January 24, 2009
This is the inconvenient truth that most people don’t want to touch. The reality is that the world’s livestock industry is responsible for up to 18% of the total problem – more than all the world’s transport. “How can this be?” you might ask. To understand, we have to remember there are several greenhouse gases that trap heat in the atmosphere – not just CO2 from fossil fuels. There is also methane (CH4) that traps 25 times more heat per molecule than CO2 over 100 years, and nitrous oxide (N2O) that traps 298 times more. The UN report Livestock’s Long Shadow teases apart why cattle, sheep and pigs are such a large cause of global warming.
First, some background data: there are 6.6 billion humans on Earth – and 20-30 billion livestock animals. 30% of the Earth’s land is used for livestock, and of the arable land that is suitable for farming, 33% is used to grow feed for livestock. It takes 2-10 kg of feed to produce 1 kg of meat. The problem starts with CO2 from the burning forests to grow feed for livestock. 70% of previously forested land in the Amazon is used for livestock pasture; the rest for feed crops, mostly soy (95% of global soy production is for animals). The burning releases 2.4 billion tonnes of CO2 a year.
Then there is the fact that cows burp methane, as do buffaloes, sheep, and goats. 33% of the world’s methane comes from livestock, adding 2.2 billion tonnes when measured as CO2e.
Finally, when nitrogen fertilizer is applied to the land much of it escapes as nitrous oxide; it is also produced by animal manure. With a GWP of 298, this adds 2.2 billion tonnes of CO2e. The total comes to 7.1 billion tonnes, or 18% of the 40 billion tonnes of CO2e humans produce each year. A Japanese study suggested that each kilogram of beef is responsible for 36.4 kg of CO2e. Organic beef raised on grass produces 40% less CO2e. It is also healthier, since it contains good Omega 3 fatty acids, instead of harmful Omega 6 fatty acids that arise when cattle eat grain.
The solution is to adopt a far more vegetarian and vegan diet, and to reduce our consumption of beef, pork, lamb, and dairy. We need public education about the impact of livestock; carbon taxes that include methane and nitrous oxide; and an end to all government support for the livestock industry.
There’s an important footnote. Methane’s natural life in the atmosphere is 12 years. Its global warming potential (GWP) of 25 x CO2 is measured over 100 years purely as a statistical convenience. Methane’s GWP over 12 years is around 100 – four times more than we are allowing for. Over 12 years, which is what matters if we are to avoid the global tipping points, livestock’s methane produces 8.8 GT of CO2e, and its responsibility for global warming rises to 24% of the overall problem. Our hamburgers are far more harmful than our cars – which are also a big problem that we have to address.
First published in EcoNews: A monthly newsletter funded by your donations that dreams of a world blessed by the harmony of nature, the pleasures of community, and the joys of personal fulfillment, guided and protected by our active citizenship.