A New Global Warming Strategy
How Environmentalists are Overlooking
Vegetarianism as the Most Effective Tool
Against Climate Change in Our Lifetimes
by Noam Mohr
An EarthSave International Report
A New Global Warming Strategy:
How Environmentalists are Overlooking Vegetarianism as the Most Effective Tool
Against Climate Change in Our Lifetimes
Global warming poses one of the most serious threats to the global environment ever faced
in human history. Yet by focusing entirely on carbon dioxide emissions, major
environmental organizations have failed to account for published data showing that other
gases are the main culprits behind the global warming we see today. As a result, they are
neglecting what might be the most effective strategy for reducing global warming in our
lifetimes: advocating a vegetarian diet.
Global Warming and Carbon Dioxide process.8 His results are generally accepted by
global warming experts, including bigwigs like
The environmental community rightly recognizes
Dr. James McCarthy, co-chair of the
global warming as one of the gravest threats to
International Panel on Climate Change’s
the planet. Global temperatures are already
Working Group II.9
higher than they’ve ever been in at least the past
millennium,1 and the increase is accelerating
The focus solely on CO2 is fueled in part by
even faster than scientists had predicted.2 The
misconceptions. It’s true that human activity
expected consequences include coastal flooding,
produces vastly more CO2 than all other
increases in extreme weather, spreading disease,
greenhouse gases put together. However, this
and mass extinctions.
does not mean it is responsible for most of the
Unfortunately, the environmental earth’s warming. Many
community has focused its efforts Sources of non-CO2 green- other greenhouse gases trap
almost exclusively on abating house gases are responsible heat far more powerfully
than CO2, some of them
carbon dioxide (CO2) emissions.
Domestic legislative efforts
for virtually all the global tens of thousands of times
concentrate on raising fuel warming we are going to more powerfully.10 When
economy standards, capping CO2 see for the next half century. taking into account various
emissions from power plants, and gases’ global warming
investing in alternative energy sources. potential—defined as the amount of actual
Recommendations to consumers also focus on warming a gas will produce over the next one
CO2: buy fuel-efficient cars and appliances, and hundred years—it turns out that gases other than
minimize their use. 3,4 CO2 make up most of the global warming
This is a serious miscalculation. Data published
by Dr. James Hansen and others5 show that CO2 Even this overstates the effect of CO2, because
emissions are not the main cause of observed the primary sources of these emissions—cars and
atmospheric warming. Though this may sound power plants—also produce aerosols. Aerosols
like the work of global warming skeptics, it isn’t: actually have a cooling effect on global
Hansen is Director of NASA’s Goddard Institute temperatures, and the magnitude of this cooling
for Space Studies who has been called “a approximately cancels out the warming effect of
grandfather of the global warming theory.” He is CO2.12 The surprising result is that sources of
a longtime supporter of action against global CO2 emissions are having roughly zero effect on
warming, cited by Al Gore and often quoted by global temperatures in the near-term!13
environmental organizations, who has argued
This result is not widely known in the
against skeptics for subverting the scientific
environmental community, due to a fear that natural sources.21 In fact, the effect of our
polluting industries will use it to excuse their methane emissions may be compounded as
greenhouse gas emissions. For example, the methane-induced warming in turn stimulates
Union of Concerned Scientists had the data microbial decay of organic matter in wetlands—
reviewed by other climate experts, who affirmed the primary natural source of methane.22
Hansen’s conclusions.14 However, the
organization also cited climate contrarians’ With methane emissions causing nearly half of
misuse of the data to argue against curbs in the planet’s human-induced warming, methane
CO2.15 This contrarian spin cannot be justified. reduction must be a priority. Methane is
produced by a number of sources, including coal
While CO2 may have little influence in the near- mining and landfills—but the number one source
term, reductions remains critical for containing worldwide is animal agriculture.23 Animal
climate change in the long run. Aerosols are agriculture produces more than 100 million tons
short-lived, settling out of the air after a few of methane a year.24 And this source is on the
months, while CO2 continues to heat the rise: global meat consumption has increased
atmosphere for decades to fivefold in the past fifty
