lizrising:

> Please explain how vegetation produces CO2. I must have missed that lesson in biology class.

Plants, just like animals, consume carbohydrate for energy and growth. A plant releases carbon dioxide as it uses carbohydrate as fuel. A plant releases and absorbs carbon dioxide and oxygen through stomata on the leaves. During the day the plant udergoes photosynthesis and converts carbon dioxide and water into carbohydrate and oxygen. This carbohydrate is used to provide energy as well as a raw material for growth. At night there is no sunlight so photosynthesis stops. Instead the plant uses the carbohydrate and releases carbon dioxide and water, the reverse of photosythesis. The plant grows because during the day it produces far more carbohydrate than it burns. Since the amount of carbohydrate is in excess of what is consumed for energy, the plant produces a much larger amount of oxygen than the amount of carbon dioxide. While a plant produces carbon dioxide, the net result is one of oxygenation of the atmosphere. Plants remove carbon dioxide and turn into glucose, which is in turn polymerized into cellulose. When you see a tree, the trunk, branches, leaves, etc. are a big store of carbon dioxide converted into cellulose. That cellulose can be burned for energy. It is why wood is a good fuel. But when we burn wood all that stored CO2 is realeased back into the atmosphere.

Does more CO2 mean more vegetation? In a greenhouse it does. Many greenhouses enrich the atmosphere with CO2 to stimulate plant growth. it works because the plants get warth, CO2, fertilizer and water. On the global scale of our atmosphere more CO2 does not translate into more vegetation when rainfall is low or the soil can't retain moisture. With global warming, rainfall will become erratic or change its patterns. The soil will retain less humidity. So more atmosphereic CO2 might mean death of vegetation rather than a lush jungle everywhere.