Here is an interesting exchange from the July 2, 2011 issue of New Scientist magazine: Three letters from readers addressing various aspects of the topic. The aim here is not to choose sides or sway opinions, but to illustrate just how deep such issues can be and make the point that 'common sense' is often misleading...
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One suggestion to combat climate change is that we should become vegetarians, as livestock is more environmentally damaging than growing crops. However, if we stopped eating meat, livestock would still live, so is the suggestion correct? Or are we expected to cull any remaining pigs and cows?
Hillary Shaw, Senior lecturer and food research consultant
Harper Adams University College, Newport, Shropshire, UK
World population now stands at almost 7 billion, and is projected to level off at around 10 billion by 2050. The world currently has 17.3 million square kilometres of cultivated land; that area of land could feed 3 billion people eating mainly meat, or 42 billion people eating a strict vegan diet of mainly potatoes. For a more varied vegetarian diet, with vegetables, fruit, eggs and milk, we could feed up to 12 billion people on current world farmland and we could also eat seafood. On the negative side, these figures make no allowance for food waste or losses from disease or other disruptions to the food chain.
Farm animals produce much else besides meat, such as wool, leather, milk, cheese and eggs; so even in a vegetarian world, some animals would be retained, but far fewer. The lifespan of most farm animals is quite short, between 10 and 20 years at the most and often fewer. So without breeding, their population would fall quickly. Farm animals produce carbon dioxide but only as much as was locked up in the grass they ate. They also produce methane, another greenhouse gas, but so do rice paddies and submerged vegetation in reservoirs.
The main benefits of a vegetarian diet with respect to global warming would be a reduction in emissions from the energy used to transport meat from farm to fork:because less land is needed to grow vegetables, more food could be produced locally. However, intensive greenhousing, such as in the Netherlands, can be very energy intensive, especially as consumers insist on having many vegetables available on supermarket shelves all year round, even out of season.
The main environmental benefit from everyone going vegetarian would not be reduced global warming but less pressure on world ecosystems - terrestrial and marine - to feed 10 billion mouths. Indirectly, global warming might be reduced as less rainforest is felled, less energy devoted to food transport and less energy needed for intensive farming methods. On the "downside", we might all be healthier and less obese, so we'd live longer and world population would be increased somewhat.
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Chris Smaje
Frome, Somerset, UK
Few livestock are kept for longer than two years before slaughter for meat, and because we farmers respond readily to the economics of supply and demand, it wouldn't be long before decreasing consumer demand for meat was reflected in smaller numbers of farm animals.
The questioner's statement that "livestock is more environmentally damaging than growing crops" begs many questions. A grass-fed suckler operation for beef, for example, produces less carbon than a similarly sized arable farm. Livestock can be integrated into vegetable-growing systems in order to reduce the amount of climate-damaging tillage and diesel use.
To farm sustainably and minimise machine tillage, farms will probably still need livestock, albeit in far smaller quantities.
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Jan Horton
West Launceston, Tasmania, Australia
The largest proportion of any crop is inedible for humans. All that biomass has to go somewhere, and the easy thing to do is feed it to animals that process it into meat. The sheer volume of low-grade waste is too great to process for biofuel and the cost for other forms of disposal would be massive. If it is not removed, the next crop cycle will not be able to be planted. Rotting plants produce greenhouse gasses too.
Other animals will move in, multiply hugely and deal with the biomass. They will also produce the same greenhouse gases as cattle do now. In Australia this will probably fall to rabbits, kangaroos, camels, wild pigs and buffalo.
As my university lecturer says: "Given the same area of land, you can feed a lot more people on bread and pea soup than you can on steak, but you can do it for a lot longer and with fewer problems if everyone gets bread, pea soup... and some steak." The cattle eat the pea vines and live on the pasture, which is used to rotate the wheat and pea plots. The dung and urine can fertilise the soil and humans get to eat a steak here and there.
This is a complex process without an easy solution. So don't feel guilty eating the odd steak. Just ensure it was grown largely on pasture and crop residues and not transported too far.
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For an in-depth analysis of what would happen if we all stopped eating meat, take a look at "
What's the beef with meat?", New Scientist, 17 July 2010, p 28 - Ed
: the Rise and Fall of Information Empires by Tim Wu is an interesting and highly valuable read. Framed as an inside-looking-out history of the greatest industries of our day -- from AT&T and the American motion picture studios to the major cable and television networks -- the book details just how some of the leading characters in American business centralized control of each of those industries, identifies those seeking to do the same with the internet and provides detailed reasons why we should care.
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