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研究报告：人类少吃肉对环境有好处

A new study says one of the best ways to curb¹ greenhouse gas emissions² is to eat less meat. In fact, the study says meat consumption in the developed should be cut by 50 percent per person by 2050.

一份新的研究说，遏制温室气体排放最好的办法之一是少吃肉。事实上，研究说，已开发国家每人的肉类消费量应该在2050年前减少50%。

Meat production and consumption are expected to soar by 2050. That’s because the global population is projected to grow from the current 7 billion to 9 billion. But also, the diets of people in many developing countries are changing. Countries with emerging economies are seeing a sharp rise in protein consumption, especially red meat.

肉类生产和消费将在2050年前上升，这是因为全球人口预计从目前70亿增加到90亿。但同时，许多发展中国家人民的饮食正发生变化。新兴经济体对蛋白质，尤其是红肉的消费急剧上升。

Dr. Eric Davidson said changing how people eat can have a dramatic effect on greenhouse gas emissions. People in developed countries, he said, already eat much more protein than the daily minimum requirement.

艾瑞克.大卫森博士说，改变人们的饮食会对温室气体排放有显著影响。他说，已开发国家人们吃的蛋白质已经远超过每日所需。

“In the developed world there’s considerable room for us to manage our portion sizes and the frequency with which we eat meat. We’re not talking about everybody suddenly needing to become a vegetarian³. Rather it’s kind of reversing the supersize trend and being more mindful of the impacts of the amount of meat and the types of meat, both for the environment and our own health,” he said.

大卫森说：“在已开发国家，我们吃肉的份量和频率还有很大的改变空间。我们不是说每个人要突然变成素食者。而是说，要扭转超大份量的趋势，更注意肉类的份量和种类对环境和自身健康的影响。”

Davidson is the president and senior scientist at the Woods Hole Research Center in Massachusetts.

麻萨诸塞州伍德霍尔研究中心的主席和资深科学家大卫森说：

Meat, manure⁴ and gas

“If there is a growing demand for meat, which of course there is, that is going to end up requiring use of more nitrogen fertilizer and production of more livestock⁵ manure, both of which end up resulting in unintentional releases of various forms of nitrogen to the environment, including nitrates to groundwater and surface water and also greenhouse gases such as nitrous oxide⁶ to the atmosphere,” he said.

“如果对肉的需求增加--确实也有所增加，那么就需要使用更多氮肥和制造更多粪肥，两个都会无意间对环境释放出不同形态的氮，包括向地下水和地表水排放硝酸盐，同时将氧化亚氮等温室气体排到空气中。”

Davidson looked for ways to ease the effects of climate change that would support an aggressive strategy laid out by the Intergovernmental Panel on Climate Change. In particular, the effects of nitrous oxide, described as the third biggest contributor to climate change after carbon dioxide and methane⁷.

大卫森寻找缓解气候变迁影响的方式，来支持政府间气候变迁小组所制定的一份积极策略。他说，特别是氧化亚氮产生的影响，氧化亚氮被形容是二氧化碳和甲烷之外促成气候变迁的第三大因素。

But while nitrous oxide ranks number three in greenhouse gases, it is considered the most potent⁸. It’s much better at absorbing infrared⁹ radiation. In other words, the sun’s energy passes through the Earth’s atmosphere, heats things up and is then released through infrared radiation. But that radiation then hits the greenhouse gases in the atmosphere and goes no further.

虽然氧化亚氮在温室气体中排名第三，但它被认为是最有力的。它对红外幅射的吸收力更强。换句话说，太阳能穿透地球的大气层、加温、然后通过红外幅射释放。但当幅射在气层遇到这个温室气体后就无法再散出去。

Davidson has a simple analogy.

大卫森作了一个类比说：

“It’s sort of the same idea as a parked car. The energy goes through the windshield of a car pretty easily. It’s absorbed on the car seat. Gets the car seat hot. Re-radiates out and it cannot escape the windshield on the way out. This infrared radiation cannot escape the windshield and so the inside of the car heats up. The physics is pretty well understood for climate change. I think we’d probably have better acceptance of it if we called it the parked car effect instead of the greenhouse gas effect,” he said.

“这有点象停着的车。能量能轻易穿透车窗，被车内的座椅吸收，让椅子变热。然后它重新向外散发时却无法穿过车窗，所以车内变热。这个物理学很能解释气候变迁。我想，如果我们称它车子效应而不是温室气体效应会比较容易接受。”

And nitrous oxide stays in the atmosphere a very long time before breaking down. It can take over a hundred years to break down one molecule¹⁰ of the gas. The main sources of nitrous oxide are synthetic¹¹ nitrogen fertilizers and storage and use of livestock manure.

氧化亚氮在分解前会在空气中停留很长一段时间。分解一个气体分子可能花超过一百年。氧化亚氮的主要来源是合成氮肥以及粪肥的储存和使用。

Start now

Davidson says farmers should be given incentives¹² to use fertilizers and manure more judiciously¹³.

大卫森说，应该给农夫诱因让他们更明智地使用肥料和粪肥。

“If we want to meet the most ambitious and optimistic goal of these scenarios¹⁴ of bringing harmful climate change under control, we need to improve the efficiency with which we use fertilizers in agriculture. We need to improve the efficiency of the management of manure. And we also need to consider changes in dietary patterns. And that means hopefully better diets in the developing world and better balanced diets in the developed world,” he said.

大卫森说：“如果我们想要达到控制气候变迁的有野心而乐观的目标，我们要改善农业使用肥料的效率。我们要改善处理粪肥的效率。我们还需要思考改变饮食模式。希望在发展中国家有更好的饮食和已开发国家更均衡的饮食。”

Even if it were possible to turn off all harmful greenhouse gas emissions today, he said climate change would continue.

即使今天有办法消除所有温室气体，他说，气候变迁还是会继续。

“That doesn’t mean that we shouldn’t start the mitigation now because the sooner we start it the more options our children and grandchildren will have in terms of being able to feed themselves and have prosperous lifestyles without environmental degradation,” he said.

大卫森说：“这不代表我们不应该现在就开始减少温室气体，因为我们越快开始，我们的子孙在不破坏环境下养活自己和拥有繁荣生活方面就有越多选择。”

Davidson’s findings appear in IOP Publishing’s Environmental Research Letters.

大卫森的研究刊在英国物理学会出版社《环境研究通讯》。