They are roughly equal problems at the moment.
> Recent estimates show that contrails cause about the same amount of warming each year as all the CO₂ emitted by all flights from 1940 to 2018.
> Recent estimates show that contrails cause about the same amount of warming each year as all the CO₂ emitted by all flights from 1940 to 2018.
For most flights today though, if you only count the CO2 produced you're understanding the climate damage by about half.
We need to do both of course, but contrails should’ve been resolved the moment they were identified as so significant, it’s frustrating how slowly the industry responds to such an enormous opportunity (“we halved our climate impact last year” would be easy marketing)