This graph shows how the amount of carbon dioxide, a greenhouse gas in the Earth’s atmosphere, has changed over time and how it is expected to change in the future.
Click on image for full size
IPCC 2001 Third Assessment Report
The Changing Atmosphere Affects Earth's Climate
The molecules in Earth's atmosphere are always moving in and out of the air and changing through reactions. Even through the individual molecules are changing, the amounts of different elements within the atmosphere stays amazingly steady.
Even though the amount of most gases in the atmosphere is quite steady, scientists have found that the amount of greenhouse gases in Earth’s atmosphere has increased over the last 150 years. The rise in amount of greenhouse gases is directly related to human activities such as the burning of fossil fuels, deforestation, and curing of concrete. These activities are affecting Earth’s cycles such as the carbon cycle, the nitrogen cycle and the water cycle, influencing the planet as a whole.
Greenhouse gases trap heat through the greenhouse effect. There were greenhouse gases in the atmosphere long before humans affected the system. Having some greenhouse gases in Earth’s atmosphere is beneficial because they keep temperatures mild and suitable for life. However, as the amount of greenhouse gases has risen, so has Earth’s global temperature. This is causing changes to environments and ecologies around the world.
Last modified August 13, 2004 by Lisa Gardiner.
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