Benefits of Urban Trees Trees Fight the Atmospheric Greenhouse Effect Trees fight the atmospheric greenhouse effect. The greenhouse effect is created when heat from the sun enters the atmosphere and is prevented from radiating back into space by air-polluting gasses. The buildup of about 40 heat-trapping gasses is created mostly by human activities. Heat buildup threatens to raise global temperatures to levels unprecedented in human history. About half of the greenhouse effect is caused by carbon dioxide. Trees act as a carbon sink by removing the carbon from carbon dioxide and storing it as cellulose in the trunk while releasing the oxygen back into the air. A healthy tree stores about 13 pounds of carbon annually-or 2.6 tons per acre per year. Trees also reduce the greenhouse effect by shading our homes and office buildings. This reduces air conditioning needs up to 30 percent, thereby reducing the amount of fossil fuel burned to produce electricity. This combination to carbon dioxide removal from the atmosphere, carbon storage in wood, and the cooling effect makes trees a very efficient tool in fighting the greenhouse effect. « Return to the main page for the Benefits of Urban Trees.