雖然特朗普政府準備退出巴黎氣候變化協定，但美國很多地方的市長和州長仍然在制定本地的氣候目標，抗議游行不斷出現，社交媒體也群情激奮。可現實是，對抗氣候變化主要是個人的責任，每個人都可以通過調整日常生活細節，輕松高效地保護地球環境。

攝入蛋白質的方式就是個例子。全球有超過800億為食用而養殖的陸生動物。每提供一磅（約合0.45公斤）肉可能就要進食超過15磅飼料。這意味著，畜牧動物提供的食物量遠少于消耗的資源。智庫世界資源研究所的一份報告發現，即便是轉化效率最高的肉類來源，也只能將飼料能源中約11%轉化為人類食物。

為了飼養動物，越來越多天然林地變為農業用地，亞馬遜雨林等森林被焚燒和大片砍伐騰出場地。據聯合國統計，今天地球上整整三成陸地都用于生產肉類、乳制品和禽蛋。聯合國報告還提到，畜牧對全球氣候變化的影響甚至超過了交通運輸業。沒錯，工廠養殖動物對氣候變化的影響超過全球汽車、卡車、火車、飛機和輪船影響的總和。

以上統計結果還沒包括海鮮，其實漏掉了一大塊。數據顯示，1999年到2007年，每年人類從海洋捕獲9700億到2.74萬億條魚，漁船消耗著大量礦石燃料，將各種魚捕撈上岸。也就是說如果將陸海來源綜合起來，我們食物中的動物蛋白產生碳排放量比通常媒體報道中的數字高得多。

動物蛋白生產系統還非常耗水。非營利基金會水足跡網絡的數據顯示，每生產一塊牛排就要消耗2000多加侖（一加侖約合3.79升——譯者注）水，生產一杯牛奶則要消耗800多加侖水，生產約一磅雞肉需要將近600加侖水，一個雞蛋需要約400加侖水。

但人類還是需要蛋白質的，養殖、加工和運輸任何一種食物都要消耗資源。假如我們多食用植物蛋白質，替代大量動物蛋白質，會對氣候變化有什么影響？

據美國環境保護基金報道，美國人每周只要有一餐用植物蛋白質替代雞肉，減少的二氧化碳就超過50萬輛汽車的排放量。

國際期刊《氣候變化》刊發的一篇研究確認，總體而言，“動物來源的食物會比植物來源食物排放更多溫室氣體。”該研究報告的結論是，減少攝入肉類可以降低溫室氣體排放。

的確，為了遏制氣候變化，我們要多吃植物來源的食物，少吃動物來源的食物。幸運的是，自由市場能幫上忙。食品企業正在大量推出看似肉類卻不含肉的食物。

仿肉類雞肉和漢堡正在博得大眾喜愛，其味道和口感都和真正的肉類別無二致。在遍布全美的日用雜貨店，你甚至可以買到不含魚類的海鮮，上面涂著蔬菜風味的塔塔醬。事實上，仿肉類素食行業正迅猛發展：到2020年，植物仿制的肉類產值預計將達到52億美元，商業市場研究機構Market Research Future的最新數據顯示，植物加工奶酪的產值很快會達到35億美元。在美國，目前市面上超過10%的液體奶不含乳制品（如杏仁露和豆奶）。2015年到2020年間牛奶的銷量預計會下降18%。

目前已經可以選用一些純植物來源的食品，協助抑制氣候變化。我們可以用鷹嘴豆替代雞肉沙拉里的雞肉，可以試試黑豆漢堡。要是想讓素食三明治有類似熏肉的口感和風味，我們可以用煎炒過的意大利波托貝洛大蘑菇替代火雞肉。替代肉類的選擇數不勝數，就看有沒有想象力。

隨著市場供應增加，想買植物來源的食品也越來越容易，“無肉星期一”之類活動應運而生也就不足為怪了。一些倡導素食的活動也聲勢日隆，比如知名美食評論家、暢銷書作者馬克·彼特曼發起的VB6（每晚6點以前全素食）。環保意識增強的消費者在遵循三R飲食原則——“減少”攝入動物食品，用植物食品取代，選擇按照更高動物福利標準生產的肉食。他們用各種方式讓世界變得更美好。而且新理念正成為主流。

很明顯，每個人都可以告訴全世界，我們并不需要等待美國政府參與氣候變化之戰，完全可以從家人、朋友和鄰里做起。作為個人，我們也可以挺身而出，直面氣候變化的挑戰，通過調整自身飲食習慣，讓世界更清潔。(財富中文網）?

譯者：Pessy

審稿：夏林

馬修·普雷斯科特是非營利組織美國人道協會食品政策的高級主管，他寫的《食物是解決之道：吃什么能拯救世界》將于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.