human activity. How does farming fit it and,what is the contribution of animal agriculture

人類活動。農業是如何影響，畜牧業的組成

and how are these values calculated?

及這些價值該如何計算？

The consuming public is more and more interested in where their food comes from, what’s the

大眾消費對於他們的食物從何而來越來越有興趣，碳足跡為何

carbon footprint. What’s the carbon footprint, or the what’s

碳足跡為何，或者是

the environmental footprint, of a gallon of milk, or a pound of beef, or a pound of chicken meat?

什麼是環境足跡，一加侖的牛奶，或一磅的牛肉，或一磅的雞肉？

My name is David Schmidt and I’m an agricultural engineer at the University of Minnesota and

我是大衛史密奇，一名明尼蘇達大學的農業工程師和

Regional Coordinator for the national project, Animal Agriculture in a Changing Climate.

研究畜牧業如何改變氣候的國家專案區域協調員

There is a significant amount of miscommunication about the role of agriculture

有很多關於農業對於氣候變遷的錯誤評論

in climate change. Some say that animal agriculture is the largest contributor to greenhouse gas

有些說法畜牧業是產生最多溫室氣體的製造者

emissions while others deny any contribution from animals. The answer lies somewhere in

然而其他人否認動物是製造者來源。這答案在這兩者之中

between. The objective of this video is to provide you with a solid foundation of how

這影片中可以客觀地提供你完整的

emission estimates are calculated and the real contributions of animal agriculture to

排放計算估計和真實的畜牧業排放在

US and global greenhouse gas(GHG) emissions.

美國及全球的溫室效應排放

Carbon is all around us. It is the fourth most abundant chemical element in the universe,

碳總是圍繞著我們。它是宇宙中第四多的化學成分，

behind hydrogen, helium and oxygen. The biggest reservoir of carbon is stored

排在氫，氦和氧氣之後。存放最多碳的地方在

in rocks- approximately 66,000 gigatons with one gigaton is equal to 1 trillion kilograms.

石頭中-大約660兆噸 ，十億噸等於一兆公斤

The second biggest reservoir is the deep ocean, and the third largest reservoir is in fossil

第二大碳存量是在深海裡，第三大碳存量是在化石中

fuels. The atmosphere and the surface ocean are the smallest carbon reservoirs but possibly

大氣層和海洋表面是碳儲放最少的地方但可能

the most important. Carbon is moving between these reservoirs constantly because of a variety

也是最值得關注的。碳在這儲存區間不斷的移動

of chemical and biological processes. This is known as the carbon cycle.

由於不同的化學及生物反應。這就是大家所了解的碳循環

The total amount of carbon that cycles in and out of the atmosphere naturally each year

大氣層中每年碳循環的總排放量為

is about 210 gigatons. The arrows and yellow numbers indicate this movement, or cycling

2100 億頓。箭頭和黃色的數字代活動變遷，或者是碳循環

of carbon. Plants and oceans are referred to as net carbon “sinks” because they

植物和海洋被歸類於淨碳匯

absorb more carbon from the atmosphere than they emit. These carbon emissions occur in

因為他們從大氣層吸收的碳量大於釋放的量。這些碳排放會發生在

the form of plant respiration and chemical exchanges with the ocean.

植物的光合作用和海洋的化學循環

The red numbers indicate the human influence in the cycle, also known as “anthropogenic

紅色的數字代表人類對碳循環的影響，也被稱之為「人為排放」

emissions.” They can be mostly be attributed to the burning of fossil fuels and changes

常被歸類於燃燒石化燃料及開發土地

in land use. Human activities contribute nine gigatons of carbon emissions annually. About

人類活動的碳排放每年可達90億噸

two gigatons of that carbon gets taken up or absorbed by the ocean. Three gigatons of

大約20億噸的碳可以被使用或被海洋吸收。

that carbon gets absorbed by plants through photosynthesis and taken up in plant soil

30億噸的碳可以被植物吸收做光合作用和植物土壤系統使用

system. All this movement results in an annual net increase of about four gigatons of carbon

這些活動會導致每年淨成長40億噸的碳

going into the atmosphere each year.

到大氣層中

As you can see in this diagram, the amount of carbon dioxide in the atmosphere was relatively

你可以看到這些圖表中，大氣層中二氧化碳的量

stable for hundreds of thousands of years, at an average of around 230 parts per million.

在這幾千年間是非常穩定的，約平均百萬分之230

Then about 100 years ago, the CO2 concentration in the atmosphere began climbing to where

大約100年前，大氣層中二氧化碳的濃度攀升到現在的水位

it is right now, about 400 parts per million.

