In the opening scene of American writer Kim Stanley Robinson’s “The Ministry for the Future,” a heat wave combined with a breakdown of the electrical grid in India kills 20 million people. The devastation causes the world’s nations unite to combat climate change.
The claim is probably about historic cumulative emissions which the US exceeds China by 1.5 times
This IMO more accurately represents a countries contribution to climate change then the current years emissions since the CO2 from the past is largely staying in the air, heating the planet.