En-en adult card 11 concentration of co2

Card #11: Concentration of CO₂

Causes		Consequences
Carbon Sinks		Additional Greenhouse Effect

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.

Explanation

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.

Correction

Causes

• Carbon Sinks

Consequences

• Additional Greenhouse Effect

Wrong links

Wrong consequences

• 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

CO₂ elimination

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).

Therefore:

• 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.