centuries. Moreover, we By far the most important years, and shows little sign of
cannot assume that aerosol abating.25 About 85% of this
emissions will keep pace with
non-CO2 greenhouse gas is methane is produced in the
increases in CO2 emissions. 16 methane, and the number one digestive processes of
If we fail start dealing with source of methane worldwide livestock, and while a
CO2 today, it will be too late single cow releases a
down the road when the
is animal agriculture. relatively small amount of
emissions catch up with us. methane,27 the collective
effect on the environment of the hundreds of
Nevertheless, the fact remains that sources of millions of livestock animals worldwide is
non-CO2 greenhouse gases are responsible for enormous. An additional 15% of animal
virtually all the global warming we’re seeing, and agricultural methane emissions are released from
all the global warming we are going to see for the the massive “lagoons” used to store untreated
next fifty years. If we wish to curb global farm animal waste,28 and already a target of
warming over the coming half century, we must environmentalists’ for their role as the number
look at strategies to address non-CO2 emissions. one source of water pollution in the U.S.29
The strategy with the most impact is
vegetarianism. The conclusion is simple: arguably the best way
to reduce global warming in our lifetimes is to
Methane and Vegetarianism reduce or eliminate our consumption of animal
products. Simply by going vegetarian (or, strictly
By far the most important non-CO2 greenhouse
speaking, vegan),30,31,32 we can eliminate one of
gas is methane, and the number one source of
the major sources of emissions of methane, the
methane worldwide is animal agriculture.17
greenhouse gas responsible for almost half of the
Methane is responsible for nearly as much global global warming impacting the planet today.
warming as all other non-CO2 greenhouse gases
put together.18 Methane is 21 times more Advantages of Vegetarianism over
powerful a greenhouse gas than CO2. While19 CO2 Reduction
atmospheric concentrations of CO2 have risen by In addition to having the advantage of
about 31% since pre-industrial times, methane immediately reducing global warming, a shift
concentrations have more than doubled.20 away from methane-emitting food sources is
Whereas human sources of CO2 amount to just much easier than cutting carbon dioxide.
3% of natural emissions, human sources produce
one and a half times as much methane as all First, there is no limit to reductions in this source
of greenhouse gas that can be achieved through major appliance, most people wanting to make a
vegetarian diet. In principle, even 100% difference are given little to do aside from
reduction could be achieved with little negative writing their legislators and turning off their
impact. In contrast, similar cuts in carbon dioxide lights. Reducing or eliminating meat
are impossible without devastating effects on the consumption is something concerned citizens can
economy. Even the most ambitious carbon do every day to help the planet.
dioxide reduction strategies fall short of cutting
emissions by half. Finally, it is worth noting that reductions in this
source of greenhouse gas have many beneficial
Second, shifts in diet lower greenhouse gas side effects for the environment. Less methane
emissions much more quickly than shifts away results in less tropospheric ozone, a pollutant
from the fossil fuel burning technologies that damaging to human health and agriculture.33
emit carbon dioxide. The turnover rate for most Moreover, the same factory farms responsible for
ruminant farm animals is one or two years, so these methane emissions also use up most of the
that decreases in meat consumption would result country’s water supply, and denude most of its
in almost immediate drops in wilderness for rangeland and
methane emissions. The Methane cycles out of the growing feed. Creating
turnover rate for cars and
power plants, on the other atmosphere in just 8 years, rangeland to feed appetite for
hand, can be decades. Even if so reducing meat consump- meat has been a major source
cheap, zero-emission fuel tion quickly translates to of deforestation and
sources were available today, desertification in third world
they would take many years to
cooling of the earth.
countries. Factory farm waste
build and slowly replace the lagoons are a leading source of
massive infrastructure our economy depends water pollution in the U.S. Indeed, because of
upon today. animal agriculture’s high demand for fossil fuels,
the average American diet is far more CO2-
Similarly, unlike carbon dioxide which can polluting than a plant-based one.34
remain in the air for more than a century,
methane cycles out of the atmosphere in just
eight years, so that lower methane emissions Recommendations
quickly translate to cooling of the earth.
