Harvesting the Biosphere (Vaclav Smil, 2012) examines a single question in great detail: "what is the carrying capacity of the planet?" How many of us can it support?
Photosynthesis is nature's great freebie. Earth is a closed system and sunshine is our only input (besides a bit of tidal energy). This means everything in the food chain traces back to plants. So, to answer the question of carrying capacity, the book quantifies 2 things:
- How much phytomass (photosynthetically-created biomass... i.e. "plants") can the planet produce?
- How much phytomass do we consume?
- Farming and population density: improvements in farming method dramatically increased the carrying capacity of the planet, from 1 person/km to 1400 people/km.
- The phytomass needed to meet basic human needs can be categorized as: food, feed, fiber and wood.
- Forests make up 90% of land phytomass.
- TODO this section under construction
Misc Interesting Threads
- Things eating other things is energy lossy, so lots of energy is wasted along the food chain. This means the total biomass of things at the top of the food chain is very tiny compared to the biomass of short-lived micro-organisms.
- Temperate ecosystems have been studied more much more intensively than tropics.
- The deep open ocean is cold and nutrient-poor... the equivalent of a desert.
- Old-growth forests continue to produce phytomass and capture carbon (Luyssaert 2008).