A climate change solution that's right under our feet | Asmeret Asefaw Berhe

譯者: Regina Chu 審譯者: Marssi Draw

So one of the most important solutions

有個很重要的方法

to the global challenge posed by climate change

能解決全球因氣候暖化 而構成的挑戰，

lies right under our foot every day.

天天都被我們踩在腳下，

It's soil.

那就是「土壤」。

Soil's just the thin veil that covers the surface of land,

土壤只是覆蓋地表那薄薄的一層，

but it has the power to shape our planet's destiny.

卻有力量改變地球的命運。

See, a six-foot or so of soil,

你看，六英尺左右的土壤，

loose soil material that covers the earth's surface,

鬆鬆的土壤物質覆蓋著地表，

represents the difference between life and lifelessness in the earth system,

區別出地球系統中的生命和無生命，

and it can also help us combat climate change

還可以幫助我們與氣候變遷戰鬥，

if we can only stop treating it like dirt.

只要我們不視之如塵土。

(Laughter)

（笑聲）

Climate change is happening,

氣候正在變遷，

the earth's atmosphere is warming,

地球的大氣也在變暖，

because of the increasing amount of greenhouse gases

因為溫室效應氣體量節節升高，

we keep releasing into the atmosphere.

而且我們還繼續將其釋放到大氣中。

You all know that.

你們都知道的。

But what I assume you might not have heard

但是我猜你們大概沒聽說過，

is that one of the most important things our human society could do

我們人類社會為對付氣候變遷 所能做的一件重要事項

to address climate change

lies right there in the soil.

就躺在土壤中。

I'm a soil scientist who has been studying soil since I was 18,

我是土壤科學家， 從 18 歲起就開始研究土壤，

because I'm interested in unlocking the secrets of soil

因為我對揭開土壤的秘密很有興趣，

and helping people understand this really important climate change solution.

也很想幫助眾人了解 這件極為重要的氣候變遷解方。

So here are the facts about climate.

所以先講一下氣候的實情。

The concentration of carbon dioxide in the earth's atmosphere

地球大氣二氧化碳的濃度

has increased by 40 percent

僅在過去 150 年 就已經增加了 40%。

just in the last 150 years or so.

Human actions are now releasing 9.4 billion metric tons of carbon

人類的行為現在釋放 94 億公噸的碳

into the atmosphere,

進入大氣，

from activities such as burning fossil fuels

各式行為如焚燒石化燃料、

and intensive agricultural practices,

密集農業，

and other ways we change the way we use land,

我們改變使用土地的方法，

including deforestation.

包括砍伐森林。

But the concentration of carbon dioxide that stays in the atmosphere

但是大氣的二氧化碳濃度

is only increasing by about half of that,

卻只增加一半，

and that's because half of the carbon we keep releasing into the atmosphere

那是因為我們持續排放至大氣層的碳

is currently being taken up by land and the seas

有一半被土地及海洋吸收，

through a process we know as carbon sequestration.

我們稱這個過程為碳封存。

So in essence, whatever consequence you think we're facing

所以基本上，無論你認為我們

from climate change right now,

會因現在的氣候變遷而面對哪種後果，

we're only experiencing the consequence of 50 percent of our pollution,

我們都只經歷 50% 因污染而造成的後果，

because the natural ecosystems are bailing us out.

因為自然生態系統替我們紓困。

But don't get too comfortable,

但是千萬不要心存大意，

because we have two major things working against us right now.

因為我們有兩個 主要的東西在跟我們作對。

One: unless we do something big,

第一：除非我們有大規模

and then fast,

而且快速的行動，

emissions will continue to rise.

不然排放量會持續增加。

And second: the ability of these natural ecosystems

第二：這些自然生態系統

to take up carbon dioxide from the atmosphere

能從大氣層吸收二氧化碳

and sequester it in the natural habitats

並將之封存在各種自然環境的能力，

is currently getting compromised,

目前正受到危害，

as they're experiencing serious degradation because of human actions.

因為它們也因人類的行為 而遭受非常嚴重的退化。

So it's not entirely clear

所以我們並不全然清楚

that we will continue to get bailed out by these natural ecosystems

這些自然生態系統 是否還能幫助我們脫離困境，

if we continue on this business-as-usual path that we've been.

