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You may have seen images like this all over social media.
想必大家已经看到这些图片已经刷爆各大社交媒体了。
The Amazon rainforest is burning, and these images have, understandably, caused international alarm,
亚马逊雨林着火了，这些照片引起了国际社会的警惕，不过这也情有可原，
with media outlets, NGO’s and politicians all weighing in on the conversation about the value of one of the most unique and biodiverse ecosystems on the planet.
各大媒体，非政府组织和政客们也都加入了关于地球上最独特，生物多样性最丰富的生态系统之一的价值的讨论。
Amidst all the discussion, one particular claim has stood out:
在所有的讨论中，有一个主张格外显眼：
that the forests of the Amazon are the lungs of the Earth, producing 20% of the world’s oxygen.
亚马逊雨林是地球之肺，世界上20%的氧气都产自这里。
But, that’s not exactly right.
问题是，这一说法并不完全正确。
Now, the Amazon is the world’s largest remaining rainforest, covering between 6-8 million square km of land,
亚马逊的确是世界上现存最大的雨林，占地600~800万平方公里，
holding millions of species, from plants to insects, birds, and mammals, many of which are yet to be discovered by researchers.
拥有数以百万计的物种，从植物到昆虫、再到鸟类和哺乳动物一应俱全，其中有许多物种都还有待研究人员发现。
However, it’s an ecosystem that is compromised.
然而，这个生态系统已经反复受到危害。
This year more than 74,000 fires have been recorded in Brazil, most of which are in the Amazon region.
今年，巴西发生的有记录的火灾就已经有74000多起了，其中大部分都发生在亚马逊地区。
And because of this, many are wondering if the deforestation taking place in the Amazon will have a negative impact on our global oxygen supply,
正因为如此，许多人都好奇，发生在亚马逊的森林砍伐行为是否会影响到全球的氧气供应，
which in turn, has led to the claim that the Amazon produces 20% of the world’s oxygen.
亚马逊生产了全世界20%的氧气这种说法就来源于后者。
So where exactly did this figure come from?
那么问题来了，这个数据到底是从哪里得来的呢？
“This misunderstanding arises from the fact that the Amazon accounts for roughly 20% of the land surface photosynthesis on the planet,
“这种误解源于这样一个事实，即亚马逊雨林光合作用的体量约占地球陆地表面总体量的20%，
and photosynthesis produces oxygen and takes our carbon dioxide from the atmosphere.
光合作用就会产生氧气并带走大气中的二氧化碳。
But the bigger issue is that it misunderstands what happens to that oxygen, and where our long term oxygen resource comes from.
然而，更重要的是，上述误解误解了那些氧气后来的归宿，也误解了我们长期的氧气来源。
And the key thing to understand is that most ecosystems consume as much oxygen as they produce.
问题的关键点在于，大多数生态系统消耗的氧气和它们产生的氧气的量是大致相当的。
In other words, we can assume that the Amazon probably consumes the same amount of oxygen that it creates.
也就是说，我们可以假设，亚马逊河消耗的氧气和它产生的氧气一样多。
“We estimate that about 60% of the oxygen produced by plants is consumed by plants as well for their metabolism.
“据我们估计，植物产生的氧气大概有60%都会被植物自身以新陈代谢的形式消耗掉。
And the remainder is consumed by microbes, in particular, as they're consuming dead organic material, and we estimate that's somewhere around 40%.
剩下的大部分会被以死去的有机物为食的微生物消耗掉，据我们估计，这个比例在40%左右。
So overall, in terms of oxygen supply,
所以，总的来说，就氧气供应而言，
the Amazon and almost any other biome on Earth is pretty close to zero, in the net amount of oxygen it provides.”
就提供的净供氧量而言，亚马逊河和地球上几乎所有其他生物群一样，都接近于零。”
The biggest contributor to Earth’s oxygen supply is actually within our oceans:
对地球氧气供应贡献最大的实际上是海洋：
around half of Earth’s oxygen is generated from marine organisms through photosynthesis.
