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  3. Soot(煤烟灰)and Snow: a Hot Combination New research from NASA scientists suggests emissions of black soot after the way sunlig

Soot(煤烟灰)and Snow: a Hot Combination New research from NASA scientists suggests emissions of black soot after the way sunlig

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问题                     Soot(煤烟灰)and Snow: a Hot Combination
    New research from NASA scientists suggests emissions of black soot after the way sunlight reflects off snow. According to a computer simulation, black soot may be responsible for 25 percent of observed global warming over the past century.
    Soot in the higher latitudes(维度)of the Earth, where ice is more common, absorbs more of the sun’s energy and warmth than an icy, white background. Dark-colored black carbon, or soot, absorbs sunlight, while lighter colored ice reflects sunlight.
    Soot in areas with snow and ice may play an important role in climate change. Also, if snow and ice covered areas begin melting, the warming effect increase, as the soot becomes more concentrated on the snow surface. "This provides a positive feedback, as glaciers and ice sheets melt, they tend to get even dirtier. " said Dr. James Hansen, a researcher at NASA’s Goddard Institute for Space Studies, New York.
    Hansen found soot’s effect on snow albedo(反照率), which may be contributing to trends toward early springs in the Northern Hemisphere, such as thinning Arctic sea ice and melting glaciers permafrost. Soot also is believed to play a role in changes in the atmosphere above the oceans and land.
    " Black carbon reduces the amount of energy reflected by snow back into space, thus heating the snow surface more than if there were no black carbon, " Hansen said. Soot’s increased absorption of solar energy is especially effective in warming the world’s climate. "This forcing is unusually effective, causing twice as much global warming as a carbon-dioxide forcing of the same magnitude. " Hansen noted.
    Hansen cautioned, although the role of soot in altering global climate is substantial, it does not alter the fact that greenhouse gases are the primary cause of climate warming during the past century. Such gases are expected to be the largest climate forcing for the rest of the century.
    The researchers found that observed warming in the Northern Hemisphere was large in the winter and spring at middle and high latitudes. These observations were coherent with the researchers’ climate model situations, which showed some of the largest warming effects occurred when there were heavy snow cover and sufficient sunlight.
The largest warming effects happened in the Northern Hemisphere with______.
选项 A、thin sea ice and insufficient sunlight
B、light snow cover and sufficient sunlight
C、heavy snow cover and sufficient sunlight
D、thick sea ice and sufficient sunlight
答案C
解析 由最后一段最后一句“…which showed some of the largest warming effects occurredwhen there were heavy snow cover and sufficient sunlight．”知，部分大规模的温室效应发生在有厚雪覆盖层和阳光强烈的地方。故本题选C。
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本试题收录于： 职称英语理工类C级题库职称英语分类
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