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For further information, contact the MBL Communications Office at (508) 289-7423 or e-mail us at comm@mbl.edu
For Immediate Release: November 15, 2007
Contact: Gina Hebert, 508-289-7725; ghebert@mbl.edu
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Ozone Alert: “Business as Usual” in Fossil-Fuel Burning May Cause Major Damage to Crops
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Ben Felzer is a research associate at the MBL's Ecosystems Center
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MBL, WOODS HOLE, MA — Rising greenhouse gas levels and global temperatures will generally benefit crop yields worldwide, but those gains may be more than offset by the detrimental effects of ozone accumulating near the Earth’s surface, report scientists from the MBL Ecosystems Center and the MIT Joint Program on Science and Policy of Global Change.
Their study, published in the November issue of Energy Policy, predicts global crop yields will fall by nearly 40 percent by 2100 if no effort is made to limit the emission of greenhouse gases and ozone precursors, which are released by fossil-fuel burning.
“Ozone has a hugely detrimental effect on crops,” says Ben Felzer, a research associate at the Ecosystems Center, whose work in recent years introduced the important factor of ozone into climate-change models. Ozone (O3) is an air pollutant that inhibits photosynthesis in plants, and therefore reduces vegetation production and carbon sequestration.
Dramatic drops in crop yield will translate to more modest drops (9 percent at most) in food production, the study predicts, because the world will adapt by allocating more resources to growing food. “There will be land-use substitutions,” Felzer says. “More land will be used for crop production at the expense of forestry and pasture. So the negative effect of ozone on crops is felt beyond the agricultural sector.”
If fossil-fuel burning continues as “business as usual,” the areas hardest hit by ozone damage are predicted to be the northern mid-latitudes, including the U.S. Midwest, where ozone levels are high and fertilized agricultural areas are extensive. (The ozone effect is larger on fertilized lands, because the effect is proportional to the land’s productivity.) In contrast, Canada, Latin America, Africa, Australia and New Zealand – where ozone emissions are lower – could economically benefit from a high pollution, non-emissions-capped scenario, as they could export food to damaged areas.
“Controlling greenhouse gases not only is beneficial for limiting global warming, but it also helps control ozone levels and therefore improves future crop yield and production,” Felzer says.
The study, led by John Reilly of MIT, uses the MIT Integrated Global System Model to examine how changes in climate, carbon dioxide, and tropospheric ozone affect crop, pasture and forest land productivity, and the consequences for global and regional economies. One important component of this integrated model is the Terrestrial Ecosystems Model (TEM), which was introduced in the early 1990s by the MBL’s Jerry Melillo and colleagues at the Ecosystems Center. TEM simulates the cycling of carbon, nitrogen and water between vegetation, soils and the atmosphere; the model is calibrated against field data collected from 10 different biomes around the world. Felzer updated TEM in 2004 to include ozone effects. Another important component of the MIT model is the Emissions Prediction and Policy Analysis Model (EPPA), which analyzes global economic growth, international trade, greenhouse gas emissions and the effects of policies to limit those emissions.
“The MIT model is innovative because it integrates economic policy with natural carbon fluxes from the terrestrial ecosystems to determine changes in land cover and land use,” Felzer says.
The TEM group at the MBL (Jerry Melillo, David Kicklighter, Timothy Cronin, as well as Felzer) is currently looking at how biofuels initiatives – such as the production of ethanol from corn, which will require land-use changes – may factor into global climate change. “The approach we developed in the Energy Policy paper of using TEM yield to factor back into EPPA is now being used to determine land use/land cover changes that will be necessary to achieve certain biofuel targets in the context of changing climate and increasing carbon dioxide levels, “ he says. “We are specifically looking at transitions between cropland, pastureland, managed forest, unmanaged forest, and unmanaged grassland.”
The MBL is a leading international, independent, nonprofit institution dedicated to discovery and to improving the human condition through creative research and education in the biological, biomedical and environmental sciences. Founded in 1888 as the Marine Biological Laboratory, the MBL is the oldest private marine laboratory in the Western Hemisphere. For more information, visit www.MBL.edu
The research of the MBL's Ecosystems Center, which was established at the MBL in 1975, is focused on the study of natural ecosystems. Among the key environmental issues being addressed are: the ecological consequences of global climate change; tropical deforestation and its effects on greenhouse gas fluxes; nitrogen saturation of mid-latitude forests; effects of acid rain on North American lakes; and pollution and habitat destruction in coastal ecosystems of the United States.
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