JOIN ME IN your imagination for a few minutes in the high Andes. The bamboo that arches over us here—like the tree that arches over your yard or nearby park—is at this very moment taking the carbon you and other creatures are breathing out. It then reforms this carbon into carbohydrate, powered by solar energy and hydrated with water (photosynthesis). It is making sugar from that CO2. The plant then uses this sugar to provide the energy and materials for making all sorts of new substances.
For example, if I take a leaf from a plant (such as lettuce or kale) and chew and swallow it, it is transformed within me to produce materials for sustaining my life, powering my walking and speaking and writing. And from its use I release carbon dioxide, returning through this gas the very same carbon the leaf had absorbed through the stomatal pores on its surface and incorporated into the leafy food I ingested. To complete the remarkable carbon cycle, the carbon I breathe out is eventually taken up again by green plants that in turn produce food for humans, bugs, birds, and batrachians! (Let’s hear a doxology!) Without green plants, all human life perishes—and most other animate life as well.
Plants accomplish a myriad of activities out of our sight. Beneath lawns and gardens, forests and prairies, roots are moving water from the soil, pulling it up through stems into the leaves and back into the atmosphere. All forests, all trees, all vegetation—great movers of water—are constantly returning to the atmosphere water that had fallen as rain. It rises again and again within the thin fabric of the biospheric envelope and condenses into those white clouds you see above to fall down again to water the earth.