www射-国产免费一级-欧美福利-亚洲成人福利-成人一区在线观看-亚州成人

English 中文網 漫畫網 愛新聞iNews 翻譯論壇
中國網站品牌欄目(頻道)
當前位置: Language Tips> Audio & Video> 新聞播報> Normal Speed News VOA常速

Dust from farming may affect rainfall

[ 2010-07-09 11:30]     字號 [] [] []  
免費訂閱30天China Daily雙語新聞手機報:移動用戶編輯短信CD至106580009009

Dust from farming may affect rainfall

Dust storm in the Sahara

Dust is more than a housekeeping nuisance. To climate scientists, dust is a force of nature. It's the most abundant particle in the atmosphere, and it reflects sunlight and heat.

The world's biggest source of dust is the Sahara desert and Sahel region of West Africa. The influence West African dust has on the environment is surprisingly wide-ranging, according to Stefan Mulitza, a marine geologist at the University of Bremen in Germany.

"It probably interacts with cloud formation; people think that it has an influence on the quantity of precipitation; hurricane activity through the cooling of the sea surface is probably affected; and last but not least, the quality of the air we breathe."

3,000 years of dust

But it's been hard for scientists to unravel what impact human activity has had on dust production in West Africa, in part because good data from satellites and ground stations has only been available for the last few decades.

Dust from farming may affect rainfall

Saharan dust blowing off Northwest Africa to the Atlantic Ocean

In a new study in the journal Nature, Mulitza and his colleagues studied ocean sediments off the coast of Senegal and Mauritania. They constructed a record of West African dust production stretching back more than 3,000 years.

For nearly that entire period, dust generation followed a predictable pattern: more dust in drier years, less in wetter ones. But then, beginning in the 19th century, something surprising happened: dust production increased dramatically.

Mulitza says that increase in dust coincides with a major economic change in the Sahel region.

"In the 19th century groundnuts were introduced into Senegal, just as one example," he says. "And there was a very widespread commercial agriculture to fuel the groundnut oil industry."

Unintended consequences

Farmers in the Sahel cleared forests to produce groundnuts and other cash crops. He says that disrupted the sandy soil and led to a sharp increase in the amount of dust blowing off the Sahel.

Dust from farming may affect rainfall

Mauritanian landscape. The photo was taken on a field trip to Mauritania led by Jan-Berend Stuut in November 2009.

And that dust may have been one factor behind the drier climate in the region over the past few centuries. Although the effects of dust on climate are complex and not fully understood, it may cool surface temperatures, which can shift precipitation patterns away from the region.

Atmospheric scientist Charlie Zender at the University of California at Irvine says this is the first study to link farming with increased dust generation in the world's largest source of dust. And he says there may be lessons for farmers elsewhere in the world.

"In those regions where rainfall isn't plentiful and abundant, this study suggests that using those surfaces for agriculture, using that land, will lead to these types of unintended consequences, whether that's in Africa or not," he says.

Cooling dust

Cornell University climate researcher Natalie Mahowald says if future studies confirm Mulitza's findings, it could have larger implications for climate change research.

"It would mean that there has been a cooling from dust over the 20th century that we haven't really been thinking about previously," she says. "And this cooling could be hiding some of the increase or the warming that should be happening from carbon dioxide."

Mahowald says that could mean the Earth is more sensitive to the warming effects of carbon dioxide than previously thought.

precipitation: rain, snow, etc. that falls; the amount of this that falls 降水,降水量(包括雨、雪、冰等)

groundnut: peanut 花生

Related stories:

UNEP to assess Expo carbon footprint

日政府呼吁民眾早睡早起 減少碳排放

七個潛伏在身邊的生態危害

Study warns of dangers to world's mangrove forests

(來源:VOA 編輯:陳丹妮)

 
中國日報網英語點津版權說明:凡注明來源為“中國日報網英語點津:XXX(署名)”的原創作品,除與中國日報網簽署英語點津內容授權協議的網站外,其他任何網站或單位未經允許不得非法盜鏈、轉載和使用,違者必究。如需使用,請與010-84883631聯系;凡本網注明“來源:XXX(非英語點津)”的作品,均轉載自其它媒體,目的在于傳播更多信息,其他媒體如需轉載,請與稿件來源方聯系,如產生任何問題與本網無關;本網所發布的歌曲、電影片段,版權歸原作者所有,僅供學習與研究,如果侵權,請提供版權證明,以便盡快刪除。
 

關注和訂閱

人氣排行

翻譯服務

中國日報網翻譯工作室

我們提供:媒體、文化、財經法律等專業領域的中英互譯服務
電話:010-84883468
郵件:translate@chinadaily.com.cn
 
 
主站蜘蛛池模板: 好爽~好硬~好紧~蜜芽 | 国产精品久久国产三级国电话系列 | 国产美女视频黄a视频全免费网站 | 中文国产成人精品久久无广告 | 久久久久视频精品网 | 亚洲性欧美 | 国产91精品久久久久久久 | 91精品91久久久久久 | 欧美高清videossex19 | 国内自产拍自a免费毛片 | 成人免费国产欧美日韩你懂的 | 欧美5g影院天天爽天天看 | 亚洲一区在线视频观看 | 成人夜色香网站在线观看 | 中国一级淫片aaa毛片毛片 | 国产一区二区三区高清视频 | 九色97| 成年人免费在线视频观看 | 国产在线精品一区二区 | 国产乱子伦视频大全 | 成人三级视频在线观看 | 国产亚洲精品久久 | 国产特黄一级一片免费 | 久9青青cao精品视频在线 | 国产三级在线视频播放线 | 久久成人精品免费播放 | 一级做a爰片久久毛片美女 一级做a爰片久久毛片免费看 | 欧美另类特大 | 成年人免费观看视频网站 | 国产综合久久久久影院 | 亚洲欧美韩国 | 九九精彩视频在线观看视频 | 玖玖这里只有精品 | 国产亚洲精品国产 | 国产精品欧美一区二区三区 | 成年人免费视频网站 | 国产精品永久免费视频观看 | 曰韩三级 | 欧美大狠狠大臿蕉香蕉大视频 | 亚洲精品一区二区三区国产 | 欧美午夜性春猛交 |