Originally posted by the Voice of America.
Voice of America content is produced by the Voice of America,
a United States federal government-sponsored entity, and is in
the public domain.


                Arid Areas Greening Because of Higher CO2 Levels

   by VOA News

   Higher levels of carbon-dioxide has caused some of the Earth's most
   arid regions to become more green, according to new research.
   Scientists focused on the American southwest, Australia's outback, the
   Middle East and parts of Africa, and found that from 1982 to 2010 there
   was a "fertilization effect" caused by increased carbon-dioxide levels.
   Researchers predicted foliage would increase by 5 to 10 percent given
   the 14 percent increase in atmospheric CO2 concentration during the
   study period. The satellite data agreed, showing an 11 percent increase
   in foliage after adjusting the data for precipitation variations,
   according to a study published by the [1]American Geophysical Union.
   The use of satellite imagery was key to the findings.
   "Satellites are very good at detecting changes in total leaf cover, and
   it is in warm, dry environments that the CO2 effect is expected to most
   influence leaf cover," said  Randall Donohue of the Commonwealth
   Scientific and Industrial Research Organization (CSIRO) in Canberra,
   Australia, who led the effort.
   Donohue added that leaf cover is a clue because "a leaf can extract
   more carbon from the air during photosynthesis, or lose less water to
   the air during photosynthesis, or both, due to elevated CO2."
   "If elevated CO2 causes the water use of individual leaves to drop,
   plants will respond by increasing their total numbers of leaves, and
   this should be measurable from satellite," he said.
   The scientists say they were able to isolate the effects of CO2 from
   other factors like precipitation, air temperature, the amount of light
   and land-use changes.
   This was done by first averaging out the greenness levels of each
   location over 3-year periods to account for changes in soil wetness,
   for example. They then predicted the maximum amount of foliage that
   could be attained with the given precipitation along with other
   climatic variations to see the long-term greening effect of CO2.
   The research also said that the fertilization effect could lead to
   different types of vegetation dominating the dry regions.
   "Trees are re-invading grass lands, and this could quite possibly be
   related to the CO2 effect," Donohue said. "Long lived woody plants are
   deep rooted and are likely to benefit more than grasses from an
   increase in CO2."
   While the researchers say the effects of fertilization as a result of
   higher CO2 levels need more study, it will likely lead to "significant
   environmental changes," even if nothing else in the climate changes
   said Donohue.
     __________________________________________________________________

   [2]http://www.voanews.com/content/arid-regions-greening-as-a-result-of-
   higher-co2-levels/1672998.html

References

   1. http://www.agu.org/news/press/pr_archives/2013/2013-24.shtml
   2. http://www.voanews.com/content/arid-regions-greening-as-a-result-of-higher-co2-levels/1672998.html