As the Senate considers the fate of the cap-and-trade bill, we should consider what it means for more carbon dioxide to be added to the atmosphere, something the bill intends to prevent.
Carbon dioxide is first and foremost a plant food. In fact, plants take carbon dioxide from the atmosphere and use the energy from sunlight to combine the CO2 with water to yield glucose, the simplest sugar molecule. Carbon dioxide is also the source of all organic — this word just means “contains carbon” — molecules synthesized by plants. Without carbon dioxide in the atmosphere, there would be no organic molecules synthesized by plants. The less carbon dioxide there is in the atmosphere, the fewer organic molecules synthesized by plants. All animals depend on plants to synthesize essential organic molecules. Without the organic molecules synthesized by plants, the animal world could not exist. Without plants, there would be no biosphere.
Several million years ago, a disaster struck the terrestrial biosphere: there was a drastic reduction in the percentage of CO2 in the atmosphere.
The flowering plants evolved to be most efficient when the percentage of CO2 in the atmosphere was about 1,000 parts per million. But the percentage had dropped to a mere 200 parts per million. Plants tried to adapt by evolving a new, more efficient way of using the little remaining CO2. The new mechanism, the C4 pathway, appeared in grasses, including corn and wheat, which enabled these plants to expand into the plains. If the carbon dioxide percentage had stayed low — or worse, had decreased further — the entire biosphere would have been endangered.
Fortunately for the plants and the rest of the biosphere depending on them, a wonderful thing happened about 150,000 years ago: a new animal species, Homo sapiens, evolved. This creature was endowed with a huge brain, enabling it to invent a way to help the plants with their CO2 problem. Gigantic amounts of carbon had been deposited deep underground in the form of coal, oil, and natural gas. Not only were these reservoirs of carbon locked away in rock, but they were in forms of carbon that the plants could not use.