地球上大约一半的氧气都是海洋生物通过光合作用产生的。
Phytoplankton are one of the primary producers, using carbon dioxide, water, and solar energy to create their food and produce oxygen as a byproduct.
利用二氧化碳、水和太阳能来制造食物，并产生氧气这一副产品的浮游植物就是主要的功臣之一。
Okay, so you might be wondering if we did lose the Amazon completely, what would happen to Earth’s atmosphere?
好吧，你或许会想，如果亚马逊雨林彻底没了，地球的大气层会怎样？
Unlike carbon dioxide, which has quite a low concentration in the atmosphere, with carbon dioxide at around 400 parts per million,
和二氧化碳不同，大气中二氧化碳浓度很低，具体在400ppm（(1ppm=百万分之一)左右，
oxygen is 21% of the atmosphere, so the atmosphere is awash in oxygen.
氧气的浓度占到了大气的21%，所以大气中氧气的含量是很多的。
And so, if the Amazon was entirely disappear in flames,
所以，如果亚马逊被大火烧得一干二净了，
the concentration of oxygen in the atmosphere would dip by just a tiny fraction of a percent.
大气中氧气的浓度只会下降1%的一个零头。
However, the Amazon still remains a crucial part of our global ecosystem.
尽管如此，亚马逊依然是地球生态系统至关重要的一个组成部分。
It regulates regional rainfall and by extension, the global climate,
雨林里深入地底的树根能够获取地下的水分将其循环回大气，
through deep tree roots that can access water and recirculate it back to the atmosphere, generating moisture that can produce clouds and rainfall.
变成能产生云和雨的水分，继而调节区域降雨甚至是全球的气候。
Most importantly, it acts as a carbon sink thanks to the process of photosynthesis, and that would be the biggest threat we’d face if we lost this rainforest.
最重要的是，它通过光合作用起到了碳汇的作用，如果我们失去了这片雨林，失去这一碳汇将成为我们面临的最大威胁。
“So if the entire Amazon rainforest were to disappear, atmospheric CO2 concentrations would increase by around 10%,
“所以，如果整个亚马逊雨林消失了，大气中二氧化碳的浓度将会增加10%左右，
which may sound like a small number, and it is, compared to our fossil fuel emissions.
听上去你可能觉得这个数字并不大，与我们的化石燃料排放相比也确实是如此。
But if this were to happen,
但如果真的发生这种情况，
our chances of stabilizing atmospheric CO2 concentrations at a level that we can say within a safe climate zone would be much, much more challenging.”
那我们将大气中的二氧化碳浓度稳定在一个相对安全的气候区内的任务就会变得艰巨得多。”
So, all this is to say, that as the world considers how to protect the Amazon,
所以，说这么多，宗旨就是，既然现在全世界都在关注如何保护亚马逊这个问题，
it’s important to make sure that we’re equipped with the right facts when having these discussions.
确保讨论时我们掌握的事实准确无误是很重要的。
“I think this relates to the idea of the lungs of the Earth, which I think is a fine metaphor,
“我认为这个问题与地球之肺这一概念有关，我个人觉得这个比喻还是很贴切的，
if you just use it as a poetic metaphor of how important Amazon is.
如果将其理解为一个比喻亚马逊雨林有多重要的诗意修辞的话。
I prefer to think of it as a global cooling system or a global pump.
我更愿意把它想象成地球的一个冷却系统或泵。
There are plenty of strong scientific reasons to protect the Amazon, to value the Amazon.
保护亚马逊，珍视亚马逊这一命题是有很多强有力的科学依据支撑的。
And it's good to make the case for the Amazon based on where the science is strong.
用强有力的科学来为亚马逊正名是件好事。
It's dangerous to make a case of something that actually is a flawed scientific concept.”
但把有缺陷的科学概念作为案例的依据是很危险的。”
If you liked this episode, let us know in the comments below, and check out this video on what a cloudless world would look like.
如果喜欢本期视频，请在下面的评论中告诉我们，大家不妨再看看这段有关没有了云，世界会变成什么样的视频。
Make sure to subscribe, and thanks for watching.
记得订阅噢，感谢大家的收看。
