MIT: Human-Generated Ozone Will Damage Crops

CAMBRIDGE, Mass.--An MIT study concludes that increasing levels of ozone due to the growing use of fossil fuels will damage global vegetation, resulting in serious costs to the world's economy.

The analysis, reported in the November issue of Energy Policy, focused on how three environmental changes (increases in temperature, carbon dioxide and ozone) associated with human activity will affect crops, pastures, and forests.

The research shows that increases in temperature and in carbon dioxide may actually benefit vegetation, especially in northern temperate regions. However, those benefits may be more than offset by the detrimental effects of increases in ozone, notably on crops. Ozone is a form of oxygen that is an atmospheric pollutant at ground level.

The economic cost of the damage will be moderated by changes in land use and by agricultural trade, with some regions more able to adapt than others. But the overall economic consequences will be considerable. According to the analysis, if nothing is done, by 2100 the global value of crop production will fall by 10 to 12 percent.

"Even assuming that best-practice technology for controlling ozone is adopted worldwide, we see rapidly rising ozone concentrations in the coming decades," said John M. Reilly, associate director of the MIT Joint Program on the Science and Policy of Global Change. That result is both surprising and worrisome.

The MIT study is novel. While others have looked at how changes in climate and in carbon dioxide concentrations may affect vegetation, Reilly and colleagues added to that mix changes in tropospheric ozone. Moreover, they looked at the combined impact of all three environmental "stressors" at once. (Changes in ecosystems and human health and other impacts of potential concern are outside the scope of this study.)

They performed their analysis using the MIT Integrated Global Systems Model, which combines linked state-of-the-art economic, climate, and agricultural computer models to project emissions of greenhouse gases and ozone precursors based on human activity and natural systems.

MIT News Service, Oct. 30, 2007