I don't know what kind of string manipulation options unity gives, but the numbers could use commas. By the time the nuclear war option is unlocked, the difference between before clicking it and after clicking it becomes invisible.

This was cool! I enjoyed that it was essentially a race against an ever-growing population on the planet. Once I realized that my harvesting was making the population go down, I wondered what would happen if I could make it go down to zero, and it was oddly satisfying to get to that point.