Why wildfires have gotten worse -- and what we can do about it | Paul Hessburg

譯者: Lilian Chiu 審譯者: Helen Chang

As you've probably noticed,

你們可能已經注意到，

in recent years, a lot of western forests have burned

近年來，有很多西部的森林

in large and destructive wildfires.

遭到毀滅性的大型野火摧殘。

If you're like me --

如果你們和我一樣，

this western landscape is actually why my family and I live here.

像這樣的西部風景，就是我和 我的家人會住在這裡的原因。

And as a scientist and a father,

身為科學家和父親，

I've become deeply concerned about what we're leaving behind

我非常關切我們會留下什麼給

for our kids, and now my five grandkids.

我們的孩子，和我現在的五個孫子。

In the US, an area that's larger than the state of Oregon has burned

在美國，僅在過去十年間，

被火燒毀的面積就比奧勒崗州還大，

in just the last 10 years,

and tens of thousands of homes have been destroyed.

數萬個家園因此被摧毀。

Acres burned and homes destroyed have steadily increased

過去三十年間，被燒毀的土地面積 和被摧毀的家園數目

over the last three decades,

一直穩定在增加，

and individual fires that are bigger than 100,000 acres --

而面積大於十萬英畝的個別火災數目

they're actually on the rise.

事實上是在增加的。

These are what we call "megafires."

我們稱這些大火為「超級大火」。

Megafires are the result of the way we've managed this western landscape

超級大火發生的原因， 是我們過去 150 年來，

over the last 150 years

在穩定持續暖化的氣候下，

in a steadily warming climate.

經營這塊西部地景的方式。

Much of the destruction that we are currently seeing

我們目前看到的破壞，

其實大多數是本來可以避免的。

could actually have been avoided.

I've spent my entire career studying these western landscapes,

我的整個職涯都在 研究這些西部地景，

and the science is pretty clear:

科學是非常明確的：

if we don't change a few of our fire-management habits,

如果不改變我們 管理大火的一些習慣，

we're going to lose many more of our beloved forests.

我們將會失去更多更多鍾愛的森林。

Some won't recover in our lifetime

有些是在我們一生中， 甚至我們孩子的一生中，

or my kids' lifetime.

都無法復元的。

It's time we confront some tough truths about wildfires,

該是時候了，該來面對 關於野火的棘手真相了，

and come to understand that we need to learn to better live with them

要了解，我們必須學習 和它們共處得更好一些，

and change how they come to our forests,

並改變它們如何來到我們的森林、

our homes

我們的家園、

and our communities.

我們的社區。

So why is this happening?

所以，為什麼會發生？

Well, that's what I want to talk to you about today.

這就是今天我想和大家談的。

You see this forest?

看到這座森林了嗎？

Isn't it beautiful?

它很美，不是嗎？

Well, the forests that we see today

我們現今看到的森林，

look nothing like the forests of 100 or 150 years ago.

一點也不像 100 或 150 年前的森林。

Thankfully, panoramic photos were taken in the 1930s

謝天謝地，1930 年代時，

自西部山頂瞭望所 拍攝了數千個全景照片，

from thousands of western mountaintop lookouts,

and they show a fair approximation

靠這些照片，我們可以大略呈現出

of the forest that we inherited.

我們所繼承的森林的樣貌。

The best word to describe these forests of old is "patchy."

要形容這些老森林， 最好的詞就是「拼湊成的」。

The historical forest landscape was this constantly evolving patchwork

歷史的森林地景， 是不斷演化的拼湊之作，

of open and closed canopy forests of all ages,

由各種年齡，稀疏與鬱閉的 冠層森林拼湊而成，

and there was so much evidence of fire.

有好多大火燒過的痕跡。

And most fires were pretty small by today's standards.

用現今的標準來看， 大部份的火災規模都算很小。

And it's important to understand that this landscape was open,

重要的是要了解這是個稀疏的地景，

with meadows and open canopy forests,

有草地，也有稀疏冠層森林；

and it was the grasses of the meadows

是草地上的草，

and in the grassy understories of the open forest

以及稀疏森林中長滿草的林下層，

that many of the wildfires were carried.

被許多野火燒了過去。

There were other forces at work, too, shaping this historical patchwork:

還有其他的力量 形成這個歷史上的拼湊物，

for example, topography, whether a place faces north or south

比如：地形學，地形朝南或朝北，

or it's on a ridge top or in a valley bottom;

是在山脊上或是在谷底；

elevation, how far up the mountain it is;

海拔高度，在山上多高的地方；

and weather, whether a place gets a lot of snow and rain,

是否常常下雪或是下雨，

sunlight and warmth.

