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Livestock Contributes to Global Warming

Article Commentary

Robert Goodland and Jeff Anhang, “Livestock and Climate Change,” World Watch, November/December 2009, pp. 11-16. Copyright © 2009 World Watch Institute. All rights reserved. Reproduced with permission.

Robert Goodland is retired from his twenty-three-year position as lead environmental adviser at the World Bank Group. Jeff Anhang is aresearch officer and environmental specialist at the World Bank Group’s International Finance Corporation.

Whenever the causes of climate change are discussed, fossil fuels top the list. Oil, natural gas, and especially coal are indeed major sources ofhuman-caused emissions of carbon dioxide (CO2) and other greenhouse gases (GHGs). But we believe that the life cycle and supply chain ofdomesticated animals raised for food have been vastly underestimated as a source of GHGs, and in fact account for at least half of all human-caused GHGs. If this argument is right, it implies that replacing livestock products with better alternatives would be the best strategy for reversingclimate change. In fact, this approach would have far more rapid effects on GHG emissions and their atmospheric concentrationsandthus on the rate the climate is warmingthan actions to replace fossil fuels with renewable energy.

Livestock are already well-known to contribute to GHG emissions. Livestock’s Long Shadow, the widely-cited 2006 report by the United Nations Food and Agriculture Organization (FAO), estimates that 7,516 million metric tons per year of CO2 equivalents (CO2e), or 18 percent of annualworldwide GHG emissions, are attributable to cattle, buffalo, sheep, goats, camels, horses, pigs, and poultry. That amount would easily qualifylivestock for a hard look indeed in the search for ways to address climate change. But our analysis shows that livestock and their byproductsactually account for at least 32,564 million tons of CO2e per year, or 51 percent of annual worldwide GHG emissions.

This is a strong claim that requires strong evidence, so we will thoroughly review the direct and indirect sources of GHG emissions fromlivestock. Some of these are obvious but underestimated, some are simply overlooked, and some are emissions sources that are alreadycounted but have been assigned to the wrong sectors. Data on livestock vary from place to place and are affected by unavoidableimprecision; where it was impossible to avoid imprecision in estimating any sum of GHGs, we strove to minimize the sum so our overall estimate could be understood as conservative.

Livestock (like automobiles) are a human invention and convenience, not part of pre-human times, and a molecule of CO2 exhaled by livestock is no more natural than one from an auto tailpipe.

The Big Picture

[According to the FAO] 7,516 million tons of CO2e per year [is] attributable to livestock, an amount established by adding up GHG emissionsinvolved in clearing land to graze livestock and grow feed, keeping livestock alive, and processing and transporting the end products. We showthat 25,048 million tons of CO2e attributable to livestock have been undercounted or overlooked; of that subtotal, 3,000 million tons are misallocated and 22,048 million tons are entirely uncounted. When uncounted tons are added to the global inventory of atmospheric GHGs, thatinventory rises from 41,755 million tons to 63,803 million tons. FAO’s 7,516 million tons of CO2e attributable to livestock then decline from 18percent of worldwide GHGs to 11.8 percent. Let’s look at each category of uncounted or misallocated GHGs:

Breathing

The FAO excludes livestock respiration from its estimate, per the following argument:

Respiration by livestock is not a net source of CO2Emissions from livestock respiration are part of a rapidly cycling

biological system, where the plant matter consumed was itself created through the conversion of atmospheric CO2 into organiccompounds. Since the emitted and absorbed quantities are considered to be equivalent, livestock respiration is not considered tobe a net source under the Kyoto Protocol. Indeed, since part of the carbon consumed is stored in the live tissue of the growing animal, a growing global herd could even be considered a carbon sink. The standing stock livestock biomass increasedsignificantly over the last decades…. This continuing growthcould be considered as a

carbon sequestration process (roughly estimated at 1 or 2 million tons carbon per year).

But this is a flawed way to look at the matter. Examining the sequestration claim first: Sequestration properly refers to extraction of CO2 from theatmosphere and its burial in a vault or a stable compound from which it cannot escape over a long period of time. Even if one considers thestanding mass of livestock as a carbon sink, by the FAO’s own estimate the amount of carbon stored in livestock is trivial compared to theamount stored in forest cleared to create space for growing feed and grazing livestock.

More to the point, livestock (like automobiles) are a human invention and convenience, not part of pre-human times, and a molecule of CO2exhaled by livestock is no more natural than one from an auto tailpipe. Moreover, while over time an equilibrium of CO2 may exist between theamount respired by animals and the amount photosynthesized by plants, that equilibrium has never been static. Today, tens of billions morelivestock are exhaling CO2 than in preindustrial days, while Earth’s photosynthetic capacity (its capacity to keep carbon out of the atmosphere byabsorbing it in plant mass) has declined sharply as forest has been cleared. (Meanwhile, of course, we add more carbon to the air by burningfossil fuels, further overwhelming the carbon-absorption system.)

Carbon dioxide from livestock respiration accounts for 21 percent of anthropogenic GHGs worldwide.

