Global Warming

Global warming is the increase in the average temperature of the atmosphere, oceans, and landmasses of Earth. The planet has warmed (and cooled) many times during the 4.65 billion years of its history. At present Earth appears to be facing a rapid warming, which most scientists believe results, at least in part, from human activities. The chief cause of this warming is thought to be the burning of fossil fuels, such as coal, oil, and natural gas, which releases into the atmosphere carbon dioxide and other substances known as greenhouse gases. As the atmosphere becomes richer in these gases, it become a better insulator, retaining more of the heat provided to the planet by the Sun.

The average surface temperature of Earth is about 15*C(59*F). Over the last century, this average has risen by about 0.6 Celsius degree (1 Fahrenheit degree). Scientists predict further warming of 1.4 to 5.8 Celsius degrees (2.5 to 10.4 Fahrenheit degrees) by the year 2100. This temperature rise is excepted to melt polar ice caps and glacier as well as warm the oceans, all of which will expand ocean volume and raise sea level by an estimated 9 to 100 cm (4 to 40 in), flooding some coastal regions in warmer climates will receive more rainfall than before, but soils will dry out faster between storms. This soil designation may damage food crops, disrupting food supplies in some parts of the world. Plants and animals species will shift their ranges towards the poles or to higher elevations seeking cooler temperatures, and species that cannot do so may become extinct.