GHG concentrations in the troposphere

The anthropogenic emissions of different gases increase their concentrations in the troposphere and enhance the greenhouse effects. Here we will discuss the relationship between sources (see Section 2) and sinks of the main GHG. 

Cyclic processes of carbon mass exchange are of particular importance for the global biosphere both in terrestrial and oceanic ecosystems. 

The residence time of CO2 in the atmosphere is about two years, which makes the atmospheric air quite well mixed with respect to this gas. However, a more recent analysis shows that the terrestrial ecosystems have much stronger sinks of carbon dioxide uptake. The details of major ecosystem-level CO2 experiments have been shown recently (Koch and Mooney, 1996). 

In the global ocean, along with the occurrence in living organisms, carbon is present in two major forms as a constituent of organic matter (in solution and partly in suspension) and as a constituent of exchangeable inorganic ions HCOJ, CO , and CO2 

One can see the peak about April and the drop through around October each year. These data indicate that the content of carbon dioxide in the Earth s atmosphere is not perfectly homogeneous. Some explanations would be of interest for understanding this figure. 

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