2. 外语
  3. Soot—also known as black carbon—heats up the atmosphere because it absorbs sunlight. But for years the institutions that focus o

Soot—also known as black carbon—heats up the atmosphere because it absorbs sunlight. But for years the institutions that focus o

admin2015-07-31  30
问题     Soot—also known as black carbon—heats up the atmosphere because it absorbs sunlight. But for years the institutions that focus on climate policy have played down the role of pollutants such as black carbon that stay in the atmosphere for a short time and concentrated on carbon dioxide, which, once generated, tends to remain there. That may soon change.
    A new study concluded that the soot was the second-most-damaging greenhouse agent after CO2 and about twice as bad for the climate as had been thought until now. The implications are profound. It found that the black carbon around at the moment has a warming effect of about 1.1 w/m2. This is greater than that of methane(甲烷)and second only to the 1. 7 w/m2 of carbon dioxide.
    Black carbon is especially damaging to frozen regions, because when soot falls on snow and ice it increases the amount of light and heat they absorb. The new assessment may therefore help explain why the Arctic has been melting faster than anyone had expected. The study argues that warming is likely to be especially marked in the high latitudes of the northern hemisphere— northern Canada, Alaska, northern Europe and Siberia. It also gives a warning that black carbon, by changing regional precipitation(降水)patterns, may affect Asian monsoons(季风).
    The biggest impact of soot, though, is not on the climate but on health—through lung and other diseases. A study reckoned that controlling emissions of black carbon could save 2.4 million lives a year, regardless of any effects on the climate.
    It might seem that the new study is one more item of bad environmental news. Not so. It should be easier to deal with black carbon than with CO2. Whereas CO2 is long-lasting and an inevitable by-product of burning fossil fuels, soot drops out of the atmosphere within weeks. Stop putting it there and it will rapidly go away—a potentially easy win. Dealing with them is also cheaper than cutting CO2 emissions and does not need global agreement, because the local benefits would be the main point, so no one could free-ride on the emission-cutting efforts of others. Instead, the good of the climate would be free-riding on local self-interest.  
What does the word "free-ride" really mean in the last paragraph?
选项 A、Getting to certain place without paying the fee.
B、Gaining benefits without doing any efforts.
C、Giving somebody a free ride.
D、Driving a car in one’s own power.
答案B
解析 推理判断题。要结合上下文在具体的语境中理解词义。文章提到，此外，处置煤烟比减少二氧化碳排放成本更低，并且不需要全球协定。因为地方会从中最大受益，所以没有人可以搭乘别人减排努力的便车。可知这里free-ride的真正含义是“不劳而获”，故选B)。
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