是否有陽光且溫暖。

These things all worked together

所有這些元素加在一起，

to shape the way the forest grew.

造成森林成長的方式。

And the way the forest grew shaped the way fire behaved

而森林成長的方式，

就會形成大火在地景上的行為方式。

on the landscape.

There was crosstalk between the patterns and the processes.

在模式和過程之間互相干擾影響。

You can see the new dry forest.

如你所見，左側是新的乾燥森林。

Trees were open grown and fairly far apart.

樹木開放成長，且間距算是遠的。

Fires were frequent here, and when they occurred,

大火常常在這裡發生，

發生時都不會太嚴重，

they weren't that severe,

while further up the mountain,

再往山上一點，

in the moist and the cold forests,

中間是潮濕且寒冷的森林，

trees were more densely grown and fires were less frequent,

樹木的密度比較高， 比較不常發生大火，

but when they occurred, they were quite a bit more severe.

但一旦發生大火， 通常會比較嚴重一些。

These different forest types, the environments that they grew in

不同類型的森林、它們的生長環境，

and fire severity -- they all worked together

以及大火的猛烈程度， 通通作用在一起，

to shape this historical patchwork.

形成了這個歷史的拼湊之作。

And there was so much power

在這個拼湊之作當中，

in this patchwork.

有著非常大的力量。

It provided a natural mechanism

它提供了一個自然機制，

to resist the spread of future fires across the landscape.

來抵抗未來的大火， 不讓它們在地景上擴散。

Once a patch of forest burned,

一旦森林其中一塊被燒掉，

it helped to prevent the flow of fire across the landscape.

它能協助防止大火延燒至地景各處。

A way to think about it is,

可以把它看待成，

the burned patches helped the rest of the forest

森林中被燒毀的那些部份，

能協助維持剩下的森林仍然是森林。

to be forest.

Let's add humans to the mix.

讓我們混合考量人類的因素。

For 10,000 years, Native Americans lived on this landscape,

美國原住民在這地景上住了一萬年，

and they intentionally burned it -- a lot.

他們常常會刻意放火，

They used fire to burn meadows and to thin certain forests

用火燒草原，讓某些森林變得稀疏，

so they could grow more food.

來種更多的食物。

They used fire to increase graze

他們用火來增加牧草的量，

for the deer and the elk and the bison that they hunted.

供獵獲的鹿、麋和野牛食用。

And most importantly, they figured out

最重要的是

他們了解如果在春天和秋天放火，

if they burned in the spring and the fall,

they could avoid the out-of-control fires of summer.

就能避免夏天失控的大火。

European settlement -- it occurred much later, in the mid-1800s,

很久之後，歐洲人 於十九世紀中期開始殖民，

and by the 1880s, livestock grazing was in high gear.

1880 年代到達家畜放牧的高點。

I mean, if you think about it, the cattle and the sheep ate the grasses

我的意思是，試想牛和羊要吃草，

which had been the conveyer belt for the historical fires,

這些草地曾是史上火災的輸送帶，

and this prevented once-frequent fires from thinning out trees

使得以前頻繁的大火

不再能夠稀疏樹木、燒光枯木。

and burning up dead wood.

Later came roads and railroads, and they acted as potent firebreaks,

然後出現了道路和鐵路， 它們成了非常有效的防火道，

interrupting further the flow of fire across this landscape.

進一步阻斷大火延燒至地景各處。

And then something happened which caused a sudden pivot

接下來發生的事使社會突然轉變。

in our society.

In 1910, we had a huge wildfire.

1910 年，有一場大野火，

It was the size of the state of Connecticut.

大小和康乃迪克州一樣大。

We called it "the Big Burn."

我們稱之為「大火燒（Big Burn）」。

It stretched from eastern Washington to western Montana,

它的範圍從華盛頓州的東邊 一路延伸到蒙大拿州的西邊，

and it burned, in a few days, three million acres,

幾天之內就燒毀了三百萬英畝的地，

devoured several towns, and it killed 87 people.

吞滅了數個小鎮，

造成 87 人死亡，

Most of them were firefighters.

大部份是消防員。

Because of the Big Burn, wildfire became public enemy number one,

這次的大火燒使得野火 成了全民的頭號公敵，

and this would shape the way that we would think about wildfire

塑造我們社會在接下來百年間

in our society

for the next hundred years.

