Earth After The Colonists: The City of Neoterra

Previously on EATC: https://www.reddit.com/r/worldbuilding/comments/5m3q63/earth_after_the_colonists_overview/

About 2,500 years after First Contact and the Human-Colonist War, the surface of the Earth is completely unrecognizable. The eruption of the Yellowstone supervolcano, a short but brutal nuclear war, and "razing" of the Earth's biosphere by the arachnoid Colonists have wiped out the vast majority of Earth's native life. It is only due to a small but vocal group of conservation-minded Colonists that any macroscopic native life remains, and this life is radically modified. The most familar lifeforms are a group of genetically modified sharks, the last known fish in the ocean, and various deep-sea lifeforms modified or evolved to live in more coastal environments. Apart from this neo-Devonian, even neo-Silurian marine ecosystem, the only macroscopic Terran lifeforms on the surface are a few species of hardy lichens, living on coastlines and mountains throughout the world. Otherwise, the terrestrial biosphere is now dominated by alien lifeforms: The sapient, whip scorpion-like Colonists, living in cities resembling fields of gigantic, metallic termite mounds, and their main food source, Funcrop, a fungus-like crop that comes in many variations. Some even photosynthesize to produce supplemental oxygen to Colonist cities, the closest thing to forests in this bizarre new age. To a casual observer on the surface, and indeed the beliefs of the vast majority of Colonists, it would seem that humanity had died out completely.

But this is not the case. Beneath a mountain in Antarctica, close to Mount Erebus and other, smaller volcanoes which supply geothermal energy to the city, the last human city of Neoterra exists. Home to slightly more than 120,000 people, the city is built out of rock and subterranean ice (most surface ice melted with climate change), and augmented with bricks of rock and fungus, and resembles a larger, colder version of subterranean settlements in former Australia. Geothermal energy and small amounts of fusion and hydroelectric power allow electricity to exist, which is used to light the city as well as provide basic needs to homes. With the extinction of agricultural species like corn, wheat, chickens and cows which could never be sustained in Neoterra, the vast majority of food production is by algae grown under lights and various forms of genetically engineered bacteria and fungi, which can produce materials such as vitamins, medicines, and even artificial versions of culinary luxuries such as milk, egg components, cheese and gelatin. Larger fungi are used in the production of building materials, as well as leather and similar clothing materials. Travel is achieved mainly by vehicles resembling tramcars, as the outside streets tend to be cold, comparable to former Alaska during cold (but not the coldest, due to electrical heating) times of the year. Plumbing exists throughout the city, and overall apart from the coldness it is not necessarily a horrible place to live, even having a form of internet. It's just an underground small city.

Apart from humans, microbes, and the farmed algae and fungi, a handful of non-human animal species (apart from the usual microscopic nematode worms and tardigrades) exist in the city, especially in outskirts which are the closest thing humans in Neoterra can consider "nature". Descendants of Belgica antarctica exist even in urban areas, feeding on fungi and coming in several different forms, and these are fed upon by the last non-human tetrapods, namely genetically engineered pseudohybrids of the cold-tolerant Siberian salamander and various species of cave salamander which can live in cold, subterranean environments, made specifically for the caves as a morale boost for humans. A small aquatic morph also exists in small, subterranean bodies of water, feeding on food scraps and Antarctic fairy shrimp. Pseudoscorpions also exist to feed on dust and fungi, the last of the arachnids.

Neoterra was originally built in 2079 by the Australian government in anticipation of a war with the Colonists on their refugee spaceship coming towards Earth, and was expanded for the next seven years in collaboration with the governments of Chile, Argentina and New Zealand. Upon the Human-Colonist War, refugees from various countries of the world were gathered, along with various items and resources, and after the initial 60,000 people entered (along with some long-dead rebel Colonists whose bodies and armory are displayed in the Neoterra Museum as a reminder of the potential threat above), the colony was sealed off for good. No human is likely to have seen the surface, or even sunlight, since then, and as a result the population of Neoterra has evolved a pale skin complexion (despite some African and Polynesian ancestry) and slightly reduced eyesight, though they are by no means on the way to becoming blind troglobytes. Visiting the surface is both forbidden and practically impossible now, as to prevent another Human-Colonist war which the human race would certainly lose (though all Colonist factions have agreed to end all hostility to any surviving humans, they obviously have no way of knowing this). Neoterra has universal basic income, universal healthcare, and is generally liberal apart from a two-child policy; abortions are available on demand, gay marriage is legal, compulsory education for ages 6-15, and recent environmental efforts exist, including an ambitious effort to bring back two surface-dwelling species presumed extinct: The Antarctic pearlwort and the zebrafish, of which near-complete genomic records exist on computers. Any individuals cloned would be kept as pets and laboratory models, though release of modified cold-hardy zebrafish into the "wild" has not been ruled out.

The city of Neoterra has stayed relatively stable for 2,500 years, and shows no sign of imminent collapse. However, Colonists have recently redeveloped advanced satellites. Studies of the Earth's surface from space could well reveal Neoterra's existence under Antarctic rock, and though Colonists are forbidden to actively look for surviving human colonies to destroy, the implications of Neoterra's possible discovery are still unknown.

Hey guys, decided to expand the city of Neoterra a bit in this new post. If you have any questions or suggestions, feel free to ask me.