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Study: Human-Generated Ozone Could Cut Global Crop Yields by Nearly 40% by 2100

Ozone
Projections of average percentage change in crop yield and production. In the top curve, CO2 and other GHGs are unregulated, excluding ozone impact. In the lowest curve, GHGs are unregulated, and crop damage from ozone is included. In the middle curve, GHGs are regulated, and ozone damage is included. The lower figure shows changes in total crop production under the same three scenarios. While crop yields drop significantly, total output never declines by more than 8% because the world adapts by allocating more resources to growing food. Click to enlarge. Courtesy John Reilly / MIT

An MIT study concludes that increasing levels of tropospheric ozone due to the increasing use of fossil fuels under a business-as-usual scenario could cut global crop yields by nearly 40% worldwide by 2100, forcing a greater global allocation of land to agriculture.

Published in the journal Energy Policy, the study focuses on the affect of three environmental changes (increases in temperature, carbon dioxide and ozone) associated with human activity. The research shows that while increases in temperature and in carbon dioxide may actually benefit vegetation on a global basis, especially in northern temperate regions, those benefits may be more than offset by the detrimental effects of increases in tropospheric 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, with a global economic loss of 10-12% of the total value of crop production.

Even assuming that best-practice technology for controlling ozone is adopted worldwide, we see rapidly rising ozone concentrations in the coming decades. That result is both surprising and worrisome.

—John M. Reilly, associate director of the MIT Joint Program on the Science and Policy of Global Change

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 ozone. Moreover, they looked at the combined impact of all three environmental stressors at once, using the MIT Integrated Global Systems Model.

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. The effects of ozone are decidedly different.

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.

Crops are hardest hit. Model predictions show that ozone levels tend to be highest in regions where crops are grown. In addition, crops are particularly sensitive to ozone, in part because they are fertilized.

When crops are fertilized, their stomata open up, and they suck in more air. And the more air they suck in, the more ozone damage occurs. It’s a little like going out and exercising really hard on a high-ozone day.

—John Reilly

Northern temperate regions generally benefit from climate change because higher temperatures extend their growing season. However, the crop losses associated with high ozone concentrations will be significant. In contrast, the tropics, already warm, do not benefit from further warming, but they are not as hard hit by ozone damage because ozone-precursor emissions are lower in the tropics.

The study thus concluded that regions such as the United States, China and Europe would need to import food, and supplying those imports would be a benefit to tropical countries.

Reilly warns that the study’s climate projections may be overly optimistic. The researchers are now incorporating a more realistic climate simulation into their analysis.

Reilly’s colleagues are from MIT and the Marine Biological Laboratory. The research was supported by the Department of Energy, the Environmental Protection Agency, the National Science Foundation, NASA, the National Oceanographic and Atmospheric Administration and the MIT Joint Program on the Science and Policy of Global Change.

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Comments

GreyFlcn

So much for basing our economy on growing crops for energy.

Patrick

Heck, if they don't cure CCD in bees we could very well lose 40% of our crops in 10 years regardless of ozone's effects 90 years down the road.

aym

So much for the advantages of the super-fertilization effect which were temporary I believe anyway. No only that, I read that although growth would go up, but nutritively the quality would go down. Overall, I'd say that puts it in the overall negative column.

i think the future of at least some type of aggriculture is in enclosed environments. tall buildings that take up a small foot print but can have acres of available "land" for growing crops. i would assume that in that environment air qulaity can be controlled.
too bad only the super rich will be able to afford the tomato.
and if that doesn't work we'll simply generically engineer ozone tollerant strains of popular crops.
a resourceful bunch humans are. I think we need to creat problems for us to solve, otherwise, what would we do all day....

Alain

Since ozone production is a 'side-effect' of fuel combustion, and fuel combustion will evidently be much lower by then, it is a silly idea to linearly extrapolate the current trents.
Additionally, since ozone and its precursors are very short-living molecules in the atmosphere, the pollution stops very quickly (within days) after the exhaust stops (contrary to CO2).
In addition, even fuel combustion can be done much cleaner, but it is not a priority at the moment. Importantly though, ethanol fumes can cause increased ozone production during sunny days. A good reason to go electric (or prevent ethanol fume escape).

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