Global Warming
Global warming is an increase in the average temperature of Earth's surface. Since the late 1800's, the global average temperature has increased about 0.7 to 1.4 degrees F (0.4 to 0.8 degrees C). Many experts estimate that the average temperature will rise an additional 2.5 to 10.4 degrees F (1.4 to 5.8 degrees C) by 2100. That rate of increase would be much larger than most past rates of increase.
Scientists worry that human societies and natural ecosystems might not adapt to rapid climate changes. An ecosystem consists of the living organisms and physical environment in a particular area. Global warming could cause much harm, so countries throughout the world drafted an agreement called the Kyoto Protocol to help limit it.
Causes of global warming
Climatologists (scientists who study climate) have analyzed the global warming that has occurred since the late 1800's. A majority of climatologists have concluded that human activities are responsible for most of the warming. Human activities contribute to global warming by enhancing Earth's natural greenhouse effect. The greenhouse effect warms Earth's surface through a complex process involving sunlight, gases, and particles in the atmosphere. Gases that trap heat in the atmosphere are known as greenhouse gases.
The main human activities that contribute to global warming are the burning of fossil fuels (coal, oil, and natural gas) and the clearing of land. Most of the burning occurs in automobiles, in factories, and in electric power plants that provide energy for houses and office buildings. The burning of fossil fuels creates carbon dioxide, whose chemical formula is CO2. CO2 is a greenhouse gas that slows the escape of heat into space. Trees and other plants remove CO2 from the air during photosynthesis, the process they use to produce food. The clearing of land contributes to the buildup of CO2 by reducing the rate at which the gas is removed from the atmosphere or by the decomposition of dead vegetation.
A small number of scientists argue that the increase in greenhouse gases has not made a measurable difference in the temperature. They say that natural processes could have caused global warming. Those processes include increases in the energy emitted (given off) by the sun. But the vast majority of climatologists believe that increases in the sun's energy have contributed only slightly to recent warming.
The impact of global warming 
Thousands of icebergs float off the coast of the Antarctic Peninsula after 1,250 square miles (3,240 square kilometers) of the Larsen B ice shelf disintegrated in 2002. The area of the ice was larger than the state of Rhode Island or the nation of Luxembourg. Antarctic ice shelves have been shrinking since the early 1970's because of climate warming in the region. Image credit: NASA/Earth ObservatoryContinued global warming could have many damaging effects. It might harm plants and animals that live in the sea. It could also force animals and plants on land to move to new habitats. Weather patterns could change, causing flooding, drought, and an increase in damaging storms. Global warming could melt enough polar ice to raise the sea level. In certain parts of the world, human disease could spread, and crop yields could decline.
Global warming solutions
We have the technology and ingenuity to reduce the threat of global warming today. Solutions are already available that will stimulate the American economy by creating jobs, saving consumers money, and protecting our national security. By investing in renewable energy and energy efficiency, and increasing the efficiency of the cars we drive, we can take essential steps toward reducing our dependence on oil and other fossil fuels that cause global warming.
Using energy more efficiently and moving to renewable energy (wind, solar, geothermal, and bioenergy) would significantly reduce our emissions of heat-trapping gases. The United States currently produces 70 percent of its electricity from fossil fuels such as coal, natural gas, and oil, but only two percent from renewable sources. Since the burning of fossil fuels releases large amounts of carbon dioxide—the leading cause of global warming—but renewable energy does not, increasing the share of our electricity generated from renewable resources is one of the most effective ways to reduce global warming emissions.
Cars and trucks are another significant source (25 percent) of U.S. carbon dioxide emissions. A serious effort to address global warming must therefore reduce emissions from cars and trucks. Many technologies already exist that can do this, while also creating new jobs in the U.S. automotive sector and other industries throughout the country. In addition, American consumers would save billions of dollars on gasoline, and we would reduce our dependence on foreign oil.
By putting energy efficiency, renewable energy, and vehicle technology solutions in place at the federal level, we can reduce our contribution to global warming while creating a stronger, healthier, and more secure nation.
Here are two websites to read more about the Global Warming:
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