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Scientists believe the Sahara desert is twice as old as we previously thought. Science books generally say the Sahara is around three million years old. However, a new study from a centre for climate research in Norway says it could be around seven million years old. Researchers used computers to try and calculate when large parts of North Africa became desert. Their tests showed that global warming seven million years ago dried a lot of the land in what is today the African nation of Chad. A sea called the Tethys Sea started shrinking. This made the African summer monsoons less frequent, which helped form sand dunes in Chad. The scientists say this is how the Sahara first started.
科学家认为撒哈拉沙漠比以前认为的存在时间要长两倍。科学书籍一般都写着撒哈拉沙漠存在的时间约为300万年。然而，挪威一所气候研究中心的一项新的研究表明，撒哈拉沙漠存在的时间可能是700万年。研究人员用电脑试着计算北非变成沙漠的时间。他们的实验表明，700万年以前的全球变暖造成许多土地变干，形成了现在的乍得国。特提斯海开始缩小。这使得非洲的夏季风频率变小。从而形成了乍得国的沙丘。科学家称，这就是撒哈拉沙漠最开始形成的状况。
The Sahara is one of the world's best-known and largest deserts. It covers about 10 per cent of the whole African continent and forms large parts of Algeria, Chad, Egypt, Sudan and other nations. The sands stretch from the Atlantic Ocean in the west to the Red Sea in the east. Not everyone agrees that the Sahara is as old as the Norway research says it is. Stefan Kröpelin, a geologist in Germany, says real geological evidence is needed to be sure. He said the Norway research is based on numbers and not evidence, saying: "Nothing you can find in the Sahara is older than 500,000 years old". He added that our knowledge of the Saharan climate is only from 10,000 years ago and that our knowledge is "full of gaps".
撒哈拉沙漠是世界上一片著名的最大的沙漠之一。撒哈拉沙漠面积约为非洲大陆的10%。而且覆盖了阿尔及利亚，乍得，埃及，苏丹和其他国家的大部分地区。沙漠从大西洋西部一直延伸至红海的东部。并不是所有人都认同挪威研究中心对撒哈拉沙漠存在时间的研究结果。德国地理学家斯特芬说，真正的地理证据需要核实。他说，挪威的研究并不是依据证据，而是依据数字。他说，在撒哈拉沙漠找到的任何东西的存在时间都小于50万年。他还说，我们所知道的关于撒哈拉沙漠地区的气候知识是在1万年以前，并且我们的知识有许多漏洞。
译文属可可英语原创，未经允许，不得转载。
