Scientists have estimated that about 15% of all emissions come from worldwide livestock, mostly reared for consumption of meat or milk. That's 7.1 billion tons of carbon dioxide equivalent.
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One way of cutting emissions would be to reduce this meat consumption. Perhaps a beginning could be made by having a few days on which people do not consume meat, especially beef, because beef contributes over 40% of emissions from all livestock.
Meat consumption has zoomed up from 70 million tons in 1961 to 278 million tons in 2009 - a 300% increase in 50 years. According to FAO, meat consumption is expected to rise to 460 million tons by 2050. All this meat, the bulk of which is beef, is grown in gigantic industrial farms in Europe, US, South America and Australia.
FAO estimates that there were about 1.4 billion cattle and one billion pigs and sheep in the world in 2010.
But what's the connection to climate change? The animals themselves emit an enormous amount of methane which is generated in their digestive system. FAO estimates that in 2013, this process, called enteric fermentation generated 39% of all livestock emissions.
Almost a quarter of the world's arable land is used to grow feed for this livestock, including soya bean and corn. Fertilizers are used profligately for this, contributing to nitrogen oxides emissions, besides the loss of forests to clear land. This contributes another 21% of emissions.
The manure produced by these animals runs into millions of tons and produces 26% of emissions, mostly nitrogen oxides. The remaining 14% are generated from various energy uses for transportation, processing and from land use changes - like deforestation - to provide land for growing feed.
Various scientific studies show that among all meats, beef has the highest carbon emitting potential. An analysis of 27 European Union countries found that a kilogram of beef is the cause of 22.6 kg CO2 emissions compared to 2.5 kg from pork, 1.6 from poultry, and 1.3 kg from milk.
The emissions vary from region to region because of rearing practices. Consumption of one kg beef emits as much greenhouse gases as driving a car 160 kilometers.
Plant cultivation is responsible for much less emissions: as compared to 16 kg CO2 per kg beef in UK, one kg of wheat was found to emit just 0.8 kg CO2. ■