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Atmospheric concentration of CO2
First published: 7 October 2016
The atmospheric concentration of CO2 has been steadily climbing since mankind began its long-term climate experiment of liberating long-buried fossil carbon. Before we began, concentration was below 300 ppm, but since then we have sent more than 2 trillion tonnes of CO2 into the atmosphere. While some of that has been absorbed by land and ocean 'sinks', much of it remains in the atmosphere, and will stay there for many hundreds of years.
Almost all the variation from week to week is natural, probably a result of shifting wind patterns bringing different air parcels to the sampling site, such that it is highly unlikely that we can discern anthropogenic effects from week to week. The steady increase from year to year, however, is clearly driven by our global emissions.
The seasonal cycle is dominated by northern hemisphere forests, following the pattern of plants' photosynthesis, which stores CO2, and microbial decay, which releases it again (more info). There is about twice as much land area in the northern hemisphere as in the southern hemisphere.
More text coming... In the meantime, check out the earlier (no longer updated) page here.