The FAO asserts that livestock respiration is not listed as a recognized source of GHGs under the Kyoto Protocol, although in fact the Protocol does list CO2 with no exception, and “other” is included as a catchall category. For clarity, it should be listed separately in whatever protocol replaces Kyoto.

It is tempting to exclude one or another anthropogenic [human-made] source of emissions from carbon accountingaccording to one’sown interestson the grounds that it is offset by photosynthesis. But if it is legitimate to count as GHG sources fossil-fuel- drivenautomobiles, which hundreds of millions of people do not drive, then it is equally legitimate to count livestock respiration. Little or no livestock product is consumed by hundreds of millions of humans, and no livestock respiration (unlike human respiration) is needed for human survival.By keeping GHGs attributable to livestock respiration off GHG balance sheets, it is predictable that they will not be managed and their amountwill increaseas in fact is happening.

Carbon dioxide from livestock respiration accounts for 21 percent of anthropogenic GHGs worldwide, according to a 2005 estimate by British physicist Alan Calverd. He did not provide the weight of this CO2, but it works out to about 8,769 million tons. Calverd’s estimate is the only original estimate of its type, but because it involves only one variable (the total mass of all livestock, as all but cold-blooded farmed fish exhale roughly the same amount of CO2 per kilogram), all calculations of CO2 from the respiration of a given weight of livestock would be about thesame.

Calverd’s estimate did not account for the fact that CO2 from livestock respiration is excluded from global GHG inventories. It also did not accountfor the GHGs newly attributed to livestock in our analysis. After adding all relevant GHGs to global GHG inventories, the percentage of GHGsattributable to livestock respiration drops from 21 percent to 13.7 percent.

Land

As there is now a global shortage of grassland, practically the only way more livestock and feed can be produced is by destroying naturalforest. Growth in markets for livestock products is greatest in developing countries, where rainforest normally stores at least 200 tons of carbon per hectare. Where forest is replaced by moderately degraded grassland, the tonnage of carbon stored per hectare is reduced to 8.

On average, each hectare of grazing land supports no more than one head of cattle, whose carbon content is a fraction of a ton. In comparison, over 200 tons of carbon per hectare may be released within a short time after forest and other vegetation are cut, burned, or chewed. From the soil beneath, another 200 tons per hectare may be released, with yet more GHGs from livestock respiration and excretions. Thus, livestock of alltypes provide minuscule carbon “piggybanks” to replace huge carbon stores in soils and forests. But if the production of livestock or crops isended, then forest will often regenerate. The main focus in efforts to mitigate GHGs has been on reducing emissions, whiledespite itsability to mitigate GHGs quickly and cheaplyvast amounts of potential carbon absorption by trees has been foregone.

The FAO counts emissions attributable to changes in land use due to the introduction of livestock, but only the relatively small amount of GHGs from changes each year. Strangely, it does not count the much larger amount of annual GHG reductions from photosynthesis that are foregone by using 26 percent of land worldwide for grazing livestock and 33 percent of arable land for growing feed, rather than allowing it to regenerate forest. By itself, leaving a significant amount of tropical land used for grazing livestock and growing feed to regenerate as forest could potentially mitigate as much as half (or even more) of all anthropogenic GHGs. A key reason why this is not happening is that reclaiming land used forgrazing livestock and growing feed is not yet a priority; on the contrary, feed production and grazing have been fast expanding into forest.

A significant reduction in livestock raised worldwide would reduce GHGs relatively quickly compared with measures involving renewable energy and energy efficiency.

Or suppose that land used for grazing livestock and growing feed were used instead for growing crops to be converted more directly to food for humans and to biofuels. Those fuels could replace one-half of the coal used worldwide, which is responsible for about 3,340 million tons of CO2eemissions every year. That tonnage represents 8 percent of GHGs in worldwide GHG inventories that omit the additional GHGs assessed by thisarticle, or 5.6 percent of GHGs worldwide when the GHGs assessed in this article are included. If biomass feedstocks are chosen and processedcarefully, then biofuels can yield 80 percent less GHGs per unit of energy than coal. Therefore, the extra emissions resulting from using land forlivestock and feed can be estimated to be 2,672 million tons of CO2e, or

4.2 percent of annual GHG emissions worldwide.

Considering these two plausible scenarios, at least 4.2 percent of worldwide GHGs should be counted as emissions attributable to GHG reductions foregone by using land to graze livestock and grow feed.

Methane

According to the FAO, 37 percent of human-induced methane comes from livestock. Although methane warms the atmosphere much morestrongly than does CO2, its half-life in the atmosphere is only about 8 years, versus at least 100 years for CO2. As a result, a significant reduction in livestock raised worldwide would reduce GHGs relatively quickly compared with measures involving renewable energy and energy efficiency.

We calculate that the increase in livestock products worldwide from 2002 to 2009 accounts for about 2,560 million tons of CO2e, or 4.0 percent of GHG emissions.

The capacity of greenhouse gases to trap heat in the atmosphere is described in terms of their global warming potential (GWP), which compares their warming potency to that of CO2 (with a GWP set at 1). The new widely accepted figure for the GWP of methane is 25 using a100-year timeframebut it is 72 using a 20-year timeframe, which is more appropriate because of both the large effect that methane reductions can have within 20 years and the serious climate disruption expected within 20 years if no significant reduction of GHGs is achieved.The Intergovernmental Panel on Climate Change supports using a 20-year timeframe for methane.