• Organizations should consider making
Third, efforts to cut carbon dioxide involve advocating vegetarianism a major part of their
fighting powerful and wealthy business interests global warming campaigns. At a minimum,
like the auto and oil industries. Environmental environmental advocates should mention
groups have been lobbying for years to make vegetarianism in any information about actions
fuel-efficient SUVs available or phase out power individuals can take to address global warming.
plants that don’t meet modern environmental
standards without success. At the same time, • Government policy should encourage
vegetarian foods are readily available, and cuts in vegetarian diets. Possible mechanisms include an
agricultural methane emissions are achievable at environmental tax on meat similar to one already
every meal. recommended on gasoline, a shift in farm
subsidies to encourage plant agriculture over
Also, polls show that concern about global animal agriculture, or an increased emphasis on
warming is widespread, and environmental vegetarian foods in government-run programs like
activists often feel helpless to do anything about the school lunch program or food stamps.
it. Unless they happen to be buying a car or
Mann, Michael E. et al., “Northern Hemisphere Moser, Susi, “Review of Hansen et al.: ‘Global
Temperatures During the past Millennium: warming in the twenty-first century: An alternative
Inferences, Uncertainties, and Limitations”, scenario’”, Information Update, The Union of
Geophysical Research Letters, Vol. 26, No. 6, 1999, Concerned Scientists, September 2000, p.2,
p. 759-762, http://www.ngdc.noaa.gov/paleo/pubs/ http://www.ucsusa.org/documents/reviewofalt.pdf.
mann_99.html. SF6 has a global warming potential 23,900 times
“Global warming may be accelerating,” USA Today, that of carbon dioxide. HFC-23 has a global warming
17 Mar. 2000, http://www.usatoday.com/weather/ potential 11,700 times that of carbon dioxide.
news/2000/wgblwrm.htm. “Global Warming Potentials”, National Emissions,
Some examples: U.S. PIRG’s global warming site U.S. Environmental Protection Agency,
(http://uspirg.org/uspirg.asp?id2=5235) advocates http://www.epa.gov/nonco2/econ-inv/table.html.
increasing fuel efficiency standards, capping CO2 Hansen, James E. and Makiko Sato, “Trends of
from power plants, shifting investments from fossil measured climate forcing agents”, Proceedings of the
fuels, and ratifying the Kyoto Protocol. The Sierra National Academy of Sciences, vol. 98, no. 26, 18
Club global warming site (http://www.sierraclub.org/ Dec. 2001, p. 14778-14783, http://www.pnas.org/cgi/
globalwarming/overview/solutions.asp) advocates content/full/98/26/14778. The estimated climate
energy efficiency in cars, power plants, and forcing of carbon dioxide from 1850 to 2000 is 1.4
increasing solar and wind energy. The Natural W/m2, while the combined forcings of methane,
Resources Defense Council (http://www.nrdc.org/ CFCs, nitrous oxide, and tropospheric ozone is 1.6
globalWarming/gsteps.asp) recommends energy- W/m2 when indirect effects via water and ozone are
efficient appliances, fuel efficient cars, compact taken into account.
fluorescent light bulbs, planting trees, weatherizing Hansen and Sato, supra note 11. Estimated climate
your home, and contacting your representatives. The forcing of aerosols from 1850 to 2000, is -1.5 W/m2,
Union of Concerned Scientists’ site larger than the positive forcing of carbon dioxide.
