no raindrop is responsible for the flood. geographic features and atmospheric systems create floods

Half of Earth’s population is alive thanks to nitrate fertilizer,

Only if you count the animal torture industry in "the population". More protein is spent keeping cows alive than humans.

Some people demand a shitload more than others though. The average car burns 1 m³ of petrol each year. I burn none with my bike.

Then you have people who demand large meat portions in every single meal. I am quite happy to eat oats.

Some are raindrops, others are buckets. Then you have private jet owners... Heavy carbon taxes could help, or some kind of overall environmental harm calculation for it. If you actually care about the poor and don't just want to use them to defend your own life of luxury, its pretty easy to subsidise or reduce rate for essentials that overall rich or poor buy in similar quantities anyway. Its luxuries that the rich buy a lot more of and the poor dying more from pollution.