如果我們還是一切照舊。

Here's where the soil comes in:

而這就是土壤可以介入之處：

there is about three thousand billion metric tons of carbon in the soil.

大約有三兆公噸的碳存在土壤中。

That's roughly about 315 times the amount of carbon

那大約是我們目前釋放 到大氣中的 315 倍。

that we release into the atmosphere currently.

And there's twice more carbon in soil than there is in vegetation and air.

而且碳在土裡的量 比在植被及空氣中的量還多兩倍。

Think about that for a second.

讓我們稍微思考一下。

There's more carbon in soil

碳在土裡的量

than there is in all of the world's vegetation,

比在全球植被中的量還多，

including the lush tropical rainforests and the giant sequoias,

這植被包括鬱鬱蔥蔥的 熱帶雨林及巨杉、

the expansive grasslands,

廣闊的草原、

all of the cultivated systems,

所有的耕地，

and every kind of flora you can imagine on the face of the earth,

及每一種你能想到長在地表的植物相，

plus all the carbon that's currently up in the atmosphere, combined,

還有目前正在大氣中的碳量，

全部加起來，還多二倍。

and then twice over.

Hence, a very small change in the amount of carbon stored in soil

因此，在土壤中儲存的碳量 只要有一點點改變，

can make a big difference in maintenance of the earth's atmosphere.

就會對維護地球的大氣層 造成很大的不同。

But soil's not just simply a storage box for carbon, though.

但是土壤不僅僅是一個碳的儲藏盒，

It operates more like a bank account,

它的運作更像是銀行帳戶，

and the amount of carbon that's in soil at any given time

任何時刻，土壤中的碳量

is a function of the amount of carbon coming in and out of the soil.

是土壤碳量進出的函數。

Carbon comes into the soil through the process of photosynthesis,

碳經由光合作用進入土壤，

when green plants take carbon dioxide from the atmosphere

因為綠色植物會從大氣吸進二氧化碳

and use it to make their bodies,

來製造植物本體，

and upon death, their bodies enter the soil.

死亡的時候，植物本體就進入土壤。

And carbon leaves the soil

碳會離開土壤

and goes right back up into the atmosphere

回到大氣層，

when the bodies of those formerly living organisms

因為原本是活的生物體

decay in soil by the activity of microbes.

死後會因土壤微生物的活動而腐爛。

See, decomposition releases carbon dioxide into the atmosphere,

你看，腐化作用會釋放 二氧化碳進入大氣中，

as well as other greenhouse gases such as methane and nitrous oxide,

也會釋放其它溫室效應氣體， 如甲烷及一氧化氮，

but it also releases all the nutrients we all need to survive.

但它也會釋放我們生存 所需的所有營養物。

One of the things that makes soil such a fundamental component

土壤之所以能成為

任何氣候變遷緩解策略的 基本要素之一，

of any climate change mitigation strategy

is because it represents a long-term storage of carbon.

就是因為它代表著碳的長期儲存。

Carbon that would have lasted maybe a year or two

原本只能在地表上的腐化殘渣中 留存一兩年的碳，

in decaying residue if it was left on the surface

can stay in soil for hundreds of years, even thousands and more.

可以在土中存留數百年 甚至數千年還不只。

Soil biogeochemists like me

像我這樣的生物地球化學家，

study exactly how the soil system makes this possible,

研究土壤系統 究竟如何使這成為可能，

by locking away the carbon in physical association with minerals,

怎樣把碳以物理性的締和作用，

inside aggregates of soil minerals,

封存在土壤礦物質集合體內部，

and formation of strong chemical bonds

形成強化學鍵

that bind the carbon to the surfaces of the minerals.

將碳綁在礦物質表面。

See when carbon is entrapped in soil,

你看，當碳被鎖在土中，

in these kinds of associations with soil minerals,

以這種締合作用與土壤礦物質結合，

even the wiliest of the microbes can't easily degrade it.

即使是最賊的微生物 也無法輕易地讓它腐化。

And carbon that's not degrading fast

不會快速降解的碳

is carbon that's not going back into the atmosphere as greenhouse gases.

就不會回到大氣中成為溫室效應氣體。

But the benefit of carbon sequestration

但是碳封存的好處

is not just limited to climate change mitigation.

不僅限於減緩氣候變遷。

Soil that stores large amounts of carbon is healthy, fertile, soft.

儲存大量碳的土 很健康、肥沃、柔軟。

It's malleable. It's workable.

