Carbon Journeys - Animate Earth: Science, Intuition and Gaia - page 106

Figure 25: The data from Mauna Loa.
High up on the Mauna Loa volcano, one finds air stirred together from all over the
northern hemisphere, with very little contamination from local sources. Scientists ana-
lysing this air found a regular oscillation, once again a bit like the 'breathing' we saw
in the Vostok ice core data ( Figure 5 ) , but this time with a yearly rhythm. What drives
this cycle? If you are a carbon dioxide molecule in the air somewhere in the high latit-
udes, it is possible that you'll be sucked up into a land plant through one of the minute
breathing pores, or stomata, on the underside of a leaf during the spring or summer when
there's plenty of moisture, light and warmth to fuel photosynthesis. Soon you become
part of a sugar molecule deep within the leaf. Then, in the autumn, your leaf is shed and
tumbles helter-skelter towards the ground. There a soil microbe absorbs the sugar mo-
lecule in which you find yourself. The tiny microbe uses oxygen to extract the energy in
the chemical bonds that bind you to your fellow carbon atoms, and you are once again
linked to two oxygen atoms and expelled into air through the microbe's semi-permeable