Er, I screwed that up. China emits 11 gigatonnes. The US emits ~half that. So more like 800 billion or 4% of GDP. About what we spend on Medicare. Of course,

Er, I screwed that up. China emits 11 gigatonnes. The US emits ~half that. So more like 800 billion or 4% of GDP. About what we spend on Medicare. Of course, even if US emissions went to zero, it wouldn't be enough to stop global warming. So there's that.