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FoodGlobal Warming

Question: How to Curb CO2 Emissions and Feed the World?

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Answer: Increase Crop Yields.

Efforts to mitigate greenhouse gas (GHG) emissions are being discussed, and sometimes initiated, with greater urgency these days. As questions on cost-effectiveness also loom, attention has naturally turned to agriculture, a major source of carbon emissions.

These emissions are primarily the result of animal livestock, fertilizers and heavy machinery (the latter two being necessary for any large crop output), with additional carbon loss resulting from over-tilling of crop lands.

In a recent paper published on the Proceedings of the National Academy of Sciences website (Greenhouse gas mitigation by agricultural intensification, by Jennifer A. Burney, Steven J. Davis, and David B. Lobell), the authors estimated the GHG emissions from U.S. agriculture for the period from 1961 through 2005–a period of great agricultural intensification–and show a massive decrease in GHG emissions as a result of this intensification.

The authors of a new study on agricultural practices show that increasing crop yields significantly reduces CO2 emissions, and, they advocate investment in agriculture research as a top mitigation strategy.

Specifically, the researchers calculated that up to 161 gigatons of carbon (GtC) emissions (which converts to 590 Gigatons of  CO2) were avoided, since 1961, due to this expanded and technologically improved agricultural “push”. This, even despite the increased production and application of petrochemical fertilizers to aid higher crop yields.

Further, according to the authors: “We estimate that each dollar invested in agricultural yields has resulted in 68 fewer kgC (249 kgCO2e) emissions relative to 1961 technology ($14.74/tC, or ~$4/tCO2e), avoiding 3.6 GtC (13.1 GtCO2e) per year.”

This estimate is based on a comparison to traditional forms of agricultural practice. Such intensification efforts can also address an additional, and no less important, issue: that of improving global food security.

Global agricultural output for 2005

The authors do acknowledge the undesirable environmental consequences that agricultural intensification and extensification will likely produce, such as the spreading of fertilizers and pesticides to surrounding ecosystems, as well as the potential biodiversity loss due to land-use changes. It should be noted that the authors advocate intensification over expanding farmlands to achieve the desired CO2 mitigation effects.

The researchers also note that their estimates of emissions from land use change “exclude pasture land and areas dedicated to biofuels, and neglect the projected increase in dietary preference for meat as per capita GDP grows.”

Quoting from the paper abstract: “Our analysis indicates that investment in yield improvements compares favorably with other commonly proposed mitigation strategies. Further yield improvements should therefore be prominent among efforts to reduce future GHG emissions.”

Writer’s Note:

Many new research centers and programs have been initiated around the world. One prominent example is the ICRISAT Sadore research station. which does extensive research on legumes–a cheap, quality source of protein for many developing nations–amongst other crops. Legumes are also “nitrogen fixers” and prevent the release of ozone depleting nitrogen compounds into the atmosphere

Top photo: USAID

Chart: public domain (CIA)




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