Stronger hurricanes.

較強的颶風。

More intense heatwaves and floods.

更強烈的熱浪和洪水。

Across the world, climate events are getting more extreme.

在世界各地，氣候事件越來越極端。

And while there's little doubt that global warming is to blame,

雖然毫無疑問，全球變暖是罪魁禍首。

proving that fault for specific weather events hasn't really been possible… until now.

證明特定天氣事件的過錯是不可能的... 直到現在。

An emerging field called extreme-event attribution is helping us measure and verify the relationship

一個被稱為極端事件歸因的新興領域正在幫助我們測量和驗證以下關係

between the climate crisis and extreme weather.

氣候危機與極端天氣之間的關係。

Not only does this have huge implications for predicting and modeling our planet's future,

這不僅對預測和模擬我們地球的未來有巨大的意義。

but it could also help us better prepare for living in an increasingly extreme world.

但它也可以幫助我們更好地準備生活在一個越來越極端的世界裡。

For a long time, there was a distinction between climate and weather.

長期以來，氣候和天氣是有區別的。

And the reality is, extreme events are where we most acutely feel the climate system.

而現實是，極端事件是我們對氣候系統感受最敏銳的地方。

It's critical that we understand how global warming is impacting the extremes.

我們必須瞭解全球變暖是如何影響極端情況的。

Because that's where the impacts from climate change are being played out.

因為那是氣候變化帶來的影響正在發揮作用的地方。

When we talk about the impacts of the climate crisis, we're really talking about distinguishing the influence of natural factors

當我們談論氣候危機的影響時，我們實際上是在談論如何區分自然因素的影響。

from anthropogenic factors on Earth's climate cycle.

人為因素對地球氣候週期的影響；

Basically, this means teasing apart Earth's natural climate cycles from human-caused climate change.

基本上，這意味著將地球的自然氣候週期與人類造成的氣候變化分開。

A way to begin doing this is to examine the “fingerprints” we humans have left behind on Earth's climate.

開始做這件事的一個方法是檢查我們人類在地球氣候上留下的 "指紋"。

For example, our ice core records tell us that CO2 levels have risen by almost 50% in the last 150 years,

例如，我們的冰芯記錄告訴我們，在過去的150年裡，二氧化碳水準上升了近50%。

and records show that since the industrial age began over a century ago,

和記錄顯示，自一個多世紀前工業時代開始。

many regions of the world have warmed by more than 1.5 degrees Celsius.

世界許多地區的氣溫上升了1.5攝氏度以上。

By matching both the observed and modeled patterns of Earth's climate,

通過匹配觀察到的和模擬的地球氣候模式。

scientists can positively identify the “fingerprints'' associated with these changes.

科學家們可以積極地識別與這些變化相關的 "指紋"。

Following the tracks of these fingerprints has helped scientists link climate change with more general trends,

追蹤這些指紋的蹤跡，有助於科學家將氣候變化與更普遍的趨勢聯繫起來。

like rising sea levels and global temperatures.

如海平面上升和全球氣溫。

But verifying the role of human influence on specific climate events, like Hurricane Harvey or the California drought?

但驗證人類對具體氣候事件的影響作用，如颶風哈維或加州乾旱？

That's not as easy.

那就沒那麼容易了。

It's precisely this problem of attributing specific extreme weather events to climate change

恰恰是這種把具體的極端天氣事件歸結為氣候變化的問題

that researchers like Dr. Diffenbaugh are working on.

像Diffenbaugh博士這樣的研究人員正在研究的。

While we can't yet say for sure that these events wouldn't have happened without climate change,

雖然我們還不能肯定地說，如果沒有氣候變化，這些事件就不會發生。

we can talk about the probability of them happening… and how those odds are changing.

我們可以討論它們發生的概率... 以及這些概率是如何變化的。

By comparing our climate predictions with how things actually play out,

通過比較我們對氣候的預測和事情的實際發展情況。

researchers can start to develop a real-world framework for posing and testing hypotheses.

研究人員可以開始開發一個現實世界的框架，用於提出和檢驗假設。

But the work doesn't stop there.

但工作並沒有停止。

Observational data can only tell us if there's a change in the intensity or frequency of an event;

觀測數據只能告訴我們一個事件的強度或頻率是否有變化。

it still can't tell us what caused those changes.

它仍然不能告訴我們是什麼原因導致這些變化。

This is where computer modeling comes in.

這就是計算機建模的作用。

We can't run experiments on the global climate system. We can't stick the climate system in a lab.

我們不能在全球氣候系統上做實驗 We can't run experiments on the global climate system.我們不能把氣候系統放在實驗室裡。

But we can say, our extreme event attribution framework predicts a probability

但我們可以說，我們的極端事件歸因框架預測了一個概率。

of record-setting heat over a region of Europe to be X percent,

的創紀錄的，在歐洲某地區的熱度為X%。

and then we can wait and watch and see how often record-setting temperatures occur.

然後我們就可以靜觀其變，看看創紀錄的溫度出現的頻率有多高。

These computer models can use real-world climate influences, like how much CO2 is present in the atmosphere,

這些計算機模型可以使用現實世界的氣候影響因素，如大氣中存在多少二氧化碳。

to create a more complete timeline of extreme events.

以建立一個較為完整的極端事件時間軸。

Or, they can create hundreds of hypothetical histories that span thousands of years to test our world against.

