Replace fossil fuels with nuclear fission and renewables. Build high-speed electric rail systems to replace local flights. Replace freight by bunker oil powered container ships with something else - renewables would be nice, if they can work, but nuclear powered cargo ships have been proven plenty functional. Plentiful power thanks to fission, and electrification of the transport network, would make free public transport for everyone much easier to implement. It would also power desalination plants in efforts to help push back desertification, along with the usual planting of trees etc. Recycling too, since as good for the environment as it can be, it is often energy-intensive. That kind of thing.
Of course, the chances of anyone with significant power and influence actually listening to any of my suggestions is close to nil, so I'm not hopeful that any of that will happen without a lot more trouble occurring along the way.