En-en adult card 11 concentration of co2
Card #11: Concentration of CO2
About half of our CO2 emissions are captured by natural carbon sinks.
The other half remains in the atmosphere ; the concentration of CO2 in the air has increased
from 280 to 410 ppm (parts per million) in 150 years.
CO2 measurements have been taken since 1958 in Hawaii, on Big Island, on the flanks of the Mauna Loa volcano. They were initiated by Charles Keeling. In the blue scenario (2°C) they increase until 2040-2050, then they decrease because emissions will have been reduced so much that natural sinks no longer absorb them.
- Carbon sinks It can be argued that CO2 emissions take place before reaching carbon sinks. But the opposite link has our preference.
- Ocean acidification Players often identify CO2 concentration as a cause for ocean acidification. But it is more logical to link back to carbon sinks.
To go further
The surplus CO2 is permanently stored in the atmosphere (no chemical degradation process). There are only 2 physical processes: dissolution of CO2 in the oceans, and synthesis of CO2 via photosynthesis (in the presence of photons).
- in 100 years' time, 40% of the surplus CO2 released today will still remain in the atmosphere
- in 1000 years' time, 20% of the surplus CO2 emitted today will still remain in the atmosphere
- in 10,000 years' time, 10% of the surplus CO2 emitted today will still remain in the atmosphere.
It is an almost irreversible process.
French emission factors
In France, the main cause of CO2 emissions has shifted from industry to transportation in 150 years.