Global carbon stocks by broad source 2010-2019

In total, there is over 122,600,000 gigatons (one gigaton = one billion metric tons) of carbon between the earth's lithosphere (continental crusts and upper mantle) and atmosphere. The vast majority of this is stored in the lithosphere itself, and plays very little role in the global carbon cycle. Over 40,000 gigatons of the world's carbon stock is stored in the ocean. The majority of this is comprised of dissolved inorganic carbon, which includes carbon dioxide, carbonic acid, and carbonate, among other forms, that has dissolved or been absorbed into water - and this accounts for around 95 percent of the ocean's total. The other five percent found in the world's oceans is made up of sediment that has sunk to the surface of the ocean floor, as well as organic matter. Below the earth's surface, between 1,000-2,000 gigatons is stored in fossil fuel reserves, while around 3,500-4,750 gigatons is stored on the earth's surface in permafrost, soil, and vegetation.

In relation to climate change, the volume of carbon in the earth's atmosphere is the most pressing issue. There are approximately 860 gigatons of carbon in our atmosphere, however an imbalance in the earth's carbon cycle means that there is a surplus 5.1 gigatons of CO₂ added each year. The major sources for this are the burning of fossil fuels and land-use conversion (deforestation), which are also depleting the amount of carbon stored on land and below the earth's surface. Additionally, rising temperatures are causing the planet's permafrost to thaw, which not only releases a significant amount of CO₂ into the atmosphere, but also methane and other greenhouse gases.