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 fertilizers 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 disastrous global warming. It’s probably 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 fertilizer use by 50% and persuade consumers in the developed world to stop eating so much meat. Davidson concedes it’s a hard sell. "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 fertilizers and manure (粪肥) responsible for climate change. Nitrous oxide (一氧化二氮), released by fertilizers 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 food crops that go directly into the human food chain. Eating less meat would reduce demand for fertilizers as well as reduce the amount of manure produced. Davidson also suggests changes in current farming practice. For example, such as growing winter ground cover crops would help absorb nitrogen (氮) and prevent its release into the atmosphere. In reaching his conclusion, Davidson draws on figures from the Food and Agricultural Organization suggesting the world population will reach 8.9 billion by 2050. Meat consumption is also projected to increase sharply to 89kg per person a year in rich countries. Such a trajectory (发展轨迹) 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. 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 footprint (碳排放量), to chicken or fish. We can infer that one benefit of eating less meat is that it can reduce ______.

A. the planting of food crops
B. the demand for fertilizers
C. the emissions of nitrous oxide
D. the amount of manure produced