Fertilisers used in growing feed crops for cattle produce the most potent of the greenhouse gases causing climate change
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Meat eaters in developed countries will have to eat a lot less meat, cutting consumption by 50%, to avoid the worst consequences of future climate change, new research warns.
The fertilisers used in farming are responsible for a significant share of the warming that causes climate change.
A study published in Environmental Research Letters
warns that drastic changes in food production and at the dinner table are needed by 2050 in order to prevent catastrophic global warming.
It's arguably the most difficult challenge in dealing with climate change: how to reduce emissions from food production while still producing enough to feed a global population projected to reach 9 billion by the middle of this century.
The findings, by Eric Davidson, director of the Woods Hole Research Centre in Massachusetts, say the developed world will have to cut fertiliser use by 50% and persuade consumers in the developed world to stop eating so much meat.
Davidson concedes it's a hard sell. Meat is a regular part of the diet in the developed world. In developing economies, such as China and India, meat consumption has risen along with prosperity.
"I think there are huge challenges in convincing people in the west to reduce portion sizes or the frequency of eating meat. That is part of our culture right now," he said.
Researchers have been paying closer attention in the past few years to the impact of agriculture on climate change, and the parallel problem of growing enough food for an expanding population. Some scientists are at work growing artificial meat
which would avoid the fertilisers and manure responsible for climate change.
Nitrous oxide, released by fertilisers and animal manure, is the most potent of the greenhouse gases that cause climate change. The UN's climate body has called for deep cuts to those emissions.
Growing feed crops, for cattle and pigs, produces more of those emissions than crops that go directly into the human food chain. Eating less meat would reduce demand for fertiliser as well as reduce the amount of manure produced.
Davidson also suggests changes in current farming practice - such as growing winter ground cover crops - would help absorb nitrogen and prevent its release into the atmosphere.
In reaching his conclusion, Davidson draws on figures from the Food and Agricultural Organisation suggesting the world population will reach 8.9 billion by 2050, and that daily per capita calorie intake will also rise to 3130 calories.
Meat consumption is also projected to increase sharply to 89kg per person a year in rich countries and 37kg per person a year in the developing world.
Such a trajectory would put the world on course to more severe consequences of climate change.
Davidson is not suggesting people give up meat entirely. "The solution isn't that everyone needs to become a vegetarian or a vegan. Simply reducing portion sizes and frequency would go a long way," he said. So would switching from beef and pork
, which have a high carbon foot print, to chicken or fish.