Geoengineering is often considered "not on the table", but quite possibly is the most tractible solution we have to climate change. Some people imagine Human extinction before imagining geoengineering.

Decaying Dams: Many dams worldwide are aging and might be structurally unsound, yet they still hold vast amounts of water.

Gene editing: Lots of people are dying from horrible recessive gene diseases, which we have the solution to.

The SLOSS debate in conservation ecology.

spilled asteroid dust