Just as the world’s most respected scientific bodies have confirmed that the wor

Just as theworld’s most respected scientific bodies have confirmed that the world isgetting hotter, they have also stated that there is strong evidence that humansare driving the warming. Countless recent reports from the world’s leadingscientific bodies have said the same thing. For example, a 2010 summary ofclimate science by the Royal Society stated that: “There is strong evidencethat the warming of the Earth over the last half-century has been causedlargely by human activity.”

The idea thathumans could change the planet’s climate may be counter-intuitive(与直觉不符的), but the basic science is wellunderstood. Each year, human activity causes billions of tons of greenhousegases to be released（释放）into the atmosphere. Asscientists have known for years, these gases hold heat that would otherwiseescape to space, wrapping the planet in an invisible blanket.

Of course, theplanet’s climate has always been changing thanks to “natural” factors(因素) such as changes in solar or volcanic（火山的）activity, or cycles relating the Earth’s going around the sun.According to the scientific literature, however, the warming recorded to datematches the pattern of warming we would expect from a build-up of greenhousegas in the atmosphere – not the warming we would expect from other possiblecauses.

Even ifscientists did discover another reasonable explanation for the warming observedso far, that would beg a difficult question. As Robert Henson puts it in TheRough Guide to Climate Change: “If some newly discovered factor can accountfor the climate change, then why aren’t carbon dioxide（二氧化碳）and the other greenhouse gasesproducing the warming that basic physics tells us they should be?”

The only way toprove with 100% certainty that humans are responsible for global warming wouldbe to run an experiment with two identical Earths – one with humaninfluence and one without. That obviously isn’t possible, and so mostscientists are careful not to state human influence as an absolute certainty.

1. In most scientists’ opinion, the global warming is mainlycaused by ________.

   A.solar activity                       

B. volcanicactivity

C. the Earth’sgoing around the sun    

D. human activity

2.The text is developed by ________.

   A.giving typical examples

   B.following the order of space

   C.analyzing a theory and arguing it

   D.comparing and finding differences

3.The underline word “identical” means ________.

   A.totally different                    

B. exactly thesame

   C.extremely important                  

D. relativelyindependent

4. Which of the following can be the best title?

   A.Are All the Scientists Really Scientific?

   B.Where Is Global Warming Leading Us to?

   C. Are Humans Definitely Causing Global Warming?

   D. What’s Relation of Global Warming andGreenhouse Gases?

试题答案

【答案】

1.D2.C3.B4.C

【解析】略