第1780-a期:Are we running out of clean water?

From space, our planet appears to be more ocean than Earth. But despite the water covering 71% of the planet’s surface, more than half the world’s population endures extreme water scarcity for at least one month a year. And current estimates predict that by 2040, up to 20 more countries could be experiencing water shortages. Taken together, these bleak statistics raise a startling question: are we running out of clean water?

从太空看，我们的星球似乎比地球更像海洋。但是，尽管水覆盖了地球表面 71% 的面积，但世界上有一半以上的人口每年至少要忍受一个月的极度缺水。目前的估计预测，到 2040 年，将有多达 20 个国家面临缺水问题。总而言之，这些惨淡的统计数据提出了一个令人吃惊的问题：我们的清洁水用完了吗？

Well yes, and no. At a planetary scale, Earth can’t run out of freshwater thanks to the water cycle, a system that continuously produces and recycles water, morphing it from vapour, to liquid, to ice as it circulates around the globe. So this isn’t really a question of how much water there is, but of how much of it is accessible to us. 97% of earth’s liquid is saltwater, too loaded with minerals for humans to drink or use in agriculture. Of the remaining 3% of potentially usable freshwater, more than two-thirds is frozen in ice caps and glaciers. That leaves less than 1% available for sustaining all life on Earth, spread across our planet in rivers, lakes, underground aquifers, ground ice and permafrost. It’s these sources of water that are being rapidly depleted by humans, but slowly replenished by rain and snowfall.

嗯，是的，没有。在行星尺度上，由于水循环，地球不会耗尽淡水，水循环是一个不断产生和循环水的系统，当水在全球循环时，水从蒸汽变成液体，再变成冰。所以这实际上不是有多少水的问题，而是我们可以获得多少水的问题。地球上 97% 的液体是盐水，富含矿物质，人类无法饮用或用于农业。在剩余 3% 的潜在可用淡水中，超过三分之二被冻结在冰盖和冰川中。剩下不到 1% 可用于维持地球上的所有生命，分布在我们星球的河流、湖泊、地下含水层、地面冰和永久冻土中。正是这些水源正在被人类迅速耗尽，但通过降雨和降雪慢慢补充。

And this limited supply isn’t distributed evenly around the globe. Diverse climates and geography provide some regions with more rainfall and natural water sources, while other areas have geographic features that make transporting water much more difficult. And supplying the infrastructure and energy it would take to move water across these regions is extremely expensive.

而且这种有限的供应在全球范围内分布不均。不同的气候和地理条件为一些地区提供了更多的降雨和天然水源，而其他地区的地理特征使输水变得更加困难。并且提供将水运过这些地区所需的基础设施和能源是极其昂贵的。

In many of these water-poor areas, as well as some with greater access to water, humanity is guzzling up the local water supply faster than it can be replenished. And when more quickly renewed sources can’t meet the demand, we start pumping it out of our finite underground reserves. Of Earth’s 37 major underground reservoirs, 21 are on track to be irreversibly emptied. So while it’s true that our planet isn’t actually losing water, we are depleting the water sources we rely on at an unsustainable pace.

在许多这些缺水地区，以及一些更容易获得水资源的地区，人类消耗当地供水的速度超过了补充的速度。当更新速度更快的资源无法满足需求时，我们便开始从有限的地下储量中抽取资源。在地球的 37 个主要地下水库中，有 21 个正在被不可逆转地清空。因此，虽然我们的星球确实没有真正失去水资源，但我们正在以不可持续的速度耗尽我们赖以生存的水源。

This might seem surprising – after all, on average, people only drink about two liters of water a day. But water plays a hidden role in our daily lives, and in that same 24 hours, most people will actually consume an estimated 3000 liters of water. In fact, household water – which we use to drink, cook, and clean – accounts for only 3.6% of humanity’s water consumption. Another 4.4% goes to the wide range of factories which make the products we buy each day. But the remaining 92% of our water consumption is all spent on a single industry: agriculture.

这似乎令人惊讶——毕竟，平均而言，人们每天只喝大约两升水。但水在我们的日常生活中起着隐藏的作用，在同样的 24 小时内，大多数人实际上会消耗大约 3000 升水。事实上，我们用来饮用、做饭和清洁的家庭用水仅占人类用水量的 3.6%。另外 4.4% 用于生产我们每天购买的产品的各种工厂。但我们剩余的 92% 的用水量都花在了一个行业：农业。

Our farms drain the equivalent of 3.3 billion Olympic-sized swimming pools every year, all of it swallowed up by crops and livestock to feed Earth’s growing population. Agriculture currently covers 37% of Earth’s land area, posing the biggest threat to our regional water supplies. And yet, it’s also a necessity. So how do we limit agriculture’s thirst while still feeding those who rely on it?

我们的农场每年消耗的水量相当于 33 亿个奥林匹克规格的游泳池，所有这些都被庄稼和牲畜吞没，以养活地球上不断增长的人口。农业目前占地球陆地面积的 37%，对我们的区域供水构成最大威胁。然而，这也是必要的。那么，我们如何在满足依赖农业的人们的同时限制农业的饥渴呢？

Farmers are already finding ingenious ways to reduce their impact, like using special irrigation techniques to grow “more crop per drop”, and breeding new crops that are less thirsty. Other industries are following suit, adopting production processes that reuse and recycle water. On a personal level, reducing food waste is the first step to reducing water use, since one-third of the food that leaves farms is currently wasted or thrown away. You might also want to consider eating less water-intensive foods like shelled nuts and red meat. Adopting a vegetarian lifestyle could reduce up to one third of your water footprint. Our planet may never run out of water, but it doesn’t have to for individuals to go thirsty. Solving this local problem requires a global solution, and small day-to-day decisions can affect reservoirs around the world.

农民们已经在寻找巧妙的方法来减少它们的影响，比如使用特殊的灌溉技术“每滴水种植更多的作物”，以及培育不太渴的新作物。其他行业也纷纷效仿，采用再利用和循环水的生产工艺。就个人而言，减少食物浪费是减少用水的第一步，因为目前有三分之一离开农场的食物被浪费或扔掉了。您可能还想考虑少吃水分密集型食物，如带壳坚果和红肉。采用素食生活方式可以减少多达三分之一的水足迹。我们的星球可能永远不会缺水，但个人不必口渴。解决这个局部问题需要一个全球性的解决方案，而日常的小决策可能会影响世界各地的水库。