(http://www.ucsusa.org) recommends curbing our Admittedly, estimates of aerosol forcing have large
consumption of fossil fuels, using technologies that uncertainties; however, there are as likely to be too
reduce emissions, and protecting the world’s forests. low as too high. Among aerosols, black carbon
It’s worth noting that buying fuel efficient cars and warms the atmosphere, both by absorbance and
light trucks do not directly reduce carbon dioxide through semi-direct dirty cloud and snow effects,
emissions. Because auto manufacturers are bound while sulfates, nitrates, and organic aerosols have a
only by fleet-wide averages, every low-gas-mileage cooling effect, both by directly reflecting sunlight
car sold simply allows them to sell another gas and by indirectly making clouds less bright and
guzzler. However, choosing efficiency is not for reducing cloud cover. Hansen, et al., supra note 5.
naught: demand for fuel efficiency may help drive However, Hansen points out that “Offsetting of
technological innovation and reduce industry global mean forcings does not imply that climate
opposition to improved fuel economy standards. effects are negligible.” Hansen, et al., supra note 5.
Moreover, since cars have stricter standards than Moser, p. 1-2, supra note 9.
light trucks, it is always better to buy the former. Moser, p. 4, supra note 9.
Hansen, James E. et al., “Global warming in the Hansen, et al., supra note 5.
twenty-first century: An alternative scenario,” Animal agriculture is also a major source of nitrous
Proceedings of the National Academy of Sciences, oxide emissions, another important greenhouse gas
vol. 97, no. 18, 29 Aug. 2000, p. 9876. 310 times more powerful than carbon dioxide. 73%
Llanos, Miguel, “‘Alternative’ view offered on of U.S. emissions of nitrous oxide come from animal
battling climate change; NASA scientist: CO2 still a grazing, manure management, and crop growing
factor but other gases are key”, MSNBC News – practices—with half of U.S. crops grown for
Environment, 31 Aug. 2000, http://www.msnbc.com/ livestock feed. Agricultural emissions of nitrous
news/447151.asp. oxide in the U.S. increased 9% from 1990 to 2002.
Gore, Albert, Earth in the Balance, Houghton “Inventory of U.S. Greenhouse Gas Emissions: 1990-
Mifflin Co., 2000, p. 176. 2002,” EPA 430-R-04-003, U.S. Environmental
Hansen, James E., “The Global Warming Debate”, Protection Agency, 15 April 2004, p. ES-16,
NASA Goddard Institute for Space Studies http://www.epa.gov/globalwarming/publications/
Education, http://www.giss.nasa.gov/edu/gwdebate/. emissions.
Hansen and Sato, supra note 11. Estimated climate “Frequent Questions”, Ruminant Livestock, U.S.
forcing of methane from 1850 to 2000 is 0.7 W/m2, Environmental Protection Agency,
while estimated forcing of CFCs, tropospheric ozone, http://www.epa.gov/rlep/faq.html.
and nitrous oxide combined is 0.9 W/m2. 28
“The Role of ‘Other Gases’ in Addressing Climate
“Global Warming Potentials”, supra note 10. Change”, supra note 23.
Atmospheric CO2 concentrations have risen from “Water Quality Conditions in the United States”,
278 parts per million (ppm) in 1750 to 365 ppm in U.S. Environmental Protection Agency, August 2002,
1998. Atmospheric concentrations of methane have http://www.epa.gov/305b/2000report.
increased by 149% since 1750, from .700 ppm to Herein, the term “vegetarian” is used to refer not
1.745 ppm. “Emissions of Greenhouse Gases in the just to a meatless diet, but to one free of animal
United States 2002”, Chapter 1, Energy Information products, i.e. a “vegan” diet. Dairy cows, for
Administration, U.S. Department of Energy, October example, produce even more methane per animal
2003, http://www.eia.doe.gov/oiaf/1605/ggrpt. than beef cattle. Logically, the same concerns extend
Natural sources emit 770 billion metric tons of beyond diet to the consumption of other consumer
CO2, and 239 million metric tons of methane, goods derived from livestock, like wool and leather.
