we have all sorts of compounding effects. It's still an atmosphere mostly made of nitrogen, on a scale vastly exceeding 2000 years. I don't have an intuition

we have all sorts of compounding effects. It's still an atmosphere mostly made of nitrogen, on a scale vastly exceeding 2000 years. I don't have an intuition for how molecules actually disperse, but I do know that general climate trends certainly aren't "random dispersion". Big volcano eruptions make for pretty sunsets across the world. Nuclear testing fallout is detectable in everything since atmospheric nuclear testing began. Everywhere we find the K-P boundary, we find iridium. The counter-assumption (which may well be true!) is the counter-intuitive one.