對於野火的看法。

Thereafter, the Forest Service, just five years young at the time,

其後，當時成立才五年的林務局

was tasked with the responsibility of putting out all wildfires

被賦予重任，

要消滅公地上所有的野火，

on 193 million acres of public lands,

多達 193 百萬英畝的面積。

and they took this responsibility

他們非常認真地看待這項責任，

very seriously.

They developed this unequaled ability to put fires out,

發展出無與倫比的滅火能力，

and they put out 95 to 98 percent

每年 95% 至 98% 的全美國大火

of all fires every single year in the US.

被他們撲滅掉。

And from this point on, it was now fire suppression

從此之後，

撲滅火災取代了野火，

and not wildfires

that would become a prime shaper of our forests.

成為我們森林成形的主要因素。

After World War II, timber harvesting got going in the west,

二次世界大戰後，

西部開始伐木，

and the logging removed the large and the old trees.

砍伐原木造成大樹和老樹消失。

These were survivors of centuries of wildfires.

它們原是百年來野火下的倖存者。

And the forest filled in.

森林接著填補上來，

Thin-barked, fire-sensitive small trees filled in the gaps,

對火敏感的薄皮小樹木補滿了空隙，

and our forests became dense, with trees so layered and close together

我們的森林變成高密度，

樹木近近疊在一起，會彼此碰觸；

that they were touching each other.

So fires were unintentionally blocked by roads and railroads,

道路和鐵路無意間阻斷火的蔓延；

the cattle and sheep ate the grass,

牛和羊吃草；

then along comes fire suppression and logging, removing the big trees,

接著而來的人為滅火、 伐木和砍掉大樹，

你們可知道發生了什麼事？

and you know what happened?

All these factors worked together

所有這些因素一起作用，

to allow the forest to fill in,

森林填補了間隙，

creating what I call the current epidemic of trees.

造成我稱為「目前樹木氾濫的疫情」。

(Laughter)

（笑聲）

Go figure.

去想想吧。

(Laughter)

（笑聲）

More trees than the landscape can support.

樹木的數量遠超過 地景能夠支持的量。

So when you compare what forests looked like 100 years ago and today,

因此，比較百年前和現今的森林，

the change is actually remarkable.

改變其實很驚人。

Notice how the patchwork has filled in.

注意看拼湊之作是怎麼被填補的。

Dry south slopes --

原本乾燥的南面山坡

they're now covered with trees.

現在被樹木覆蓋滿了。

A patchwork that was once sculptured by mostly small

曾經主要由中小型的火災 所塑成的拼湊之作

and sort of medium-sized fires

has filled in.

已經被填補滿了。

Do you see the blanket of trees?

看到樹木的覆蓋層了嗎？

After just 150 years,

僅僅經過 150 年，

we have a dense carpet of forest.

已經有了一片高密度的森林。

But there's more.

還不只如此。

Because trees are growing so close together,

因為樹木生長的距離非常近，

and because tree species, tree sizes and ages

因為長在大片區域中的樹木，

are so similar across large areas,

種類、尺寸、年齡都太相似，

fires not only move easily from acre to acre,

火勢不但很容易從 一英畝延燒到下一英畝，

but now, so do diseases and insect outbreaks,

發生的疾病和昆蟲疫情 也一樣容易傳播，

which are killing or reducing the vitality

因此造成現在的森林

of really large sections of forest now.

大片區域地死亡或衰弱。

And after a century without fire,

一整個世紀沒有火災之後，

dead branches and downed trees on the forest floor,

在森林地面上的枯枝和倒樹

they're at powder-keg levels.

處在一觸即發的層級。

What's more, our summers are getting hotter

此外，夏天越來越熱，

and they're getting drier

越來越乾燥，

and they're getting windier.

風也越來越大 。

And the fire season is now 40 to 80 days longer each year.

如今每年的火季長了 40~80 天。

Because of this, climatologists are predicting

因此，氣候學家預測，

that the area burned since 2000

自 2000 年起燒掉區域的面積，

will double or triple

在接下來三十年間會 變為兩倍或三倍。

in the next three decades.

And we're building houses in the middle of this.

而我們在這其中蓋房子。

Two recently published studies tell us

兩份近期發佈的研究告訴我們，

that more than 60 percent of all new housing starts are being built

超過 60% 的新住房

被建築在這種可燃且危險的地方。

in this flammable and dangerous mess.

So when we do get a fire,

所以一旦發生火災，

large areas can literally go up in smoke.

會有大片的面積化為灰燼。

How do you feel now

現在你們對於我一開始

about the forest image

讓各位看的那張森林圖片

that I first showed you?

感覺如何？

It scares the heck out of me.

它把我嚇壞了。

So what do we do?

