A Global Diet on Livestock Emissions
by Bill Chameides | November 10th, 2009
posted by Erica Rowell (Editor)
In the search for low-hanging fruit in climate mitigation strategies, are emissions reductions from livestock rearing being considered?
You’ve heard about REDD, the program to “reduce emissions from deforestation and degradation.” Why not RECC, an effort to Reduce Emissions from Cows and Cattle?
About 77 percent of the total emissions are in the form of carbon dioxide, but other gases are important. Emissions of methane (CH4) account for about 15 percent of the total, and nitrous oxide (N2O) emissions make up another eight percent of the GHG pie. (See graph below.)
Overhauling Energy Sources Must Play Big Role in Tackling Climate Change
The major contributor to CO2 emissions comes from burning fossil fuels — some 57 percent of the 40 billion tons cited above. So climate change mitigation will require a major alteration in the way we produce energy to power our cars, our homes, and our factories. To succeed in slowing and then ultimately reducing global emissions of greenhouse gases will require:
Global Anthropogenic Greenhouse Gas Emissions in 2004. Note: Other CO2 includes cement production and natural gas flaring. (Source IPCC)
- new low-carbon technologies,
- a greater reliance on renewable energy, and
- a greater focus on efficiency.
But revamping the world’s energy infrastructure is no simple task. Here are just three complications:
• We’ve already made enormous investments in fossil-fuel intensive facilities;
• Low-carbon replacements are, in many cases, still in the development phase; and
• Integrating available renewable energy sources such as wind is problematic because of limitations of our electric grid.
And so policy makers have been looking for emissions from so-called low-hanging fruit outside the energy sector — not as a substitute for cutting energy emissions but as a way to jump-start reductions while we tool up to make the more difficult energy-related cuts.
The Low-Hanging Fruit of Trees
One example is emissions from deforestation and forest degradation. According to a recent paper in Nature Geosciences, emissions from the destruction and degradation of tropical rain forests amount to about 12 percent of the total global greenhouse emissions; including emissions from burning peatlands increases that slice of the pie to about 15 percent.
The REDD program, up for consideration at next month’s climate talks in Copenhagen as part of the next global climate agreement, would address these emissions by providing a mechanism for developed economies to offset their emissions by paying the topical rain forest nations to slow their destruction of these unique and valuable ecosystems. Great idea.
But if emissions from deforestation are a good target, why not also take aim at emissions from livestock?
The Low-Hanging Fruit of Cattle
We all know that we raise a lot of animals to feed a world of almost seven billion. But do you know how many? According to a U.N. report, there are about 1.5 billion cattle and buffalo, 1.8 billion small ruminants, almost 1 billion pigs, and a whopping 17.4 billion poultry birds. Think about it — for every person on the earth, that’s about a quarter of a cow or its equivalent, a seventh of a pig, and 2.5 feathered friends.
Given those numbers, it’s not too surprising that livestock turn out to be directly or indirectly responsible for a whole lot of greenhouse gas emissions. Here are some numbers from that same U.N. report.
- CH4 emissions from enteric fermentation amount to about 2 billion tons of CO2 equivalents per year or about 6 percent of the total global greenhouse gas emissions.
- N2O emissions mostly from the decay of manure amounts to another 2 billion tons of CO2 equivalents per year.
- CO2 emissions from the production of the energy needed to support the livestock industry worldwide is small — less than 0.2 billion tons per year.
- But CO2 emissions from land use change (e.g., destruction of forests and grasslands) to raise cattle are estimated at 2.7 billion tons of CO2 or 8 percent of the total.
All told, estimates by the U.N.’s Food and Agriculture Organization put livestock production and management at about seven billion tons of CO2 equivalents per year — that’s more than 20 percent of the total greenhouse gas emissions.
If we leave out the emissions from land use change change (which is largely contained in the numbers for deforestation and forest degradation), livestock emissions still amount to about 4.6 billion tons per year or 14 percent of the total.
The Low-Hanging Fruit Not Being Considered Ripe for Plucking
Though greenhouse emissions from livestock look to be as large as or even larger than those from deforestation and forest degradation, because they are related to agricultural activities, most animal-production emissions (like those from deforestation and forest degradation) will not be included in a national or international emissions cap.
But unlike deforestation and forest degradation which will have its REDD program, no similar program, like one to Reduce Emissions from Cows and Cattle, appears to be on the horizon.
But why not? There are things farmers can do to cut livestock emissions. (Check out this recent New York Times op-ed.) Here are some examples:
- Changing the diet of cattle: Some evidence suggests that feeding cattle with grass instead of grains can reduce methane emissions from enteric fermentation. Replacing grain feeds with grass eliminates the emissions related to cultivating and harvesting grains; less fossil fuels to drive the tractors, less N20 emissions from fertilizers, less water for irrigation.
- Genetic modification: There’s potential for using genetic modification to develop cows that produce less methane.
- Manure: Better waste management can reduce or eliminate the emissions of nitrous oxide and methane.
In the meantime, we must begin cutting greenhouse gas emissions, and given the difficulties we face in accomplishing this, we can’t afford to give a free pass to a sector of the global system that’s responsible for 14 percent or more of the total emissions. Not including something like RECC would be rather, ah, reckless.filed under: animals, carbon dioxide emissions, climate change, deforestation, faculty, forests, fossil fuels, methane, waste
and: cows, greenhouse gas emissions, meat, nitrogen oxides, REDD