Animal Agriculture and Global Warming

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Animal Agriculture and Global Warming

By Stephen R. Kaufman, M.D., Christian Vegetarian Association (CVA)
October 2010

If we are serious about attending to what nearly all environmentalists agree is a growing crisis, moving toward a plant-based diet is an essential step.

The Bible describes the Garden of Eden as a place where the environment provided everything that living beings needed. Whether the environment was created to suit our bodies (as a literal reading of the Bible suggests) or that we evolved so that we are well-suited to the environment, one thing should be obvious – our changing the environment is probably not a good idea. Yet that, scientists nearly universally agree, is exactly what is happening. Indeed, global warming might be the leading threat to humanity, and animal agriculture is a leading contributor to the problem.

Many animal advocates cite the remarkable 2006 United Nations Food and Agriculture Report entitled Livestock’s Long Shadow, which attributed 18% of greenhouse gasses to animal agriculture. This is more than all forms of transportation – including cars, trucks, and airplanes – combined. A 2009 article in World Watch concluded that the actual figure was a staggering 51%. How did the article arrive at this figure?

The authors, Robert Goodland and Jeff Anhang, note several significant sources of greenhouse gasses that were either ignored or largely overlooked in the FAO report. For example, a huge amount of land that could sequester a large amount of CO2 in the form of trees and other plant material is prevented from doing so because that land is devoted to growing feed for farmed animals. The authors argue, I think reasonably, that a lost opportunity to ameliorate the problem of rising atmospheric CO2 and other greenhouse gasses should be considered just as important as activities that contribute directly to the problem. In addition, soils contain a huge amount of organic compounds that release CO2 when they are exposed to air by tilling and cultivation and then broken down by aerobic microorganisms.

Goodland and Anhang note that 37% of human-induced methane comes from animals raised for food. Methane is a much more potent greenhouse gas than CO2, but it has a shorter atmospheric half-life – 8 years for methane versus at least 100 years for CO2. When calculating methane contributions to global warming, scientific models have spread out its effect over 100 years, which greatly reduces its actual effect in the near future and increases its effect (according to the models) in 100 years. Goodland and Anhang argue that this is not appropriate, since global warming will have a real short-term effect that will be environmentally and socially disruptive. Further, I think their approach makes more sense, because short-term increases in greenhouse gasses will enhance some of the positive feedback loops of global warming. For example, as temperatures rise, polar ice caps melt, exposing more ocean to sunlight, and oceans absorb about 70% of the sun’s heat, while ice absorbs only about 10% and reflects the rest back into space. Three of the four largest Arctic summer ice melts have been in the last four years. Recent ice melts have averaged over 800,000 square miles more than the 1979-2000 average, a staggering 0.4% of the earth’s surface area. The warmed water further melts sea ice, and there is a good chance that the Arctic summer sea ice will completely melt by 2020.

Goodland and Anhang detail other sources of greenhouse emissions associated with animal agriculture, and their article can be viewed at http://www.worldwatch.org/files/pdf/Livestock%20and%20Climate%20Change.pdf.

There are uncertainties in any projection of climate change, in part because there are both positive and negative feedback loops that are difficult to calculate. Whether or not animal agriculture actually contributes the majority of greenhouse gasses attributable to humans, it is certainly a large fraction. If we are serious about attending to what nearly all environmentalists agree is a growing crisis, moving toward a plant-based diet is an essential step.