Polluton - nuke and water and solar and wind only, impose tariffs on cars
Food - reduce wastage, rooftop and wall gardens, develop efficient farming methods, dramatically reduce meat and dairy consumption
Water - use less by imposing rations etc, and convert salt water
Population - 1 child limit, encourage adoption by lowering fees, make better and cheaper birth control (a shot that makes you infertile for a year maybe?)
Many would say those are radical ideas. But many are incapable of understanding, or choose not to understand, the scope of the problems we face.
Changing 100% of our energy to renewable sources is something we'll have to do eventually. But it'll take one hell of an upheaval for it to happen. Imposing tariffs on cars is, IMO, a bad idea. Drivers are already taxed and otherwise charged through the roof.
I agree that we need to reduce meat consumption. The Western world already consumes far too much red meat for its own good. It's also scary that most of the Western world doesn't know how to grow its own food, thereby making things hairy if (when) a disaster strikes.
Rationing of water helps to an extent if its enforced. Converting salt water to drinkable water is bloody expensive, resource-intensive and as such not a viable strategy...yet.
Very few would stand for a 1-child limit in the Western world, and they'd point at China and shout "patriarchy!" at the top of their lungs. We should 100% be encouraging adoption...there should be no fee whatsoever.