part of China's emissions.)
The only countries that didn't ratify the Kyoto protocol are Sudan, Afghanistan and the USA. The only way the problem gets solved is by the whole world agreeing to take action. The Chinese and Indian governments do at least accept the need to reduce Carbon emissions, whereas the current US government is promising to withdraw from the 2016 Paris agreement in November.
The idea that the US 'cannot do it alone' would be hilarious if the consequences weren't such a big deal.