Global warming

Transcription

For 2.5 million years the Earth climate has fluctuated cycling from ice ages to warmer periods. But in the last century the planet's temperature has risen unusually fas about 1.2 to 1.4 degrees Fahrenheit. Scientists believe its human activity that's driving the temperatures up a process known as global warming. Ever since the industrial revolution began, factories, power plants and eventually cars have burned fossil fuels such as oil and pole releasing huge amounts of carbon dioxide and another gases into the atmosphere. These greenhouse gases trap heat near the earth through a naturally occurring process called the greenhouse effect. The greenhouse effect begins with the Sun and the energy it radiates to the earth. The earth and the atmosphere absorbs some of this energy while the rest is radiated back into space.

Naturally-occurring gases in the atmosphere trap some of this energy and reflected back warming the earth. Scientist now believe that the greenhouse effect is being intensified by the extra greenhouse gases that humans have released. Evidence for global warming includes a recent string of very warm years. Scientists report that 1998 was the warmest year in measured history with 2005 coming in second. Meanwhile readings taken from ice cores show that the greenhouse gases carbon dioxide and methane have hit  the highest levels in the past 420 thousand years.

Arctic sea ice is also shrinking. According to NASA studies the extent of Arctic sea ice has declined about ten percent in the last 30 years. As long as industrialized nations consume energy and developing countries increase their fossil fuel consumption the concentration of greenhouse gases in the atmosphere will continue to rise. Researchers predict that temperatures will increase about two to ten degrees Fahrenheit by the end of the century. What's less certain is what rising temperatures mean for the planet. Some climate models predict subtle charges, others forecast rising sea levels which could flood coastal areas around the world. Weather patterns could change, making hurricanes more frequent. Severe droughts could become more common in warm areas, and species unable to adapt to the changing conditions would face extinction.

Although much remains to be learned about global warming, many organizations advocate cutting greenhouse gas emissions to reduce the impact of global warming. Consumers can help by saving energy around the house, switching to compact fluorescent light bulbs and driving fewer miles in the car each week. These simple changes may help keep the earth cooler in the future. 

TRUE or FALSE?

1. In the last two centuries the earth's temperature has gone up really fast. F
2. Human actiity is believed to be responible for driving temperatures up. T
3. Factories, cars and smoking release huge amounts of carbon dioxide into the atmosphere. F
4. The greenhouse effect makes the earth warmer because some energy is radiated back into space. F 
5. Extra greenhouse gases produced by humans are believed to have intensified the greenhouse effect. T
6. 2005 has been reported to have been warmen than 1998. F
7. The extent of Arctic sea ice has shrunk about 10% in the last 13 years according to NASA studies. F
8. The less energy we consume, the more greenhouse gases sill concentrate in the atmosfere. F
9. The effect  of warmer temperatures in our planet is certain. F
10. Animal species will certainly adapt to the new conditions. F