2. Greenhouse gases role Before the Industrial Revolution, the amount of carbon dioxide (CO2) and other greenhouse gases released into the atmosphere was in a rough balance with what could be stored on Earth. Natural emissions of heat-trapping gases matched what could be absorbed in natural sinks. For example, plants take in CO2 when they grow in spring and summer, and release it back to the atmosphere when they decay and die in fall and winter.
3. When we started global warming. Industry took off in the mid-1700s, and people started emitting large amounts of greenhouse gases. Fossil fuels were burned more and more to run our cars, trucks, factories, planes and power plants, adding to the natural supply of greenhouse gases. The gases—which can stay in the atmosphere for at least fifty years and up to centuries—are building up beyond the Earth's capacity to remove them and, in effect, creating an extra-thick heat blanket around the Earth.
4. What studies have shown Already, people have increased the amount of CO2, the chief global warming pollutant, in the atmosphere to 31 percent above pre-industrial levels. There is more CO2 in the atmosphere now than at any time in the last 650,000 years. Studies of the Earth’s climate history show that even small changes in CO2 levels generally have come with significant shifts in the global average temperature.
5. What will happen Here is what will happen. As the greenhouse effect causes atmospheric temperatures to rise the polar ice caps will melt. As the ice caps melt the sea levels will rise and this will cause flooding in coastal areas and islands. As the seas become warmer thermal expansion will occur and much more land will become flooded. The warmer air and sea temperatures will cause a dramatic shift in weather patterns turning many lush green belts into deserts. The warmer seas will also spawn huge hurricanes, tornadoes, and thunder storms unlike any we have ever seen during our life times.
6. How rapid Are the effects The rate of warming is increasing. The 20th century's last two decades were the hottest in 400 years and possibly the warmest for several millennia, according to a number of climate studies. And the United Nations' Intergovernmental Panel on Climate Change (IPCC) reports that 11 of the past 12 years are among the dozen warmest since 1850.
7. The toll it’s already taken. The Arctic is feeling the effects the most. Average temperatures in Alaska, western Canada, and eastern Russia have risen at twice the global average, according to the multinational Arctic Climate Impact Assessment report compiled between 2000 and 2004.
8. Humans are definitely at fault! 20 Percent of America's carbon dioxide emissions have increased from the burning of fossil fuels since 1990. Industrialization, deforestation, and pollution have greatly increased atmospheric concentrations of water vapor, carbon dioxide, methane, and nitrous oxide, all greenhouse gases that help trap heat near Earth's surface.
9. Humans are definitely at fault The present trend of warmer sea temperatures, which have risen by an average of half a degree Celsius (0.9F) over the past 40 years, can be explained only if greenhouse gas emissions are responsible, new research has revealed.
10. Humans are definitely at fault In its 2001 report, the Intergovernmental Panel on Climate Change stated, "There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities." Carbon dioxide from fossil fuel burning and land clearing has been accumulating in the atmosphere, where it acts like a blanket keeping Earth warm and heating up the surface, ocean, and atmosphere. As a result, current levels of carbon dioxide in the atmosphere are higher than at any time during the last 650,000 years
11. Humans are definitely at fault Recent increases in atmospheric concentrations of carbon dioxide, methane, and nitrous oxide are so divergent from global patterns over the past several thousand years that “there is no doubt that increase is dominated by human activity,” said Dr. Susan Solomon, an atmospheric chemist at the University of Colorado Boulder
12. Humans are to blame Measurements of the concentration of carbon dioxide since 1959 (316 ppm) have revealed an increase to 388 ppm in 2010, or at an average 1.41 ppmper year. The concentration of carbon dioxide has increased an average of about 1.8 ppm per year over the past two decades. The concentration of carbon dioxide increased 2.87 ppm in 1997-98, more than in any other year of record
13. Works cited Images: Marian Koshland Science Museum of the National Academy of Sciences National Geographic National Oceanic and Atmospheric Administration (NOAA) Union of Concerned Scientists
14. Works cited Information: Marian Koshland Science Museum of the National Academy of Sciences National Geographic New York Times Union of Concerned Scientists The United Nations National Oceanic and Atmospheric Administration (NOAA)