它具延展性、可塑性。

It makes it like a sponge.

碳使土壤像海綿。

It can hold on to a lot of water and nutrients.

它可以緊緊抓住很多水和營養物。

Healthy and fertile soils like this

像這樣健康且肥沃的土

support the most dynamic, abundant and diverse habitat for living things

支持著最有活力、最豐富 且多樣化的棲息地，

that we know of anywhere on the earth system.

給地球上無所不在的生物居住。

It makes life possible for everything from the tiniest of the microbes,

它讓生命變成可能；

無論是最小的微生物，

such as bacteria and fungi,

像細菌和真菌，

all the way to higher plants,

一直到更高等的植物，

and fulfills the food, feed and fiber needs for all animals,

並且滿足所有動物 對食物、飼料及纖維的需求，

including you and I.

包括你我。

So at this point, you would assume that we should be treating soil

所以此刻你可能已經假設 我們應該看待土壤

like the precious resource that it is.

像寶貴的資源，而它的確是。

Unfortunately, that's not the case.

可惜，並非如此。

Soils around the world are experiencing unprecedented rates of degradation

全世界的土壤都在遭受 史無前例的退化率，

through a variety of human actions that include deforestation,

因各種人類活動而然， 包括砍伐森林、

intensive agricultural production systems,

集約農業生產系統、

overgrazing,

過度放牧、

excessive application of agricultural chemicals,

過度施用農藥、

erosion and similar things.

侵蝕及類似的事情。

Half of the world's soils are currently considered degraded.

目前全世界有一半的土壤 被視為劣質。

Soil degradation is bad for many reasons,

從很多原因來看 土壤退化都是件壞事，

but let me just tell you a couple.

我就舉幾個例子。

One: degraded soils have diminished potential to support plant productivity.

一：退化的土壤 會減少植物生產力的潛力。

And hence, by degrading soil,

因此，由於土壤退化，

we're compromising our own abilities to provide the food and other resources

我們也在連累自己 提供食物及其它資源的能力，

that we need for us

這些資源不但是我們需要的，

and every member of living things on the face of the earth.

地表上每一種生物也都需要。

And second:

第二：

soil use and degradation, just in the last 200 years or so,

僅僅在過去二百年左右， 土壤使用及退化

has released 12 times more carbon into the atmosphere

已經釋放 12 倍的碳 進入大氣層中，

compared to the rate at which we're releasing carbon

相較於目前我們釋放碳

into the atmosphere right now.

進入大氣層的比率。

I'm afraid there's even more bad news.

很不幸的還有更多壞消息。

This is a story of soils at high latitudes.

這是個高緯度土壤的故事。

Peatlands in polar environments

極地環境的泥炭地

store about a third of the global soil carbon reserves.

存著三分之一的全球土壤碳儲量。

These peatlands have a permanently frozen ground underneath,

這些泥碳地下面 有一層永久冰凍的土，

the permafrost,

永凍土，

and the carbon was able to build up in these soils over long periods of time

時間一久，碳就在這種土壤裡聚積，

because even though plants are able to photosynthesize during the short,

因為雖然植物能在短暫、

warm summer months,

溫暖的夏季月分行光合作用，

the environment quickly turns cold and dark,

它的環境很快就變得又冷又暗，

and then microbes are not able to efficiently break down the residue.

所以微生物不能 有效率地分解殘留物。

So the soil carbon bank in these polar environments

所以在這些極地環境內的土壤碳儲存

built up over hundreds of thousands of years.

就在過去數萬年慢慢累積。

But right now, with atmospheric warming,

但是現在，因為大氣暖化，

the permafrost is thawing and draining.

永凍土開始解凍、排水。

And when permafrost thaws and drains,

當永凍土解凍、排水，

it makes it possible for microbes to come in

就會讓微生物進入

and rather quickly decompose all this carbon,

並相對快速地分解這些碳，

with the potential to release hundreds of billions of metric tons of carbon

有可能釋放以兆公噸計的碳

into the atmosphere in the form of greenhouse gases.

進入大氣層，變成溫室效應氣體。

And this release of additional greenhouse gases into the atmosphere

這份進入大氣層的額外溫室氣體

will only contribute to further warming

只會造成進一步的暖化，

that makes this predicament even worse,

使得這種困境更加嚴重，

as it starts a self-reinforcing positive feedback loop

因為它開始自我強化的正回饋循環，

that could go on and on and on,

可以不斷持續，

dramatically changing our climate future.