或者，他們可以創造數百個假設的歷史，跨越數千年的時間來檢驗我們的世界。

This allows researchers to look at the world without human-caused climate change,

這使得研究人員能夠在沒有人類造成的氣候變化的情況下觀察這個世界。

and assess the probability of events happening.

並評估事件發生的概率。

By comparing the probability between Earths with and without climate change,

通過比較地球有無氣候變化的概率。

researchers can begin to quantify the changes in risk...

研究人員可以開始量化風險的變化...。

and test how much the frequency and magnitude of extreme events have changed over time.

並測試極端事件的發生頻率和幅度隨著時間的推移有多大變化。

Over the past decade, the emerging field of extreme event attribution has used these tools

在過去的十年裡，新興的極端事件歸因領域使用了這些工具

to help researchers find strong evidence of climate change's relationship to changing events like heat,

以幫助研究人員找到氣候變化與熱等變化事件關係的有力證據。

as well as tropical cyclones, wildfires, sea ice coverage, and flooding.

以及熱帶氣旋、野火、海冰覆蓋和洪水。

By combining observational records with climate models and our growing knowledge of how

通過將觀測記錄與氣候模型結合起來，以及我們日益增長的關於如何進行觀測的知識。

global warming affects Earth's natural processes,

全球變暖會影響地球的自然進程。

we're also getting better at distinguishing between the roles that human influence on the climate system

我們也越來越擅長區分人類對氣候系統的影響的作用

and climate variability play in specific climate events.

和氣候變異性在具體氣候事件中的作用。

Being able to attribute specific climate events to climate change is extremely useful on many fronts.

能夠將具體的氣候事件歸結為氣候變化，在許多方面都非常有用。

For one, it can help researchers develop better climate models that can then be used by governments

首先，它可以幫助研究人員開發更好的氣候模型，然後供政府使用

to inform climate action plans.

為氣候行動計劃提供資訊；

It can also help us better understand the impact we're having on the climate and be better equipped to brace for these impacts.

它還可以幫助我們更好地瞭解我們對氣候的影響，並更好地準備好應對這些影響。

A lot of our infrastructure, a lot of our planning is, is designed around, statistical analyses

我們的很多基礎設施，我們的很多規劃都是圍繞著統計分析而設計的。

that assume stationarity in the climate system.

假設氣候系統中的靜止性；

If the global warming that's already happened has already changed the odds of those extremes,

如果已經發生的全球變暖已經改變了這些極端情況的發生機率。

then everything that we've designed and built based on that, there's risk of those thresholds being exceeded.

那麼我們在此基礎上設計和建造的所有東西，都有可能超過這些門檻。

The infrastructure in many communities, from sidewalks to levees to storm surge barriers,

許多社區的基礎設施，從人行道到防洪堤，再到風暴潮屏障。

is built and managed based on the probability of the recurrence of climatic extremes.

是根據極端氣候發生的概率來建設和管理的。

For cities sitting on a floodplain, the likelihood of a major flood happening in a given year

對於位於洪泛區的城市來說，在某一年發生大洪水的可能性為

will often determine how resilient their levees and dams must be.

往往會決定他們的堤壩和大壩必須有多大的彈性。

If a city uses the 100-year floodplain as its threshold,

如果一個城市以100年洪泛區作為門檻。

that means that its levees and dams are built to anticipate the 1% chance that a major flood could happen in any given year.

這意味著它的防洪堤和大壩的建造是為了預測1%的可能性，即大洪水可能在任何一年發生。

But the probability of these thresholds being exceeded is changing,

但是，這些門檻被超過的概率正在發生變化。

and the fact is that too many communities just aren't adequately prepared.

而事實是，太多的社區只是沒有做好充分的準備。

Extreme events don't just affect and disrupt essential infrastructure.

極端事件不僅僅是影響和破壞重要的基礎設施。

They can have an outsized effect on public health, our food supply, and our global economy.

它們會對公眾健康、食品供應和全球經濟產生巨大影響。

The idea is that by being better able to know what to expect from the climate crisis,

這個想法是，通過能夠更好地瞭解氣候危機的預期。

the world can brace for the worst while making informed decisions to stop the worst from happening.

世界可以為最壞的情況做好準備，同時做出明智的決定，阻止最壞情況的發生。

We see it year after year in the US and around the world.

我們在美國和世界各地年復一年地看到它。

We're living with a world where unprecedented, extreme events are more likely. They're happening more often.

我們生活在一個前所未有的極端事件更有可能發生的世界裡。它們正在更頻繁地發生。

We're living with that now.

我們現在就生活在這樣的環境中。

And the impacts of those extremes are growing the cost that we're bearing.

而這些極端情況的影響，讓我們承擔的成本越來越大。

While extreme event attribution is helping us more confidently connect the dots between climate change

雖然極端事件的歸因正在幫助我們更有信心地將氣候變化之間的聯繫聯繫起來。

and individual weather events, it's still a very new field and there's a lot to learn.

和個人氣象事件，這還是一個很新的領域，有很多東西需要學習。

Check out our video here on how scientists are modeling a world without clouds.

請看我們的視頻，科學家們正在模擬一個沒有云的世界。

Don't forget to subscribe to Seeker, and as always, thanks for watching.

不要忘了訂閱《求是》，一如既往的感謝大家的觀看。