compared to 23.1 billion and 359 million, Because ruminant livestock produce far more
respectively, for anthropogenic sources. “Emissions methane than non-ruminant livestock, reductions in
of Greenhouse Gases in the United States 2002”, agricultural methane can also be achieved by shifting
supra note 20. consumption away from cows and sheep in favor of
Hansen, et al, supra note 5. It is also possible that chickens and pigs. However, the benefits of such
warming may dampen natural sources of methane by shifts are not simple; for example, in the U.S.,
drying out wetlands. manure from pigs produces more than five times as
Animal agriculture is responsible for 32% of global much methane as manure from beef cattle.
methane emissions from human activity, including (“Inventory of U.S. Greenhouse Gas Emissions:
28% from domesticated livestock and 4% from 1990-2002”, p. 181, supra note 17.) Moreover, the
livestock manure. Natural gas is the second largest large scale production of these animals in
source, accounting for 15% of emissions. Kruger, concentrated animal feeding operations (CAFOs) is
Dina, “The Role of ‘Other Gases’ in Addressing associated with numerous other environmental harms
Climate Change”, U.S. Environmental Protection already extensively documented by environmental
Agency, 12 Feb 2004, http://www.iges.or.jp/en/cp/ organizations, making the trade of one environmental
output_all/workshop/usjapan/pdf/06Kruger.pdf. danger for another a Faustian bargain.
“Emissions of methane from livestock”, Climate The U.S. Environmental Protection Agency’s
Change Fact Sheet 32, Information Unit on Climate efforts to address methane from livestock amount to
Change (IUCC), UNEP, 1 May 1993, encouraging changes in feed and increasing the
http://www.unep.ch/iucc/fs032.htm. amount of product (meat, milk, offspring) per animal.
World meat production reached 242 million tons in Even at best such efforts are unlikely to achieve large
2002, from 122 million tons in 1977, and from 44 reductions in emissions per animal, and any such
million tons in 1950. Additionally, per capita meat reductions are easily swamped by increases in the
consumption has more than doubled since 1950, from number of animals raised overall. Methane emissions
17 to 39 kg per person. Vital Signs 2003, Worldwatch from manure can also be captured and used to
Institute, May 2003, p.30-31, produce energy.
http://www.worldwatch.org/pubs/vs/2003. The Hansen, et al, supra note 5.
majority of the meat is consumed by developed Pimentel and Pimentel estimate that the production
countries. Delgado, Christopher et al., Livestock to of animal products requires more than 10 times as
2020: The Next Food Revolution, “Food, Agriculture, much fossil fuel as the production of plant foods,
and the Environment Discussion Paper 28”, averaging 25 kcal of fossil fuel input per kcal of animal
International Food Policy Research Institute, May protein, compared with 2.2 kcal of fossil fuel input per
1999, http://www.ifpri.org/2020/dp/dp28.pdf. kcal of plant protein. Pimentel, David and Marcia
“The Role of ‘Other Gases’ in Addressing Climate Pimentel, “Sustainability of Meat-Based and Plant-
Change”, supra note 23. Methane emissions come Based Diets and the Environment”, American Journal
particularly from ruminant animals, like cows, sheep, of Clinical Nutrition, Vol. 78, No. 3, September 2003,
buffalo, and goats, but also from non-ruminants like pp. 660S-663S. On CO2 see Tidwell, Mike, “Food and
pigs and horses. “Emissions of methane from the Climate Crisis: What You Eat Affects the Sky”,
livestock”, supra note 24. Sierra Club Redwood Chapter Newsletter, Dec./Jan.
Not including methane released from manure, an 2005, http://www.redwood.sierraclub.org/articles/
adult cow produces 80-110 kg of methane a year. December_04/FoodClimateCrisis.html.
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