Whatever happened to the hole in the ozone layer? - Stephanie Honchell Smith

567,165 views ・ 2023-04-18

TED-Ed


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翻译人员: Jenny Zhao 校对人员: Jacky He
00:07
In the 1980s, the world faced a huge problem:
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上世纪 80 年代, 我们世界面临一个巨大的问题:
00:11
there was a rapidly expanding hole in the ozone layer.
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臭氧层中有一个 正在迅速扩大的空洞。
00:14
So, what happened? And is it still there?
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所以,发生了什么事? 这个空洞还在吗?
00:17
Let’s go back to the beginning.
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让我们先从头开始。
00:19
The Sun makes life on Earth possible,
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太阳让地球上的生物能够存活,
00:21
but too much exposure to its UV radiation damages plant and animal DNA.
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但过量的紫外线辐射 会损害植物和动物的 DNA。
00:27
Thankfully, about 98% of that radiation is absorbed by ozone molecules
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值得庆幸的是,大约 98% 的 辐射被臭氧分子吸收
00:32
dispersed in the stratosphere,
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分散在平流层;
00:34
which are continuously broken apart and reformed in this process,
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它们在此过程中 不断地分解和重造,
00:38
maintaining a delicate equilibrium.
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保持着一个微妙的平衡。
00:40
But in the early 1970s, two chemists— Mario Molina and Sherwood Rowland—
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但在 1970 年代初期,两位化学家 ——马里奥·莫利纳和舍伍德·罗兰——
00:46
demonstrated that widely used chemicals called chlorofluorocarbons, or CFCs,
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证实人们广泛使用的 一种化学物质氯氟烃或 CFC,
00:52
could upset this balance.
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可能会打破这种平衡。
00:54
CFCs were developed in the 1920s by three US-based corporations
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CFC是在 1920 年代 由三个美国公司开发的
00:58
as coolants for refrigerators.
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用于冰箱的冷却剂。
01:01
Unlike existing alternatives— such as ammonia or methyl chloride—
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不同于现有的替代品 —如氨或氯甲烷—
01:05
CFCs were non-flammable and non-toxic—
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CFC 不易燃且无毒—
01:08
meaning they wouldn't burst into flames or cause deadly gas leaks.
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这意味着它不会起火 或导致致命的气体泄漏。
01:12
They also made great propellants, foaming agents, and fire-retardants.
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用它还可以制造很好的 推进剂,发泡剂和阻燃剂。
01:16
CFCs soon found their way into a variety of everyday items
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CFC 很快就被加入 各种日常用品中
01:20
and became a multi-billion dollar per year industry.
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并成为了一个年收益 数十亿美元的产业。
01:23
In the lower atmosphere, CFCs don’t break down or react with other molecules.
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在低层大气中,CFC 不会分解 或与其他分子发生反应。
01:29
But Molina and Rowland showed that in the stratosphere,
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但莫利纳和罗兰 表明了在平流层里,
01:32
they're broken apart by UV light, releasing chlorine atoms.
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它们被紫外线分解, 释放出氯原子,
01:36
These then react with ozone,
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而其与臭氧发生反应,
01:37
destroying it faster than it can be replenished.
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将其消除,远超过臭氧再生的速率。
01:40
A single chlorine atom can destroy thousands of ozone molecules
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一个氯原子可以破坏 数千个臭氧分子,
01:44
before finally reacting with something else and forming a stable molecule.
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在最终与其他物质反应 并形成稳定的分子之前。
01:48
Seeing the threat to their bottom line,
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看到对他们根基的威胁之后,
01:50
CFC producers pushed back to discredit the scientists,
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CFC 生产商开始诋毁科学家,
01:54
even accusing them of working for the KGB.
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甚至指控他们为 KGB 工作。
01:57
Initial estimates showed that within 60 years,
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初步估计表明在 60 年内,
02:01
CFCs could reduce ozone concentrations by 7%.
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CFC 可使臭氧浓度降低 7%。
02:04
But by 1985, it became clear that ozone depletion, especially over Antarctica,
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但到了 1985 年,很明显 臭氧的消耗,尤其在南极上空的
02:10
was happening much faster.
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发生得快很多。
02:12
Here, the extremely cold temperatures and unique structure of Antarctic clouds
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在这儿,极寒的温度 和独特的南极云层结构
02:16
accelerated ozone loss.
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加速了臭氧的损失。
02:18
Scientists stationed in Antarctica noticed a massive drop
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驻扎在南极洲的科学家 注意到了每年春天
02:21
in overhead ozone occurring every spring.
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上空臭氧的大幅下降。
02:24
Satellite data revealed the vast extent of these losses
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卫星数据揭露了这些 损失的具体程度,
02:27
and chemical tests confirmed that the cause was unquestionably CFCs.
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而化学测试证实, 无疑是 CFC 导致的。
