Unit 4 Global warming 2014-12-15 陈文华
There is no doubt (1) ______ the earth is becoming
warmer but there is fierce debate over whether it is human activity that has caused thi
s global warming or whether it is just a natural phenomenon . Many scientists like Dr.Janice Foster believe that people have caused the increase in the earth’s temperature（2） burning of fossil fuels like coal, natural gas and oil to produce energy (3) ___ byproducts are called (4)
“greenhouse” gases, the most important one
carbon dioxide. These gases trap heat from the sun and therefore warm the earth, without which the earth (5) _________(be) about thirty-three degrees Celsius cooler than it is. But increased amount of carbon dioxide means that (6) ____heat energy is trapped in the atmosphere, (7)_______ (cause) the global temperature to go (8)____. On (9) ____ other hand, scientists like George
Hambley believe that any warming will be mild with (10)______ bad environmental consequences and more carbon dioxide is actually a positive thing.
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