Greenhouse gases, especially carbon dioxide, trap the heat of the sun and have helped cause a global temperature increase of 1 degree in the past century. The United States is the world's largest contributor to the greenhouse effect, which has been linked to extreme weather.
| United States | 21% |
| Commonwealth of Independent States (former USSR) | 14% |
| European Economic Community | 14% |
| China | 7% |
| India | 4% |
| Brazil | 4% |
| Rest of the World | 36% |
Source: environmental protection agency
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