Could a planet like Coruscant exist? The surprising answer is maybe, and it would sort of be like Hong Kong spread all over the world. If we assume continued food production improvements as seen over the last 50 years, we could carry around 73 billion people on Earth in 100 years and 640 billion in 200 years. Calculations below.
Note the following:
- Earth has a land area of 148 million km.
- Hong Kong has an area of 1104 km2. Of this total, about 70% (773 km) is not used by humans (woodlands, farms), and 331 km is used by humans or otherwise unusable. The large majority of Hong Kong's land area is steep tropical vegetation prone to flash flooding and landslides, making it historically difficult to build on. This is why it has not been completely built over, and it is now strictly protected.
- Hong Kong has a population of 7.188 million. The overall population density is 6510 people per km, or 21716 people per km if you only count the land used by humans.
If Hong Kong was scaled up to the Earth's total land area, the world would have a population of 970 billion people - almost exactly the 1 trillion on Coruscant. Hong Kong is pretty packed, but most people there do have a reasonable quality of life by global standards. But we're obviously going to run out of food really fast unless we get some magical new farming technologies. So what would be feasible in the reasonable future?
- About . ; i.e. 16 million km
- Right now, we have about , worldwide. The world produces around 10% more food than it needs, so in a decade or so we might really need only 0.2 Ha per person using near-future farming technology. Food production efficiency has improved by around 2/3 over the past 50 years - if this trend continues, we might need 0.022 Ha per person in 100 years. In 200 years, it might be down to 0.0025 Ha/person.
This means that if we use all available arable land and assume continued improvements in food production capacity for another century, we could feed around 73 billion people in 100 years and 640 billion people in 200 years.
How much space would we need to house the people? AroundIf all of this area was converted into Hong Kong, we would have a global population of 29 billion people. If we convert non-arable land into human habitat, we will still have enough land left. And that's before we start looking to the oceans for large-scale food production and living space, which happens quite a bit in Hong Kong via land reclamation. Some parts of the world's land mass would be unpopular for humans (extreme altitude or cold or desert), so it is quite likely that extensive land reclamation would occur in desirable climate zones.
Note: This quick calculation ignores all of the obvious environmental issues with scaling up the global human population to such massive levels, and says nothing about how we might achieve such huge increases in food production efficiency. It's just intended to show what might be technically possible, given sufficient technology and organization.