Human CO2 is only 3 percent of the CO2 that flows into the atmosphere.
by Dr. Ed Berry
(editing in process)
Peter Pollard showed that bacteria in freshwater systems emit about 66 GtC per year, which is seven times the CO2 emitted by human burning of carbon fuels. Freshwater CO2 emissions increase with temperature.
Here are the known annual carbon inflows into the atmosphere.
| Source | GtC per year | Percent of total |
| Land | 110 | 36 |
| Ocean | 60 | 20 |
| Animal – Fungal | 60 | 20 |
| Freshwater | 66 | 21 |
| Human | 10 | 3 |
| Total | 306 | 100 |
Human CO2 is about 3 percent of the CO2 that flows into the atmosphere. Natural processes are about 97% of the total CO2 inflow.
IPCC’s carbon cycle has four major reservoirs – Land, Atmosphere, Surface Ocean, and Deep Ocean – connected in that order by carbon flows in both directions.
IPCC’s data show its natural carbon cycle has these equilibrium percentages for natural carbon in each reservoir:
| Land | Atmosphere | Surface Ocean | Deep Ocean |
| 6.1% | 1.4% | 2.2% | 90% |
Therefore, if human carbon emissions were to stop, human carbon would flow to the same equilibrium percentages as natural carbon has, according to the CEP. That would leave 1.4% of human carbon in the atmosphere.
Human carbon in the carbon cycle is about 1% to the total carbon in the carbon cycle. Therefore, human carbon in the atmosphere would be 1.4% of 1%, or about 3 ppm.
The key point is that natural CO2 inflow is 33 times the human CO2 inflow.