Increasing ozone levels due to the growing use of fossil fuels will damage global vegetation and result in serious costs to the world's economy, a new study in the November issue of Energy Policy has revealed.
The analysis focused on how three environmental changes (increases in temperature, carbon dioxide and ozone) associated with human activity affected crops, pastures and forests.
The research showed that increases in temperature and in carbon dioxide might actually benefit vegetation, especially in northern temperate regions.
However, those benefits might be more than offset by the detrimental effects of increases in ozone, notably on crops, the findings revealed.
Ozone, a form of oxygen, the researchers said, was an atmospheric pollutant at the ground level.
The scientists 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.
The researchers found that the economic cost of the damage could 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 would be considerable. If nothing were done, by 2100 the global value of crop production would fall by 10 to 12 percent, they said. "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," he said.
The study further said that without emission restrictions, growing fuel combustion worldwide would push global average ozone up 50 percent by 2100. That increase would have a disproportionately large impact on vegetation, as ozone concentrations in many locations would rise above the critical level where adverse effects are observed in plants and ecosystems.
"What is the net effect of the three environmental changes? Without emissions restrictions, yields from forests and pastures would decline slightly or even increase because of the climate and carbon dioxide effects. But crop yields would fall by nearly 40 percent worldwide," the study said.