大約百萬分之400

This animated diagram more dramatically illustrates the rise in carbon dioxide levels in the earth’s

這個動態圖表更戲劇化的展現二氧化碳在大氣層中

atmosphere in more recent years, since 1979. The numbers on the left and right indicate

自1979年上升的程度。左側及右側的數字代表

the CO2 concentration in parts per million. Again this indicates the current CO2 level

二氧化碳濃度比例 以百萬分為單位。再次說明現在二氧化碳的濃度

reaching up to and even beyond 400 parts per million.

已經觸及或甚至超越百萬分之400

While we do not intend to focus on all of the greenhouse gases in this lesson, it is

我們並沒有要聚焦所有溫室氣體，

important to note that carbon dioxide is not the only greenhouse gas. The most common greenhouse

重點是了解到二氧化碳並不是唯一的溫室氣體。最常見的溫室氣體

gas is water vapor, followed by carbon dioxide , methane , nitrous oxide and fluorinated

是水蒸氣，緊接在二氧化碳之後，甲烷，一氧化二氮和氟化氣體

gases. Excluding water vapor, the combined sources of carbon dioxide, primarily from

除了水蒸氣，二氧化碳的組成來源主要是從

fossil fuel use and land use change, make up about 77% of the global greenhouse gases.

化石燃料及土地開發，產生約77%的全球溫室氣體

Because these other gases trap different amounts of energy per molecule of gas, scientists

因為這些氣體是由不同的能量分子組成，

have normalized the data into something called Carbon Dioxide Equivalents, or CO2 equivalents.

科學家把這些數據標準化為二氧化碳當量 (CO2e)

This “equivalent” refers to the equivalent heating potential of the gas. This is also

「當量」是以潛在熱能氣體的比例為依據

known as radiative forcing or global warming potential. For instance, a single molecule

這也被稱之為輻射強迫或全球暖化潛勢。舉例來說，

of methane will trap approximately 25 times the amount of energy as will a single molecule

一個分子的甲烷大約等於一分子的二氧化碳的25倍

of carbon dioxide. So methane has a CO2 equivalent of 25. Nitrous Oxide has a CO2 equivalent

所以甲烷的二氧化碳當量是25。氧化亞氮的二氧化碳當量是298

of 298. This use of CO2 equivalents allows us to evaluate the impact of the gases on

使用二氧化碳當量可以讓我們去估計氣體影響環境的程度

the environment - not just the amount of these gasses in the atmosphere.

不只是衡量大氣層中氣體的含量

Anthropogenic greenhouse gases are emitted by many sources and from every country. Together

人為的溫室氣體是來自每個國家不同的排放來源

these nations contribute a world total of 45 thousand million metric tons of CO2 Equivalents.

這些國家一共產生4.5億噸二氧化碳當量

This graph shows percentages of greenhouse gas emissions by country in 2012. The United

這圖表為2012各國家溫室氣體排放的百分比

States is currently the second highest emitter of these gases, contributing about 15% of

美國為現在第二高排放量的國家，大約占全世界排放的15%

the world total. The highest emitting country is China. However, this same information can

最大的排放量國為中國。然而，相同的資訊

be evaluated based on emissions per capita. This breakdown shows the US at about 19 tons

可以用人均排放量進行評估。結果顯示美國每年每人約19噸二氧化碳當量

CO2e per year per person vs China at 7.5 tons CO2e per year per person.

而中國每年每人約7.5噸二氧化碳當量

Taking a closer look at the sources of greenhouse gas emissions in the United States alone by

更近一點觀察美國經濟部分的溫室氣體排放

economic sector, we see that agriculture contributes 9 percent of total emissions in

我們看到農業占9%的總排放量

the US. Total emissions in the US add up to approximately 6,673 million metric tons of

美國總排放量加起來大約667.3萬噸

CO2 Equivalents. Agriculture’s 9% represents about 515 Million Metric Tons of that amount.

二氧化碳當量。農業的9%大約代表51.5萬噸

Looking at the agricultural sector itself, we can see that agricultural soil management

單看農業部份，我們看到農業土壤管理

is the biggest source, it accounts for about 50% of total agricultural emissions. This

是最大的主因，大約占50%的總農業排放

is followed by enteric fermentation at about 32% and manure management at 15%.

