改变饮食 我们可以拯救地球

虽然特朗普政府准备退出巴黎气候变化协定，但美国很多地方的市长和州长仍然在制定本地的气候目标，抗议游行不断出现，社交媒体也群情激奋。可现实是，对抗气候变化主要是个人的责任，每个人都可以通过调整日常生活细节，轻松高效地保护地球环境。

摄入蛋白质的方式就是个例子。全球有超过800亿为食用而养殖的陆生动物。每提供一磅（约合0.45公斤）肉可能就要进食超过15磅饲料。这意味着，畜牧动物提供的食物量远少于消耗的资源。智库世界资源研究所的一份报告发现，即便是转化效率最高的肉类来源，也只能将饲料能源中约11%转化为人类食物。

为了饲养动物，越来越多天然林地变为农业用地，亚马逊雨林等森林被焚烧和大片砍伐腾出场地。据联合国统计，今天地球上整整三成陆地都用于生产肉类、乳制品和禽蛋。联合国报告还提到，畜牧对全球气候变化的影响甚至超过了交通运输业。没错，工厂养殖动物对气候变化的影响超过全球汽车、卡车、火车、飞机和轮船影响的总和。

以上统计结果还没包括海鲜，其实漏掉了一大块。数据显示，1999年到2007年，每年人类从海洋捕获9700亿到2.74万亿条鱼，渔船消耗着大量矿石燃料，将各种鱼捕捞上岸。也就是说如果将陆海来源综合起来，我们食物中的动物蛋白产生碳排放量比通常媒体报道中的数字高得多。

动物蛋白生产系统还非常耗水。非营利基金会水足迹网络的数据显示，每生产一块牛排就要消耗2000多加仑（一加仑约合3.79升——译者注）水，生产一杯牛奶则要消耗800多加仑水，生产约一磅鸡肉需要将近600加仑水，一个鸡蛋需要约400加仑水。

但人类还是需要蛋白质的，养殖、加工和运输任何一种食物都要消耗资源。假如我们多食用植物蛋白质，替代大量动物蛋白质，会对气候变化有什么影响？

据美国环境保护基金报道，美国人每周只要有一餐用植物蛋白质替代鸡肉，减少的二氧化碳就超过50万辆汽车的排放量。

国际期刊《气候变化》刊发的一篇研究确认，总体而言，“动物来源的食物会比植物来源食物排放更多温室气体。”该研究报告的结论是，减少摄入肉类可以降低温室气体排放。

的确，为了遏制气候变化，我们要多吃植物来源的食物，少吃动物来源的食物。幸运的是，自由市场能帮上忙。食品企业正在大量推出看似肉类却不含肉的食物。

仿肉类鸡肉和汉堡正在博得大众喜爱，其味道和口感都和真正的肉类别无二致。在遍布全美的日用杂货店，你甚至可以买到不含鱼类的海鲜，上面涂着蔬菜风味的塔塔酱。事实上，仿肉类素食行业正迅猛发展：到2020年，植物仿制的肉类产值预计将达到52亿美元，商业市场研究机构Market Research Future的最新数据显示，植物加工奶酪的产值很快会达到35亿美元。在美国，目前市面上超过10%的液体奶不含乳制品（如杏仁露和豆奶）。2015年到2020年间牛奶的销量预计会下降18%。

目前已经可以选用一些纯植物来源的食品，协助抑制气候变化。我们可以用鹰嘴豆替代鸡肉沙拉里的鸡肉，可以试试黑豆汉堡。要是想让素食三明治有类似熏肉的口感和风味，我们可以用煎炒过的意大利波托贝洛大蘑菇替代火鸡肉。替代肉类的选择数不胜数，就看有没有想象力。

随着市场供应增加，想买植物来源的食品也越来越容易，“无肉星期一”之类活动应运而生也就不足为怪了。一些倡导素食的活动也声势日隆，比如知名美食评论家、畅销书作者马克·彼特曼发起的VB6（每晚6点以前全素食）。环保意识增强的消费者在遵循三R饮食原则——“减少”摄入动物食品，用植物食品取代，选择按照更高动物福利标准生产的肉食。他们用各种方式让世界变得更美好。而且新理念正成为主流。

很明显，每个人都可以告诉全世界，我们并不需要等待美国政府参与气候变化之战，完全可以从家人、朋友和邻里做起。作为个人，我们也可以挺身而出，直面气候变化的挑战，通过调整自身饮食习惯，让世界更清洁。(财富中文网） 

译者：Pessy

审稿：夏林

马修·普雷斯科特是非营利组织美国人道协会食品政策的高级主管，他写的《食物是解决之道：吃什么能拯救世界》将于2018年春季面世。

With America preparing to exit the Paris climate accord, mayors and governors are setting their own climate goals, protests are erupting, and social media is all atwitter. But the reality is that combating climate change is largely a matter of personal responsibility—and one of the easiest and best steps we can take concerns what we put on our plates.

