December
4, 2006
REDUCING POLLUTION
COULD
INCREASE RICE HARVESTS IN INDIA,
STUDY SAYS
New
research from the University of California
indicates
that reductions of human-generated air pollution could create
unexpected agricultural
benefits in one of the world's poorest regions. These new findings will
be published
online the week of December 4 in the journal Proceedings of the National Academy of Sciences
(PNAS).
Rice
harvests increased dramatically in India
during the "Green
Revolution" of the 1960s and 1970s, making the country self-sufficient
in
its staple food. Harvest growth has slowed since the mid-1980s,
however,
raising concerns that food shortages could recur in this densely
populated and
poor nation. Several explanations for the slowdown have been proposed,
but
until now, none took into account the complex interactions of two
pollution-related sources of climate change: atmospheric brown clouds
(ABCs),
which form from soot and other fine particles in the air (collectively
termed
aerosols), and the better-known problem of global warming caused by
greenhouse
gases such as carbon dioxide.
In
the PNAS paper, Maximilian Auffhammer at UC Berkeley's College
of Natural Resources,
and V. "Ram" Ramanathan and
Jeffrey Vincent, researchers at UC San Diego, analyze historical data
on Indian
rice harvests and examine the combined effects of atmospheric brown
clouds and
greenhouse gases on growing conditions. They find that the combined
effects
were negative and were greater after the mid-1980s than before,
coinciding with
the observed slowdown in harvest growth. They estimate that harvests
would have
been 20 to 25 percent higher during some years in the 1990s if the
negative
climate impacts had not occurred.
Previous
research by an international scientific team led by Ramanathan,
professor of
atmospheric sciences at Scripps Institution of Oceanography, found that
brown
clouds have made the Indian subcontinent drier and cooler. Although
this
suggests the existence of a climatic tradeoff, with reductions in
aerosols
potentially unleashing a stronger warming trend, the current study
indicates
that joint reductions in the two types of pollutants would, in fact,
benefit
Indian rice farmers. This is because reductions in aerosols would
enhance
rainfall, while reductions in greenhouse gases would reduce the higher
nighttime temperatures that can negatively affect the growth of the
rice plant.
"Greenhouse
gases and aerosols in brown clouds are known to be competing factors in
global
warming," said Ramanathan. "The major finding of this
interdisciplinary study is that their effects on rice production are
additive,
which is clearly an unwelcome surprise."
Peter
Timmer, senior fellow at the Center for Global Development, an
independent, non-profit
think tank in Washington,
D.C.,
added that the study "links a sophisticated model of agricultural
production in India
to
climate and pollution models, with the critical finding that 'brown
cloud'
pollution has already cost India
millions of tons of food production."
The
researchers noted that the impact of ABCs and greenhouse gases on
agriculture
provides another incentive for controlling air pollution in heavily
polluted Asia.
"Air pollution control measures in India
have been
motivated mainly by concern about the health of residents of the urban
areas
where most of the pollution is generated," said Vincent, an economist
and
environmental research director at the UC Institute on Global Conflict
and
Cooperation (IGCC). "Our study provides an additional motivation
related
to the economic health of poor rural areas."
Auffhammer,
UC Berkeley assistant professor of agricultural and resource economics,
added
that "while this study focuses on India's
rain-fed states, ABCs exist throughout Asia's
main rice-producing countries, many of which have experienced
decreasing growth
rates in harvests, too. Furthering our understanding of how air
pollution
affects agricultural output is very important to ensure food security
in the
world's most populous region."
The
paper is the result of a three-year collaboration between Auffhammer,
Ramanathan and Vincent. Their work was supported in part by the
Giannini
Foundation, the National Science Foundation, the National Oceanic and
Atmospheric Administration and IGCC.
##
Contact:
Sarah
Yang
University
of California-Berkeley
510-643-7741
scyang@berkeley.edu
This
text derived from:
http://www.agu.org/sci_soc/prrl/prrl0642.html
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