[2022] Cap on pollution absorbed by trees?

The setting is found in EcoSim.eco, it's called "MinCO2PerDayFromPlants": -500.0.
The point of it is a limitation for users that insist to use bigger worlds than recommended and hence will not experience lots of ecological threat - this limit at least migitates that somewhat, otherwise the value would be extreme on big worlds not suitably chosen for a challenge depending on the amount of players.

Unfortunately, I don't think that is possible. There generally is no need to do so, though, when playing on one of the recommended and supported map sizes.