Significant quantities of carbon dioxide and other greenhouse gases have been emitted into the atmosphere by human activities over the past century. In order to generate energy, most of the gases come from burning fossil fuels. Greenhouse gases around the World are like a blanket that traps energy in the atmosphere and allows it to burn. This is called the greenhouse effect and promoting life on earth is natural and necessary. When greenhouse gases accumulate, however, climate changes and leads to dangerous effects on human health and habitats. Since the last ice age, which ended several thousand years ago, people have adapted to the stable climate we have enjoyed.
Global warming is the unusually rapid increase in the Earth's average surface temperature over the past century. It is due to the increase in greenhouse gases released as people burn fossil fuels. Almost 30 percent of incoming sunlight is reflected back into space by bright surfaces like clouds and ice. When snow and ice melts Earth's climate warms, less energy is reflected, and this causes even more warming. Climate has cooled and warmed throughout the Earth history for various reasons, including volcanic eruptions and changes in solar energy. 2010 and 2005 has been the warmest years on record. Scientists have confidence that global temperatures will continue to rise for decades to come. The earth could warm by an additional 7.2 degrees Fahrenheit during the 21st century if we fail to reduce emissions. The rising of temperature will have great effects on the earth's climate patterns and on all living things.
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