再來是腸道發酵32%和糞便管理15%

Now looking at the type of gases emitted, about 55% of the agricultural emissions are

現在來看看排放型態，大約55%的農業排放是從

from nitrous oxide, which is produced naturally through the the microbial process of nitrification

一氧化氮，其通過土壤中礦物氮的硝化

and denitrification of mineral nitrogen in the soil. The remaining 45% is from enteric

和反硝化的微生物過程自然產生。剩餘45%是從

methane or from methane formed during the microbial breakdown of manure. Note that these

腸道發酵或在糞便微生物分解期間形成的甲烷。

emissions are only the direct emissions of greenhouse gases occurring on the farm. Other

這排放是在農場上直接排放溫室氣體

emissions that would occur off farm - like emissions from fertilizer production or electricity

其他不是在農場上排放的 - 像施肥的排放或是電力使用

used on the farm are not included in these numbers.

都沒有包含在這些數字裡

We can also look more closely at emissions by animal species. In this chart you can

我們也可以深入研究動物的排放量。在這張圖中

see the comparisons between beef cattle, dairy cattle, swine, poultry and all other livestock.

你可以看到肉牛、乳牛、豬、家禽和其他家禽類的比較

These differences are primarily a function of total animal numbers and the contribution

這些差異主要是不同的動物數量和

of enteric fermentation. Again these are direct emissions for animal production and do not

腸道發酵的程度。而這些動物產品的直接排放並沒有

include emissions from the production of things like animal feed.

包含像動物飼料的排放

Overall if you look at all animals in the united states for example – the beef sector

總體來說如果拿美國的動物來舉例-牛肉

would have the greatest impact on carbon footprint of this nation but that’s only because there

對美國影響碳足跡最大的唯一原因是

are so much more beef animals than dairy animals. We have 90 million beef animals and 9 million

有太多的肉牛相較於乳牛。我們有9000萬頭的肉牛與900萬頭的

dairy animals, so 10 times more beef animals.

乳牛 ，是10倍的肉牛

However, a better way to think about greenhouse gas emissions is in terms of emissions per

然而，一種更好的方式去思考溫室氣體排放是根據

unit of production. We can look at kilograms of CO2 equivalents per kilogram of product

每單位生產的排放量。我們可以用每公斤為單位的二氧化碳當量

produced or product consumed. This evaluation includes not only direct emissions from the

的製成或產品消耗為單位。這估計方式不只包含農場直接排放

farm, but also the emissions that occur after the products leave the farm. We will discuss

也包含產品離開農場後的排放

this further a little later in the video.This graph compares the greenhouse gas emissions

我們會晚點會再進行討論。這圖表比較了幾種產品以公斤為單位

of several products on per kilogram basis. Of all the products, lamb is the highest emitter

的溫室氣體排放。在所有產品中，羊是每公斤排放量最高的

per kilogram of product consumed, and beef is the second highest emitter at 27 kilograms

產品，而牛肉是第二高排放量的產品為27公斤

of CO2 equivalents per kilogram of beef consumed. Dairy is much lower in emissions, with 1.9

二氧化碳當量。乳製品是排放量最少的

kilograms of CO2 equivalents per kilogram of milk consumed.

1.9公斤的二氧化碳當量

Before getting further into attributing emissions to different sectors of animal agriculture

再進一步將不同種類的排放歸於畜牧業

or to different sources on the farm, we’ll look at the system used to measure and calculate

或不同的農場來源前，我們來看看用來測量和計算排放的系統

these emissions. There is a way to quantify greenhouse gases.

有一種可以來量化溫室氣體的方式

This quantification method is called LCA, life cycle assessment. It has been done for

這個測量方法稱之為生命周期評估(LCA)

many years and it has been done by many different groups using different methodologies.

這已行之有年而且被許多的團體用不同的測量方法實驗

The Life Cycle Assessment, or LCA, is an accounting method that tracks all of the greenhouse gas

生命週期評估(LCA)，是一種會計準則去記錄溫室氣體

emissions produced by a given process, product or system. Often this is called a ‘cradle

從生產過程、產品或系統化的排放程度。亦被稱之為

to grave’ analysis, because it encompasses all of the emissions in the life cycle of

「搖籃到墳墓」分析，因為它包含所有排放的生命週期

the process, product or system being analyzed. This includes anything from the extraction

生產過程、產品或系統化的排放程度進行分析。這包含原物料的萃取

of raw materials to the final disposal of the end product.

到完成品變成廢棄物

Animal scientists, engineers and others can further describe the scope and mission of

動物科學家、工程師及其他學者進一步認為

the LCA as it relates to animal agriculture.

