I walk in the rain each year to remember what happened the day the world changed. The day the DuPont plant exploded in Indonesia and released a chemical solvent that reacted with water vapor into the atmosphere.
The solvent turned water vapor to hydrochloric acid, and more of itself. It only worked on water vapor. Like the clouds.
The world named that day “Ultimate Decimation Day”, the day one in every ten people died. 700,000,000 people. They were the lucky ones.
Billions suffered chemical burns. Rain got in their eyes, burning them. It got in their lungs, scarring them. And thanks to the water cycle, our chemical solvent was slowly replacing all the water on Earth. It was slowly killing the plants and animals.
Bacteria, with their short life cycles, might evolve immunity to the rain. Might. We wouldn’t. Ultimate Decimation Day was the day we all died.