The qualifier "for 100k years" Is a little silly. Since the oxygen is in the form of oxides that need splitting, there's no reason the CO^2 can't be recycled i

The qualifier "for 100k years" Is a little silly. Since the oxygen is in the form of oxides that need splitting, there's no reason the CO^2 can't be recycled in the same way. So a small amount of oxygen can be recycled indefinitely, if you have the energy to do so. Food is the same. Both require small amount of material to sustain humans, and recycle indefinitely via solar energy. The difficulty comes from sourcing building/construction materials, i.e. metals via moon-mining.