生命週期評估的範圍和任務和畜牧業有關

Basically, the life cycle assessment looks at the entire life cycle associated with a

基本上，生命週期評估是針對一個產品的生命週期

product. Let’s say if McDonalds or Walmart or some other chain were to ask me what’s

如果麥當勞、沃爾瑪或其他的連鎖店被詢問

the carbon footprint or what’s the environmental footprint of a gallon of milk or a pound of

該公司的碳足跡為何或一加侖牛奶或一磅牛肉或一磅雞肉的環境足跡為何

beef or a pound of chicken meat produced by your company.

或一磅雞肉的環境足跡為何

Most producers would have no idea – but a life cycle assessment allows you to do just

很多製造者可能沒有概念 - 但生命週期評估可以給你解答

that.

It allows you to look at the entire life cycle impact of that product. For example, the carbon

這評估可以讓你了解生命週期對環境的影響。舉例來說，

footprint of a gallon of milk includes not just enteric gases that come out the front

一加侖牛奶的碳足跡不只包含牛的腸道氣體排放

end of the cow or methane or other gases that come off the manure, it includes everything

或甲烷或其他堆肥氣體，這包含了所有東西

– the herbicides and other chemicals applied to crops, the crops themselves, the soils

- 除草劑何其他化學藥劑噴灑在穀物上，穀物本身

where the crops are grown, the animals, whether it is enteric gases or manure gases, It includes

及穀物生長的土壤，動物們，不管是不是腸道氣體或堆肥氣體

the cooling of the product, the transport of product and so on. Everything from cradle

這包含產品的冷卻，產品運送等等。每個產品從搖籃

to grave of this product. The true life cycle of this product.

到墳墓的過程。這才是真的產品的生命週期

Life Cycle Assessment is a systematic approach for primarily accounting for environmental

產品生命週期是系統化的方法去評估對環境的影響

impacts. It is a systems scale analysis of any product or service really. In the dairy

對任何產品是系統規模的分析。在乳製品產業

industry. What it means is to divide the system into supply chain stages, typically. In each

基本上它系統化的分析分成不同階段的供應鏈

of those stages we would have what we call unit processes that have material and energy

在每個階段中，我們稱之為每單位的能源流和物質流

flows, inputs and outputs from other unit processes as well as, inputs or outputs from

每單位從其他輸入或輸出和其他環境的輸入或輸出

nature. So emission to the soil, water, or air. And the process of LCA looks from cradle

像土壤、水或空氣的排放。所以生命週期評估的過程就像從搖籃到墳墓的

to grave.

過程

Dr. Thoma’s analysis in 2013 of greenhouse gas emissions from the production of milk

湯瑪士博士在2013年分析美國製造的奶製品溫室氣體排放

in the United States looked at the entire life cycle of the milk supply chain, starting

對整個牛奶供應鏈的生命週期

with the production of fertilizer to grow feed for cows through the consumption of milk

從製造給牛吃的肥料到牛奶消耗

and disposal of milk packaging.

及丟棄牛奶包裝盒

So if we are talking about just the dairy farm so that would be what we might consider

所以如果我們只討論乳製品農場的話　我們需要考慮的是

a gate to gate analysis and we would be interested in what happens just on the farm – that

階段對階段的分析 我們可能會想了解農場所發生的事情 -

would not be considered a full life cycle assessment. So, when we did the carbon footprint

那這樣就不會是完整的生命週期評估。所以，當我們做牛奶的碳足跡

for milk, we literally had to account for the coal, the transportation of the coal,

我們必須要把煤炭算進去，煤炭的運輸，

the construction of the power plant, the losses in the transmission lines to run the refrigeration

發電廠的建置，發冷機的傳輸電線運送損失

units at the retail. So all of that is accounted for.

零售的數量。以上這些都必須考量進去

This table from Thoma’s LCA shows the breakdown of greenhouse gas emissions across the milk

這是從湯瑪士生命週期評估的表格 顯示了乳製品供應鏈溫室氣體

production supply chain. The colors represent the four different types of gas emitted by

排放的分類。這些顏色代表四種不同氣體排放

each stage in the cycle, from feeding the cows, enteric fermentation, manure management

在循環中的每個階段，從乳牛的餵食，腸道發酵，糞便管理

... all the way through the consumption of milk and disposal of packaging. The pie chart

....一直延續到牛奶消耗及包裝丟棄。圓餅圖

further illustrates the percentage of each activity’s contribution to milk’s carbon

更深入說明牛奶碳足跡的百分比在每個製造活動中

footprint.

