Question

What are the four main reservoirs of carbon

Answer 1

atmosphere, terrestrial biosphere, oceans and sediments.

Answer 2

There are four major reservoirs, or stocks, of carbon on Earth: 1) in rocks (this includes fossil fuels), 2) dissolved in ocean water, 3) as plants, sticks, animals, and soil (which can be lumped together and called the land biosphere), and 4) as a climate-warming gas in the atmosphere.