The FAO estimates that livestock accounted for 103 million tons of methane emissions in 2004 through enteric fermentation and manure management, equivalent to 2,369 million tons of CO2e. This is 3.7 percent of worldwide GHGs using, as FAO does, the outdated GWP of 23. Using a GWP of 72, livestock methane is responsible for 7,416 million tons of CO2e or 11.6 percent of worldwide GHGs. So using theappropriate timeframe of 20 years instead of 100 years for methane raises the total amount of GHGs attributable to livestock products by 5,047 million tons of CO2e or 7.9 percentage points. (Further work is needed to recalibrate methane emissions other than those attributable tolivestock products using a 20-year timeframe.)

Other sources

Four additional categories of GHGs adding up to at least 5,560 million tons of CO2e (8.7 percent of GHGs emissions) have been overlooked or undercounted by the FAO and uncounted in the existing inventory of worldwide GHGs:

First, Livestock’s Long Shadow cites 2002 FAO statistics as the key source for its 18-percent estimate. From 2002 to 2009, the tonnage of livestock products worldwide increased by 12 percent, which must yield a proportional increase in GHG emissions. Through extrapolationfrom the FAO’s estimate as well as our own, we calculate that the increase in livestock products worldwide from 2002 to 2009 accounts forabout 2,560 million tons of CO2e, or 4.0 percent of GHG emissions.

Second, the FAO and others have documented frequent undercounting in official statistics of both pastoral and industrial livestock. Livestock’s Long Shadow not only uses no correction factor for such undercounting, but in some sections actually uses lower numbers than appear in FAOstatistics and elsewhere. For example, Livestock’s Long Shadow reports that 33.0 million tons of poultry were produced worldwide in 2002, while FAO’s Food Outlook of April 2003 reports that 72.9 million tons of poultry were produced worldwide in 2002. The report also states that 21.7 billion head of livestock were raised worldwide in 2002, while many nongovernmental organizations report that about 50 billion head of livestock were raised each year in the early 2000s. If the true number is closer to 50 billion than to 21.7 billion, then the percentage of GHGs worldwide attributable to undercounting in official livestock statistics would likely be over 10 percent.

Third, the FAO uses citations for various aspects of GHGs attributable to livestock dating back to such years as 1964, 1982, 1993, 1999, and 2001. Emissions today would be much higher.

Fourth, the FAO cites Minnesota as a rich source of data. But if these data are generalized to the world then they understate true values, asoperations in Minnesota are more efficient than operations in most developing countries where the livestock sector is growing fastest.

Finally, we believe that FAO has overlooked some emissions that have been counted under sectors other than livestock. These emissionsadd up to at least 3,000 million tons of CO2e, or 4.7 percent of GHG emissions worldwide.

An effective strategy must involve replacing livestock products with better alternatives, rather than substituting one meat product with another that has a somewhat lower carbon footprint.

First, the FAO states that “livestock-related deforestation as reported from, for example, Argentina is excluded” from its GHG accounting.Second, the FAO omits farmed fish from its definition of livestock and so fails to count GHGs from their life cycle and supply chain. It alsoomits GHG emissions from portions of the construction and operation of marine and land-based industries dedicated to handling marineorganisms destined to feed livestock (up to half the annual catch of marine organisms).

Lastly, the FAO leaves uncounted the substantially higher amount of GHGs attributable to each of the following aspects of livestock products versus alternatives to livestock products:

Fluorocarbons (needed for cooling livestock products much more than alternatives), which have a global warming potential up to several thousand times higher than that of CO2.

Cooking, which typically entails higher temperatures and longer periods for meat than alternatives, and in developing countriesentails large amounts of charcoal (which reduces carbon absorption by consuming trees) and kerosene, each of which emits high levels of GHGs.

Disposal of inevitably large amounts of liquid waste from livestock, and waste livestock products in the form of bone, fat, and spoiledproducts, all of which emit high amounts of GHGs when disposed in landfills, incinerators, and waterways.

Production, distribution, and disposal of byproducts, such as leather, feathers, skin, and fur, and their packaging. Production,distribution, and disposal of packaging used for livestock products, which for sanitary reasons is much more extensive than for alternatives to livestock products.

Carbon-intensive medical treatment of millions of cases worldwide of zoonotic illnesses (such as swine flu) and chronic degenerativeillnesses (such as coronary heart disease, cancers, diabetes, and hypertension leading to strokes) linked to the consumption of livestock products. Full accounting of GHGs attributable to livestock products would cover portions of the construction and operation ofpharmaceutical and medical industries used to treat these illnesses.

A key risk factor for climate change is the growth of the human population, projected to be roughly 35 percent between 2006 and 2050. In thesame period, the FAO projects that the number of livestock worldwide will double, so livestock-related GHG emissions would alsoapproximately double (or rise slightly less if all the FAO’s recommendations were fully implemented), while it is widely expected that GHGs from other industries will drop. This would make the amount