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How does carbon dioxide affect the Earth's atmosphere?

As of October 2012, carbon dioxide in the atmosphere has reached 391 parts per million. The Northern Hemisphere has much greater land area and plant biomass as opposed to the Southern Hemisphere. The Northern Hemisphere dominates the annual cycle of carbon dioxide. Carbon dioxide annually fluctuates about 3-9 ppmv which follows the Northern Hemisphere's growing season.

The initial carbon dioxide in the Earth's atmosphere was produced by volcanic activity. Many sources of carbon dioxide are natural. They are generally balanced to various degrees by natural carbon dioxide sinks. Some natural sources of carbon dioxide include volcanic outgassing, combustion of organic matter, and wildfires. Plants convert carbon dioxide to carbohydrates through photosynthesis. Oxygen is then secreted into the atmosphere by plants.

Carbon dioxide is a greenhouse gas. It absorbs radiation from the thermal infared range. Because it is a greenhouse gas, carbon dioxide greatly affects the temperature of the earth. Without greenhouse gasses, the earth's temperature would be 30 degrees colder than the average temperature. The green house gases that impact the gradual warming of earth's surface are those that stay in the atmosphere for long periods of time. Carbon dioxide, has an atmospheric life of 50 to 200 years. Once Carbon dioxide is emitted into the atmosphere, its warming effect on the environment has a lasting impact.

The current level of greenhouse gases has increased significantly within the past couple decades. Carbon Dioxide in particular has fluctuated from 180 parts per million to about 330 parts per million. One of the major effects that green house gases has is raising the global temperature. The average global temperature will rise at least 2.2 degrees Fahrenheit by 2030 and there is no scientific evidence to show that the rising temperature will stop within the next 100 years.