我們應該怎麼做？

We need to restore the power of the patchwork.

我們得要恢復拼湊之作的力量。

We need to put the right kind of fire

我們得要把「對」的那種火

back into the system again.

再次放回到系統當中。

It's how we can resize the severity of many of our future fires.

這種方式能讓我們改變 許多未來火災的嚴重程度。

And the silver lining is that we have tools

讓人感到欣慰的是

我們有工具，

and we have know-how to do this.

也有該怎麼做的實際知識。

Let's look at some of the tools.

咱們來看看其中一些工具。

We can use prescribed burning to intentionally thin out trees

我們可以用計畫性火燒（控制燒除）

來刻意讓樹木變稀疏，

and burn up dead fuels.

並燒盡可燃物。

We do this to systematically reduce them and keep them reduced.

這麼做可以系統性地減少 並保持它們於少量。

And what is that going to do?

那會有什麼結果？

It's going to create already-burned patches on the landscape

那會在地景上創造出 已經燒光的區塊，

that will resist the flow of future fires.

能夠防止未來大火的竄燒。

We can combine mechanical thinning with some of these treatments

我們可以把機械式的稀疏做法 和這類處理方式結合，

where it's appropriate to do so,

在適當的情況下這麼做，

and capture some commercial value

並獲得一些商業價值，

and perhaps underwrite some of these treatments,

也許還能承保這類處理方式，

especially around urban areas.

特別是在都市地區。

And the best news of all is that prescribed burning produces

最好的消息是計畫性火燒所產生的煙

so much less smoke than wildfires do.

遠遠少於野火產生的煙。

It's not even close.

差距很大。

But there's a hitch:

但有個問題：

prescribed burning smoke is currently regulated under air quality rules

依目前空氣品質規定的規範，

計畫性火燒的煙是可避免的妨礙行為。

as an avoidable nuisance.

But wildfire smoke?

但野火的煙呢？

It simply gets a pass.

它沒被規範。

Makes sense, doesn't it? (Laughs)

合理嗎？（笑聲）

So you know what happens?

所以會發生什麼事？

We do far too little prescribed burning,

我們計畫性的火燒做得太少了，

and we continually eat smoke in the summers

因而使我們在夏天 持續吸入來自超級大火的煙。

from megafires.

We all need to work together to get this changed.

我們得要同心協力來改變這一點。

And finally, there's managed wildfires.

最後，還有管制野火。

Instead of putting all the fires out,

不要撲滅所有的野火，

we need to put some of them back to work

得要讓其中一些繼續燒下去，

thinning forests and reducing dead fuels.

讓森林變稀疏，減少乾枯的可燃物。

We can herd them around the landscape

我們可以在地景上「放牧」野火，

when it's appropriate to do so

在適當的情況下這樣做，

to help restore the power of the patchwork.

就能協助恢復拼湊之作的力量。

And as you've probably figured out by now,

現在你們可能已經想通了，

this is actually a social problem.

這其實是個社會問題。

It's got ecological and climate explanations,

它的確有生態上和氣候上的解釋，

but it's a social problem, and it will take us humans to solve it.

但它是個社會問題， 需要我們人類來解決。

Public support for these tools is poor.

沒有多少大眾支持這些工具。

Prescribed burning and managed wildfires are not well-supported.

計畫性火燒和管制野火 並沒有受到很好的支持。

We actually all simply want fires to magically go away

事實上我們只想要大火 神奇地自己熄滅掉，

and take that pesky smoke with them, don't we?

也一併帶走討厭的煙，對吧？

But there is no future without lots of fire and lots of smoke.

但未來不可能沒有 多場火災和很多的煙。

That option is actually not on the table.

其實桌面上並沒有這選項。

Until we, the owners of public lands, make it our high priority

直到公共土地的所有者

將這問題列為優先，

to do something about the current situation,

針對目前的情況行動，

we're going to experience continued losses to megafires.

不然我們就會繼續經歷 超級大火造成的損失。

So it's up to us.

所以，決定權在我們的手上。

We can spread this message to our lawmakers,

我們可以把這訊息傳給立法者，

folks who can help us manage our fires

給那些能夠協助我們 管制大火和森林的人。

and our forests.

If we're unsuccessful,

如果我們沒能成功，

where will you go to play

當你最喜歡的地方被燒到焦黑時，

你要到哪裡去玩？

when your favorite places are burned black?

Where will you go

你要去哪裡

to breathe deep

緩慢地深呼吸？

and slow?

Thank you.

謝謝。

(Applause)

（掌聲）