Huh?

There are plenty of systems where the difference between 0.04% and 0.03% is dramatic, after all it’s an increase of 30% — and what matters is not the paltry decimal representation but rather the effects.

For example: consider concentration of sodium in human blood. The normal range is 0.31%-0.33% by weight. By 0.4% you’re pretty much dead.

Or consider chromium, an essential trace element: the normal amount is practically infinitessimal, in blood it’s 0.0000007% by weight, approximately. But not enough and you end up with diabetes or cardiovascular disease.

“0.04% vs 0.03%” is not an effective takedown of global warming.

Exactly. Represented as decimal numbers, we could also say that is only 0.0004 vs 0.0003, which looks like even less. Seeing that there is a 30% difference is the important thing here.