02:33
NASA soon released visualizations, which were broadcast around the world
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美国国家航空航天局很快便发布了 视图,并在全世界播出
02:37
and captured public attention.
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引起了公众的注意。
02:39
If ozone depletion continued, rates of skin cancer would skyrocket.
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如果臭氧消耗继续下去, 皮肤癌的发病率将会飙升。
02:43
Photosynthesis would be impaired, making plants—
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光合作用会受危害,使植物—
02:46
including rice, wheat, and corn—
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包括大米,小麦和玉米—
02:48
less productive and more susceptible to disease.
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生产力降低,更容易染病。
02:52
Global agricultural production would plummet,
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全球农业产量将直线下降,
02:54
and entire ecosystems would collapse.
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并且整个生态系统都会崩溃。
02:57
But many politicians— weighing immediate economic concerns over long-term ones—
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但许多政客,考虑眼前的 而非长期的经济问题,
03:02
disagreed about what to do.
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在提出方案的时候出现了分歧。
03:04
The fight to ban CFCs found two unlikely allies
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禁止 CFC 的斗争中 形成了一对不寻常的盟友,
03:07
in US President Ronald Reagan and UK Prime Minister Margaret Thatcher.
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美国总统罗纳德·里根 和英国首相玛格丽特·撒切尔。
03:11
Despite their general opposition to government regulation,
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尽管他们反对政府管控,
03:14
Reagan, who had undergone treatment for skin cancer,
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因皮肤癌而接受治疗的里根,
03:17
and Thatcher, who was trained as a chemist,
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还有接受化学教育的 撒切尔夫人,
03:20
recognized the need for immediate action.
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认识到了采取立刻行动的必要性。
03:23
The US and UK, along with Canada, Norway, Sweden, and Finland,
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美国和英国以及加拿大, 挪威,瑞典和芬兰,
03:27
led calls for an international ban on CFCs.
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带头呼吁国际上 禁用 CFC。
03:30
In 1987, representatives signed the Montreal Protocol,
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1987年,代表们签署了 《蒙特利尔议定书》,
03:34
requiring the rapid phasing out of CFCs
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要求迅速淘汰 CFC,
03:36
and creating a fund to assist Global South countries
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并建立一项基金来 援助全球南方国家
03:39
in obtaining affordable, non-ozone depleting alternatives.
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以利用经济的,不损耗臭氧的替代品。
03:43
It was later ratified by every country on Earth—
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它后来由地球上全部国家批准—
03:46
the only treaty in history to achieve this.
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历史上唯一实现 这一目标的条约。
03:49
In 1995, Molina, Rowland, and their Dutch colleague Paul Crutzen,
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1995年,莫利纳,罗兰和 他们的荷兰同事保罗·克鲁岑,
03:54
were jointly awarded the Nobel Prize in Chemistry.
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共同获得了诺贝尔化学奖。
03:57
As the use of CFCs declined,
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随着 CFC 的使用逐渐减少,
03:59
the ozone hole began shrinking,
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臭氧空洞开始缩小了,
04:01
and is predicted to disappear entirely by 2070.
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预计到2070年将完全消失。
04:04
But we’re not out of the woods yet.
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但我们还没有完全走出困境。
04:06
While the ban was a win for the climate, as CFCs are potent greenhouse gases,
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这个禁令对气候十分有利; CFC 是强效温室气体,
04:10
the alternatives that replaced them— hydrofluorocarbons, or HFCs— are too.
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而取代它们的替代品, 氢氟碳化物,即 HFC 也是。
04:16
While generally less potent than CFCs,
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虽然通常不及 CFC,
04:18
HFCs still trap more heat than carbon dioxide
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HFC 仍然较二氧化碳 留住更多的热量
04:22
and are contributing to climate change.
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并且正在加剧气候变化。
04:24
To address this, in 2016, the Kigali Amendment
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为了解决这个问题,2016年, 基加利修正案
04:27
was added to the Montreal Protocol,
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被加入了《蒙特利尔议定书》,
04:29
calling for an 85% cut in global HFCs by 2047.
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呼吁在 2047 年实现 全球 HFC 85% 的削减。
04:33
This alone could avoid up to 0.5°C of global warming by the end of the century.
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到本世纪末,仅此一项就可以 避免高达 0.5 ℃ 的全球变暖。
04:39
Today, as we face the existential threat of climate change,
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今天,当我们面临气候 变化的生存威胁时,
04:43
the Montreal Protocol serves as a model for the decisive global cooperation
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我们需要像《蒙特利尔议定书》这类 全球决定性合作典范
04:47
we need to combat it.
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以对付它。
04:48
The question is, what will it take for us to come together again?
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那么问题来了; 什么会让我们再次团结起来?
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