I keep saying this and getting downvoted for it, but there isn't any magic bullet technology fix. Even if commercial fusion were magically deployed at scale today, there's still too much CO2 in the air, still too many petrol vehicles on the road. The only way we stand a chance is by making sweeping, society-wide changes.
The only thing you as an individual can do is try to pressure your leaders for large scale government activity.
https://www.sunrisemovement.org/
To answer your question "Are there any people who are actively working on fixing the environment?"
Basically, to a rounding error, the answer is "No". You can see for yourself here: https://climateactiontracker.org/ National responses range from "critically insufficient" to merely "insufficient".