- 英语听力
- 加入收藏
- 听力课堂 www.TingClass.com 最大的在线英语听力网站，为了下次能再来学习，请牢记本站 www.TingClass.com 的网址
Caty Weaver
This is the VOA Special English Environment Report.
 |
| Graphic Image |
Scientists in the United Statessay plant life has increased on Earth in the past twenty years. Andthey say in every area of plant growth the increase is the result ofweather conditions.
Eight scientists from across the United States did the study. Thespace agency NASA and the Department of Energy paid for it. Themagazine Science published the findings.
The researchers spent a year-and-a-half examining weather andsatellite information. The information was recorded fromnineteen-eighty-two to nineteen-ninety-nine. This period was one ofthe warmest on record. Researchers found that rainfall generallyincreased during this time.
 |
| Graphic Image |
The satellites measured the amountof leaves on plants and the amount of sunlight taken in. Thescientists used that information to estimate what is called netprimary production. This is the total amount of carbon stored inland plants.
The scientists report a six percent increase in stored carbonsince nineteen-eighty-two. They say gains were high in equatorialareas, especially around the Amazon River in South America. Thereport says that area alone had a one percent increase in netprimary production.
 |
| Graphic Image |
Ramakrishna Nemani of theUniversity of Montana in Missoula led the study. He says reducedcloud cover led to the growth in the Amazon area. He says the lackof clouds permitted more sunlight to get through. More sunlightmeant increases in photosynthesis. That is the process by whichplants use energy from sunlight to produce the chemicals they needto grow.
Northern Canada, the north-central United States and northernEurope were second in increased plant growth. Ramakrishna Nemanisays a rise in temperatures helped plants there.
All together, the report says twenty-five percent of areas ofplant life on Earth experienced increases. But, the scientists alsonote increases in the number of people on Earth and carbon dioxidelevels in the atmosphere. Study scientist Ranga Myneni of BostonUniversity in Massachusetts says humans use about half the netprimary production on Earth. And, he notes that world populationgrew by thirty-six percent during the period of time studied.ThisVOA Special English Environment Report was written by Caty Weaver.