Thoma’s analysis found that the CO2 equivalents produced by each kilogram of milk consumed

湯瑪士的分析發現每公斤牛奶消耗的二氧化碳當量

ranged from 1.77 to 2.4. This is about 17.6 pounds of CO2 equivalents per gallon of milk

範圍在1.77到2.4。這大約是17.6磅的二氧化碳當量對於每加侖牛奶的消耗

consumed. 72 percent of those emissions occurred before

72%的排放會發生

the milk left the farm gate. So from the extraction of coal, say, for the

在牛奶離開農場前。所以從煤炭的萃取，

electricity that may be used anywhere in the supply chain all the way to the emissions

可被使用在各供應鏈的電力排放

associated with wastewater treatment for wasted milk that goes down the drain or the plastic

一直到廢棄牛奶沿著排水管流至廢水處理或塑膠容器

container that ends up in the landfill and may generate methane. So all of those emissions

最終到掩埋場並產生甲烷。所以對這些排放

across the entire supply chain are, we attempted to account for – tally them up then say

遍佈整個供應鏈，我們試圖要說明 - 這些過程

this is the impact.

就是對溫室氣體的影響

Thoma applied the same system to an analysis of greenhouse gas emissions from pork production.

湯瑪士用了相同的系統去分析豬肉製造的溫室氣體排放

This study took into account all of the activities in the pork supply chain that contribute to

這調查把所有豬肉供應鏈的所有活動

emissions, from electricity and fuel to manure and waste, across all stages of production,

會導致排放，從電力和燃料去到糞便和廢棄物，遍及所有階段的製造過程，

from the sow barn to the consumption of the pork products produced.

從豬糧倉到豬肉的生產製造

The LCA showed CO2 equivalents at an average of 8.8 to 11.6 kilograms of CO2 equivalents

生產週期評估顯示豬肉產生平均每公斤8.8到11.6公斤二氧化碳當量

per kilogram of pork, from production to consumption. This can also be calculated as 2.2 to 2.9

從生產到消耗。這也可以被計算為2.2到2.9

pounds of CO2 equivalents per 4 ounce serving of pork. Approximately 60% of the emissions

磅二氧化碳當量對四盎司豬肉。大約60%的排放

occurred before the product left the farm gate.

發生在產品離開農場前

While the LCA is widely accepted as the most useful and accurate tool for estimating a

當生命週期評估被廣為使用在許多有用和常見工具去估計

farm operation’s environmental impact, there is some interest in learning about farm specific

農場經營對環境的影響，還是有些特定變數會影響

variables that might affect the results. Do differences in farm size, manure handling,

農場的結果。就像農場的大小，糞便處理，

farm practices and technologies, soil conditions, regional climate systems and other farm factors

農場的訓練及科技發展，土壤管理，地區氣候系統和其他農場因素

impact the emissions.

影響排放

When we looked at this in various ways. . . . what wasn’t clear was – oh small farms are

當我們用不同方式來看....不明瞭的是-小農場

not as good as big farms. We saw small farms that were down in the 0.8 0.9 range. We saw

並沒有大農場來的好。我們看到小農場大約在0.8 0.9這區間。我們看

large farms that were in the 1.7 1.8. Our conclusion from that was – it is not what

大農場在1.7 1.8這區間。我們得出個結論是 -

you are managing but how you are managing it so the implementation of best or beneficial

並不是你怎麼管理農場而是你如何去運用並實行最好或是最有用的

management practices and care of the animals, care in the ration formulation, all of these

管理訓練和照護動物，制訂定量管理，這些東西

things contribute to the better performing farms.

都會讓農場表現得更好

Dr. Thoma’s LCA for pork production found some effect from manure management. Farms

湯瑪士博士的豬肉製造生命週期評估發現有些影響是來自於糞便管理

using anaerobic lagoons had slightly higher emissions than those using deep pit systems.

農場用潟湖會有較高的排放相較於深坑管理系統

As noted in the Thoma report, a full LCA encompasses many variables, and with each variable there

而湯瑪士報告中提到，完整的生命週期評估包含很多變數，而每種變數

are some assumptions to be made. How was the electricity used on the farm produced? Was

都有不同的假設狀況。電力在農場的生產過程中是如何被使用?

it coal based or nuclear? Was the corn grown for feed irrigated? If so, what energy source

是用煤炭或核能? 是用玉米飼料去餵食? 如果是的話，幫浦的動力來源是什麼?

powered the pumps? What was the animal diet? How many piglets per sow? How far away is

動物有吃嗎? 一隻母豬生有多少隻小豬? 屠宰場距離有多遠?

the slaughter plant? the consumer market? Was the meat cooked on a gas stove or electric

那消費市集呢? 肉是用瓦斯爐或是電磁爐烹煮?