Increased Ozone Levels Set To Cut Crops
A new 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 by MIT and the Marine Biological Laboratory published in the November issue of Energy Policy, (subscription required) focuses 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
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.
If nothing is done, by 2100 the global value of crop production will fall by 10 to 12%.
The analysis uses the MIT Integrated Global Systems Model, which combines linked economic, climate and agricultural computer models to project emissions of greenhouse gases and ozone precursors based on human activity and natural systems.
Results for the impacts of climate change and rising carbon dioxide concentrations (assuming business as usual, with no emissions restrictions) brought few surprises. For example, the estimated carbon dioxide and temperature increases would benefit vegetation in much of the world.
Without emissions restrictions, growing fuel combustion worldwide will push global average ozone up 50% by 2100. That increase will have a disproportionately large impact on vegetation because ozone concentrations in many locations will rise above the critical level where adverse effects are observed in plants and ecosystems.
Without emissions restrictions, yields from forests and pastures are projected to decline slightly or even increase because of the climate and carbon dioxide effects. But crop yields fall by nearly 40% worldwide.
However, those yield losses do not translate directly into economic losses. According to the economic model, the world adapts by allocating more land to crops. That adaptation, however, comes at a cost. The use of additional resources brings a global economic loss of 10-12% of the total value of crop production.
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