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  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  40
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.  
Why did the institutions pay less attention to soot?
选项 A、It is too small in amount in the atmosphere to be noticed.
B、It just stays in the atmosphere for a short time.
C、It belongs to carbon dioxide.
D、It is beyond their study.
答案B
解析 细节辨认题。由定位句可知，但是，关注气候政策的机构多年来忽视了只是短时间停留在大气中的污染物，如煤烟，却关注在空气中一旦集结就保持在那里的二氧化碳。因为煤烟停留时间短，所以未多关注，正确答案为B)。
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