I went to primary school (1-4 grade) in the mid 1990s in a small post-communist country. Fossil fuel burning producing emissions bad for your health and harming the planet was something that was a part of the curriculum in like the second or third grade (I remember it vividly because the teacher asked why are trolleybuses better than bused, I was sure it was something to do with the engine, but didn't want to risk embarrassing myself; I was right, and I told myself I should be more confident in myself).

If it managed to get into the curriculum of a small post-communist country in the mid-1990s, "green" organisations should have been aware of the impacts of emissions and CO2. And for what it's worth, Greenpeace up until the Russian invasion of Ukraine made it infeasible, was pushing for closing of actively running and already amortised nuclear power plants and replacing them with gas.

It's hilariously ironic how one of the most iconic green movements actually ended up causing more damage to the planet on the planetary scale than helping. Sucks for us all that have to live with it though, just because a bunch of blind idiots couldn't be bothered to think.