Kidou Senshi Gundam Eight

Earth, the third planet in the solar system. Countless years have passed since humanity's birth. Great advances in science, biology, and technology were supposed to have freed mankind from strife and suffering, bringing peace and prosperity. But in the year 2030, Earth, once humanity's cradle, is on the verge of human extinction.

Survivors: 258.

Gundam: One.

(Source: Kadokawa, translated)