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  3. Year after year, the world’s nations gather to find ways to reduce carbon dioxide, the main greenhouse gas, with little meaningf

Year after year, the world’s nations gather to find ways to reduce carbon dioxide, the main greenhouse gas, with little meaningf

admin2012-07-05  40
问题     Year after year, the world’s nations gather to find ways to reduce carbon dioxide, the main greenhouse gas, with little meaningful progress. Frustrated by this slow pace, the United States and five other countries announced this week a modest but potentially game-changing initiative to cut three other pollutants that also contribute significantly to climate change.
    The three pollutants—methane (甲烷), black carbon and hydrofluorocarbons (氢氟碳)—together account for about 30 percent to 40 percent of the rise in global temperatures. Unlike carbon dioxide, they do not remain in the atmosphere for a long time, but, while they are there, they drive temperatures upward.
    Mainstream scientists believe that to avoid disastrous increases in the sea levels and widespread drought, the rise in global temperatures by 2050 should not exceed 2 degrees Celsius above preindustrial levels. Though cuts in carbon dioxide will also be necessary to reach that goal, curbing these three pollutants will help enormously.
    Officials hope further that by tackling these pollutants they can achieve relatively quick and measurable reductions in emissions without waiting for politicians to act or the United Nations process to produce a global agreement on carbon dioxide.
    The plan’s founding members are the United States, Canada, Sweden, Mexico, Ghana and Bangladesh. Washington and Ottawa will jointly underwrite a $15 million start-up fund. Clearly, the program must be scaled up over time, with many more countries participating. In the short term, officials say their purpose is to educate and test inexpensive and technologically accessible ways of capturing these gases.
    Soot, a huge health hazard, can be reduced by installing filters on diesel engines, replacing traditional cook stoves with more efficient models and banning the open burning of agricultural waste. Methane can be captured from oil and gas wells, leaky pipelines, municipal (城市的) landfills and wastewater treatment plants.
    Significantly reducing hydrofluorocarbons, or HFCs, could be harder. These compounds, widely used in air-conditioners and originally developed to replace the refrigerants that were damaging the ozone layer, turned out to be a disastrous greenhouse gas. Efforts to find less-harmful substitutes have met resistance from countries like India, where most HFCs are manufactured.
    Governments everywhere should obviously be pushing to reduce carbon dioxide, the most dangerous greenhouse gas. In the meantime, opening an important second front in the climate war will demonstrate that progress is possible.  
Unlike carbon dioxide, the three pollutants______.
选项 A、don’t belong to greenhouse gas
B、don’t stay in the atmosphere for long
C、don’t drive temperatures up greatly
D、don’t belong to natural gases
答案B
解析
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