ton of coal (which is what you might use to heat a house over a year).
Now imagine everyone on the planet burning one ton of coal per year:
that’s 6 Gt C per year, because the planet has 6 billion people.

Where is the carbon?

Where is all the carbon? We need to know how much is in the oceans, in
the ground, and in vegetation, compared to the atmosphere, if we want to
understand the consequences of CO2 emissions.

Figure 31.2 shows where the carbon is. Most of it – 40 000 Gt – is in
the ocean (in the form of dissolved CO2 gas, carbonates, living plant and

Figure 31.2. Estimated amounts of carbon, in gigatons, in accessible places on the earth. (There’s a load more carbon in rocks too; this carbon moves round on a timescale of millions of years, with a long-term balance between carbon in sediment being subducted at tectonic plate boundaries, and carbon popping out of volcanoes from time to time. For simplicity I ignore this geological carbon.)