Broadcast: July
4, 2003
This is the VOA Special English Environment Report.
Scientists in the United
States say plant life has increased on Earth in the past
twenty years. And they say in every area of plant growth the
increase is the result of weather conditions.
Eight scientists from across the United States did the
study. The space agency NASA and the Department of Energy paid
for it. The magazine Science published the findings.
The researchers spent a year-and-a-half examining weather
and satellite information. The information was recorded from
nineteen-eighty-two to nineteen-ninety-nine. This period was
one of the warmest on record. Researchers found that rainfall
generally increased during this time.
The satellites measured the
amount of leaves on plants and the amount of sunlight taken
in. The scientists used that information to estimate what is
called net primary production. This is the total amount of
carbon stored in land plants.
The scientists report a six percent increase in stored
carbon since nineteen-eighty-two. They say gains were high in
equatorial areas, especially around the Amazon River in South
America. The report says that area alone had a one percent
increase in net primary production.
Ramakrishna Nemani of the
University of Montana in Missoula led the study. He says
reduced cloud cover led to the growth in the Amazon area. He
says the lack of clouds permitted more sunlight to get
through. More sunlight meant increases in photosynthesis. That
is the process by which plants use energy from sunlight to
produce the chemicals they need to grow.
Northern Canada, the north-central United States and
northern Europe were second in increased plant growth.
Ramakrishna Nemani says a rise in temperatures helped plants
there.
All together, the report says twenty-five percent of areas
of plant life on Earth experienced increases. But, the
scientists also note increases in the number of people on
Earth and carbon dioxide levels in the atmosphere. Study
scientist Ranga Myneni of Boston University in Massachusetts
says humans use about half the net primary production on
Earth. And, he notes that world population grew by thirty-six
percent during the period of time studied.This VOA Special
English Environment Report was written by Caty Weaver.
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