大幅改變我們的氣候未來。

Fortunately, I can also tell you that there is a solution

幸好，我也可以告訴你們 的確有解決的方法，

for these two wicked problems of soil degradation and climate change.

能解決土壤退化及氣候變遷 這兩個邪惡的問題。

Just like we created these problems,

就像我們製造了這些問題，

we do know the solution,

我們的確知道解決的方法，

and the solution lies in simultaneously working

而且解決的方法就是

要同時一起對付這兩件事，

to address these two things together,

through what we call climate-smart land management practices.

用我們稱為氣候智慧型土地管理規範。

What do I mean here?

我是指什麼意思呢？

I mean managing land in a way that's smart

我是指用一種智慧方法來管理土地，

about maximizing how much carbon we store in soil.

最佳化我們能在土壤中儲存的碳量。

And we can accomplish this

我們可以做到這一點，

by putting in place deep-rooted perennial plants,

藉著種植深根性的多年生植物，

putting back forests whenever possible,

盡可能的復育森林，

reducing tillage and other disturbances from agricultural practices,

減少來自農法的耕作和其他干擾，

including optimizing the use of agricultural chemicals and grazing

包括最佳化使用農藥及放牧，

and even adding carbon to soil, whenever possible,

甚至盡可能加碳到土壤中——

from recycled resources such as compost and even human waste.

用回收資源的方法 如堆肥甚至是人類排泄物。

This kind of land stewardship is not a radical idea.

這種土地管理 並不是一種激進的想法。

It's what made it possible for fertile soils

這是讓肥沃土壤

to be able to support human civilizations since time immemorial.

從遠古時代就能 養活人類文明的方法。

In fact, some are doing it just right now.

事實上，有些國家 正在從事這樣的方法。

There's a global effort underway to accomplish exactly this goal.

目前全球正在齊心努力 完成這個目標。

This effort that started in France is known as the "4 per 1000" effort,

這項活動始於法國的千分之四倡議，

and it sets an aspirational goal

它設了一個很有抱負的目標，

to increase the amount of carbon stored in soil by 0.4 percent annually,

每年要增加 0.4% 碳在土中的儲量，

using the same kind of climate-smart land management practices

用我剛剛提過的同樣方法， 氣候智慧型土地管理規範。

I mentioned earlier.

And if this effort's fully successful,

如果這項嘗試能完全達標，

it can offset a third of the global emissions

就能抵銷掉全球三分之一

of fossil-fuel-derived carbon into the atmosphere.

因石化燃料衍生的碳 釋放入大氣層的排放量。

But even if this effort is not fully successful,

但是即使這項嘗試不能完全達標，

but we just start heading in that direction,

我們還是朝著那個方向前進，

we still end up with soils that are healthier, more fertile,

我們還是得到更健康更肥沃的土壤，

are able to produce all the food and resources that we need

可以生產我們所需的食物及資源，

for human populations and more,

給人類及其他生物使用，

and also soils that are better capable

而且土壤也更有能力

of sequestering carbon dioxide from the atmosphere

自大氣層吸存二氧化碳，

and helping with climate change mitigation.

幫助緩解氣候變遷。

I'm pretty sure that's what politicians call a win-win solution.

我很確定政治家會稱之為 雙贏解決方案。

And we all can have a role to play here.

而且我們都可以在這裡 扮演一個角色。

We can start by treating the soil with the respect that it deserves:

我們可以從給予土壤 應有的尊重開始：

respect for its ability as the basis of all life on earth,

尊重它身為地球 所有生命的基礎的能力，

respect for its ability to serve as a carbon bank

尊重它儲存碳的能力，

and respect for its ability to control our climate.

也尊重它控制氣候的能力。

And if we do so,

如果我們這麼做，

we can then simultaneously address

我們就可以同時解決

two of the most pressing global challenges of our time:

我們這個時代 兩個最急迫的全球挑戰：

climate change and soil degradation.

氣候變遷及土壤退化。

And in the process, we would be able to provide food and nutritional security

在此過程，

我們還可以提供糧食及營養安全

to our growing human family.

給我們日益成長的人類家庭。

Thank you.

謝謝。

(Applause)

（掌聲）