Take protein, for example. Worldwide, over 80 billion land animals are farmed for food. To produce just a single pound of meat, those animals may each eat upwards of 15 pounds of feed—meaning mass meat production funnels far more resources through animals than it gets out of them. One report from the World Resources Institute found that even the most efficient sources of meat convert only around 11% of feed energy into human food.

And to grow all that animal feed, the industry is constantly converting more native lands to agricultural operations—burning and clear-cutting the Amazon and other forests to make way for feed fields. Today, a whopping 30% of Earth's landmass goes to meat, dairy, and egg production, according to the United Nations. As the UN also reports, livestock production causes “an even larger contribution" to climate change "than the transportation sector worldwide.” That’s right: Factory farmed animals contribute more to climate change than all the world’s cars, trucks, trains, planes, and ships combined.

And those calculations don’t even include seafood—which is a huge omission. According to data from 1999 to 2007, between 0.97 and 2.74 trillion fish were taken from the oceans annually, dredged up in nets many miles long that are pulled by ships burning huge quantities of fossil fuels. This means that emissions from animal proteins in our diet—land and sea combined—are substantially higher than the already very high numbers commonly reported.

It’s also a thirsty system: According to Water Footprint Network data, it takes over 2,000 gallons of water to produce a single steak and over 800 gallons to produce a single glass of milk. Nearly 600 gallons are used to produce just one pound of chicken meat, and nearly 400 gallons go into just one egg.

But we all need protein, and growing, processing, and transporting food of any kind requires resources. So what would the impact on climate change be if we simply processed more plant products into protein-packed foods, rather than funneling so many through animals first?

The Environmental Defense Fund reports that if each American replaced chicken with plant-based foods at just one meal per week, the carbon dioxide savings would be the same as taking more than half a million cars off U.S. roads.

On the whole, “the production of animal-based foods is associated with higher greenhouse gas emissions than plant-based foods,” confirms a study published in the journal Climate Change. Thus, concludes the report, reducing our meat consumption would lead to lower greenhouse gas emissions.

Indeed, in order to curb climate change, we must eat more plant-based foods and fewer animal-based foods. And fortunately, the free market is helping us do exactly that. Companies are now sprouting up left and right to produce meat-like but meat-free foods.

Meat-free chicken and burgers that hold nearly the same taste and texture as their meaty counterparts are gaining in popularity. At mainstream grocery stores nationwide, one can even buy fish-free seafood and vegan tartar sauce to top it with. Indeed, the sector is growing rapidly: The plant-based meat sector is expected to reach $5.2 billion by 2020, and new data from Market Research Future shows the plant-based cheese sector will reach $3.5 billion soon after. As well, non-dairy milks (like almond and soy) now account for more than 10% of all fluid milk sales in the U.S., with sales of cow’s milk projected to drop 18% between 2015 and 2020.

There are also whole, plant-based foods readily available to help us each curb climate change. We can replace the chicken in our chicken salad with chickpeas. We can try black bean burgers, and fill our sandwiches with sautéed Portobello mushrooms instead of turkey for a meaty, smoky texture and flavor. The list of options is only as limited as our creativity in the kitchen.

With the marketplace making it easier to eat more plant-based foods, it’s no surprise that movements like “Meatless Monday” have taken off. Programs like bestselling author Mark Bittman’s “VB6” (eating vegan before 6 p.m.) are growing. Conscious consumers are making the world a better place by following the three “R”s of eating: “reducing” and “replacing” consumption of animal products and “refining” our diets by choosing products from sources that adhere to higher animal welfare standards. These types of ideas have become mainstream.

We clearly each have the power to show the world—starting with our families, friends, and neighbors—that we needn’t wait for Washington in the war on the climate change. As individuals, each of us can rise to meet climate change’s challenges by adjusting our own habits to create a cleaner world.

Matthew Prescott is senior director of food policy for The Humane Society of the United States and author of Food is the Solution: What to Eat to Save the World, forthcoming in spring 2018.