Despite the harmful effects generally associated with
it, the greenhouse effect may actually bring surprising
benefits by helping the spread of forests and halting
global warming says a team of researchers headed by
Professor Dan Yakir of the Department of Environmental
Science and Energy Research at the Weitzman Institute.
The greenhouse effect refers to the accumulation of
carbon in the atmosphere, apparently due to the
increased combustion of carbon-based fuels such as coal
and petroleum, and the warming effects this increase
has.
The new discovery, based on a study of the absorption
of gases in the Yatir Forest in the Negev Desert,
offers a solution to a mystery that has occupied
scientists for years. The emission of carbon dioxide by
industrial manufacturers is a widespread phenomenon
well known for the damage it causes-- the increase in
the amount of gases emitted into the atmosphere is held
to be largely responsible for global warming and the
resulting climate changes. Every year, 22 billion tons
of carbon dioxide are released into the atmosphere by
industrial manufacturers. Yet when scientists measure
the increase in atmospheric carbon dioxide levels, half
of this amount somehow vanishes. Even after
compensating for the amount absorbed into the oceans,
some 7 billion tons remain unaccounted for.
In the study performed at Yatir Forest which was
planted 35 years ago on the edge of the Negev, the
research team determined that forests spreading into
desert areas may be absorbing a portion of the
"disappeared" carbon dioxide. Until now it was commonly
believed that forests in arid areas do not absorb much
carbon dioxide since they form relatively slowly and
the amount of plant growth in them is limited.
Professor Yakir discovered that the ability of a forest
bordering a desert to absorb carbon dioxide is no less
than that of forests in other locations, including
those located in lush, fertile areas.
Professor Yakir's hypothesis for the forest's success
is based on the water-conservation mechanism employed
by plants and trees, which needs carbon dioxide to
execute the photosynthesis process that leads to the
manufacture of simple carbohydrates.
In order to absorb the carbon dioxide, they must open
the pores in their leaves, which means risking water
loss through evaporation. The solution to this dilemma
is the high level of carbon dioxide in the atmosphere,
which allows plants to use relatively smaller openings
in order to absorb the carbon dioxide they need without
losing excess water. This effective water-saving
technique keeps moisture in the ground and allows the
forest to grow more efficiently and even to expand into
areas once too dry to support forest growth. The
conclusion: apparently the additional carbon dioxide in
the atmosphere also carries certain benefits, since in
effect it makes more water available to plants and
trees in dry climate areas.
On a global level such a phenomenon may be manifested
in a significant increase in forested areas, which
increases the absorption of carbon dioxide from the
atmosphere and works to slow the global warming
process. These findings could help develop efficient
ways of halting desertification and fostering
forestation and agriculture in arid areas.
