So, if magically, all coal burning (other than for steel production) were replaced with NG, the 1200 million metric tons of CO2 would drop to about 800 million tons.
It would be difficult to replace that capacity with "wind and solar" quickly (or nuclear of course).
A crash program to build more nuclear plants to replace all coal fired plants could make a dent in ten years if funded (expensively) and tolerable to the public (not) and based on a single plant design.
There are two new reactors under construction down here, but that is it for nuclear in the US, and old plants are being decommissioned.
The global CO2 emissions are about 40 billion metric tons per year. So, if the US replaced all coal with something carbon neutral, that would drop to about 37.8 billion tons, which isn't enough to offset the growth in global CO2 emissions.
That sort of highlights the main issue here, the shear scale of CO2 emissions globally, and the upward trend that is going to continue despite whatever papers are signed. China and India are supposed to cap by 2030, but that simply isn't nearly enough.