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Ozone's Negative Impact on Grain Production in Asia: Can CO2 Help?
Wang, X. and Mauzerall, D.L.  2004.  Characterizing distributions of surface ozone and its impact on grain production in China, Japan and South Korea: 1990 and 2020.  Atmospheric Environment 38: 4383-4402.

The authors report that East Asia hosts 25% of the world's population but produces only 21% of the planet's total cereals.  Food security, therefore, has been a long-standing concern of the region, especially of China, which became a net importer of grain in 1999.  Also of concern, according to the authors, is the fact that East Asia is experiencing increasingly serious air pollution, particularly by ozone (O3), which negatively impacts agricultural productivity and thereby exacerbates the problem of diminishing food security.

What was done
"Using an integrated assessment approach," Wang and Mauzerall say they "evaluated the impact that surface O3 in East Asia had on agricultural production in 1990 and is projected to have in 2020."

What was learned
The authors' "conservative estimates," as they describe them, "show that due to O3 concentrations in 1990, China, Japan and south Korea lost 1-9% of their yield of wheat, rice and corn and 23-27% of their yield of soybeans," and that by 2020 "grain loss due to increased levels of O3 pollution is projected to increase to 2-16% for wheat, rice and corn and 28-35% for soybeans."  In addition, they say that "the associated economic costs are expected to increase by 82%, 33%, and 67% in 2020 over 1990 for China, Japan and South Korea, respectively."

What it means
Wang and Mauzerall conclude that "East Asian countries may have tremendous losses of crop yields in the near future due to projected increases in O3 concentrations."  We thus conclude they will need all the help they can get from (1) the aerial fertilization effect of the ongoing rise in the air's CO2 content, which increases the productivity of essentially all plants everywhere on earth (for numerous examples, see our Plant Growth Databases), together with (2) its anti-transpiration effect (see Stomatal Conductance (Agricultural Crops) and Transpiration in our Subject Index), which increases the water use efficiency of nearly all crops (see Water Use Efficiency (Agricultural Species) in our Subject Index), along with (3) its ability to often totally ameliorate the deleterious effects of O3 on plants (see Ozone (Effects on Plants - Agricultural Species) in our Subject Index), plus (4) its ability to significantly reduce isoprene emissions from plants, which leads to significant reductions in atmospheric O3 concentrations (see Isoprene in our Subject Index.

With rising atmospheric CO2 concentrations working these many different ways to thwart the negative impact of ozone on grain production in Asia, the region should be able to maintain its ability to meet its food needs in the years and decades ahead.  If mankind largely abandons the use of fossil fuels, however, or if expensive - or even inexpensive - techniques are developed to sequester carbon in the deep ocean or elsewhere, we will have to face the dire consequences of the hard reality that, to quote Wang and Mauzerall, "East Asian countries are presently on the cusp of substantial reductions in grain production."

Do we really want to do that?

Reviewed 23 February 2005