Contrails have a strong “effective radiative forcing” effect. This basically measures the net change in energy flow at the top of the atmosphere: and that change in energy flow dictates how much warming is needed at the surface to offset it. But, this warming effective is very short-lived. If we were to stop contrails today, the warming effect would disappear within a day or so.
Think of it like a very brief but strong pulse of energy.
CO2, on the other hand, has a smaller effect on radiative forcing, but once you emit it, it stays there for centuries or more.
...
[...] we could get rid of around half of the warming impact — maybe slightly less — from aviation, if we were to tackle contrails. The impact would be almost immediate.
...
[...] What tackling contrails now would do is slightly reduce the rate of warming (and therefore do something reduce the risks of nearer-term feedbacks that could affect the release of CO2 from natural systems, and also affect long-term temperature change). It is not an excuse or a substitute for finding a way to decarbonise jet fuel.
....
Contrails with a strong warming impact mostly form in thin regions of the atmosphere, which are cold and humid. If planes fly through these zones of atmosphere, contrails are much more likely to form.
The solution, then, is for some planes to take a short detour to avoid them.
From the article:
...
...
....