5. Why is Carbon Dioxide increasing?

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Just as the hydrological cycle describes the continual movement of water between the atmosphere, the land and the oceans, the carbon cycle refers to the transfer of carbon between these parts of the system. The best known of these exchanges is that which occurs between plants and the atmosphere through the process of photosynthesis. In this activity the plant extracts carbon from the atmosphere. However most carbon in the EAS is held in storage (that is, it does not participate in these exchanges).

Of all the carbon on earth the vast majority is held in the oceans, either in living organisms or in the bottom sediments. The next largest reservoir is held in the form of fossil fuels - coal, oil or gas. These materials represent carbon that has accumulated over millions of years as carbon life forms (primarily vegetation) died.

There is comparatively little carbon in the atmosphere and most of it is in the form of carbon dioxide. Over the last 250 years (since the industrial revolution began) these fossil fuels have been extracted and burned, releasing carbon dioxide in the process. Of all the carbon emitted by these activities about half is estimated to be still in the atmosphere and the remainder in the oceans.