水荒，如此近

有多少河流干涸成裸露的荒灘？有多少農田因缺水而荒蕪？有多少生命因得不到水資源遭遇生死考驗？人口增長、氣候變化以及人們生活方式的轉變已使全球水荒愈演愈烈。但這樣迫在眉睫的危機似乎并沒有引起所有人的關注，很多人仍然以為自己觸手可及的潔凈水源取之不盡、用之不竭，或者以為“危言聳聽”的水荒離自己萬里之遙。可惜現實總比想象殘酷，下面這篇文章告訴你：水荒，離我們如此之近。

Angry protesters filled the streets of Karachi1） last week， clogging traffic lanes and public squares until police and paratroopers2） were forced to intervene. That’s not rare in Pakistan， which is often a site of political and religious violence.

But last week’s protests had nothing to do with freedom of expression， drone wars3）， or Americans. They were about access to water. When Khawaja Muhammad Asif， the Minister of Defense， Power， and Water （yes， that is one ministry）， warned that the country’s chronic water shortages could soon become uncontrollable， he was looking on the bright side. The meagre4） allotment of water available to each Pakistani is a third of what it was in 1950. As the country’s population rises， that amount is falling fast.

Dozens of other countries face similar situations—not someday， or soon， but now. Rapid climate change， population growth， and a growing demand for meat （and， thus， for the water required to grow feed for livestock） have propelled them into a state of emergency. Millions of words have been written， and scores of urgent meetings have been held， since I last wrote about this issue， nearly a decade ago； in that time， things have only grown worse.

The various physical calamities5） that confront the world are hard to separate， but growing hunger and the struggle to find clean water for billions of people are clearly connected. Each problem fuels others， particularly in the developing world—where the harshest impact of natural catastrophes has always been felt. Yet the water crisis challenges even the richest among us.

California is now in its fourth year of drought， staggering through its worst dry spell6） in twelve hundred years； farmers have sold their herds， and some have abandoned crops. Cities have begun rationing7） water. According to the London-based organization Wateraid， water shortages are responsible for more deaths in Nigeria than Boko Haram8）； there are places in India where hospitals have trouble finding the water required to sterilize9） surgical tools.

Nowhere， however， is the situation more acute than in Brazil， particularly for the twenty million residents of S?o Paulo. “You have all the elements for a perfect storm， except that we don’t have water，” a former environmental minister told Lizzie O’Leary10）， in a recent interview for the radio show Marketplace. The country is bracing for riots. “There is a real risk of social convulsion11），” José Galizia Tundisi， a hydrologist with the Brazilian Academy of Sciences， warned in a press conference last week. He said that officials have failed to act with appropriate urgency. “Authorities need to act immediately to avoid the worst.” But people rarely act until the crisis is directly affecting them， and at that point it will be too late.

It is not that we are actually running out of water， because water never technically disappears. When it leaves one place， it goes somewhere else， and the amount of freshwater on earth has not changed significantly for millions of years. But the number of people on the planet has grown exponentially12）； in just the past century， the population has tripled， and water use has grown sixfold. More than that， we have polluted much of what remains readily13） available—and climate change has made it significantly more difficult to plan for floods and droughts.

Success is part of the problem， just as it is with the pollution caused by our industrial growth. The standard of living has improved for hundreds of millions of people， and the pace of improvement will quicken. As populations grow more prosperous， vegetarian life styles often yield to a Western diet， with all the disasters that implies. The new middle classes， particularly in India and China， eat more protein than they once did， and that， again， requires more water use. （On average， hundreds of gallons of water are required to produce a single hamburger.）

Feeding a planet with nine billion residents will require at least fifty per cent more water in 2050 than we use today. It is hard to see where that water will come from. Half of the planet already lives in urban areas， and that number will increase along with the pressure to supply clean water.

“Unfortunately， the world has not really woken up to the reality of what we are going to face， in terms of the crises， as far as water is concerned，” Rajendra Pachauri， the chairman of the International Panel on Climate Change， said at a conference on water security earlier this month. “If you look at agricultural products， if you look at animal protein， the demand for which is growing—that’s highly water intensive. At the same time， on the supply side， there are going to be several constraints. Firstly because there are going to be profound changes in the water cycle due to climate change.”

Floods will become more common， and so will droughts， according to most assessments of the warming earth. “The twenty-first-century projections make the [previous] mega-droughts14） seem like quaint15） walks through the garden of Eden，” Jason Smerdon， a climate scientist at Columbia University’s Lamont-Doherty Earth Observatory， said recently. At the same time， demands for economic growth in India and other developing nations will necessarily increase pollution of rivers and lakes. That will force people to dig deeper than ever before into the earth for water.

There are ways to replace oil， gas， and coal， though we won’t do that unless economic necessity demands it. But there isn’t a tidy and synthetic invention to replace water. Conservation would help immensely， as would a more rational use of agricultural land—irrigation today consumes seventy per cent of all freshwater.

The result of continued inaction is clear. Development experts， who rarely agree on much， all agree that water wars are on the horizon16）. That would be nothing new for humanity. After all， the word “rivals” has its roots in battles over water—coming from the Latin， rivalis， for “one taking from the same stream as another.” It would be nice to think that， with our complete knowledge of the physical world， we have moved beyond the limitations our ancestors faced two thousand years ago. But the truth is otherwise； rivals we remain， and the evidence suggests that， until we start dying of thirst， we will stay that way.

上周（編注：英文原文發表于2015年2月24日），憤怒的抗議者涌上卡拉奇街頭，堵塞了行車道和公共廣場，直到警察和傘兵迫不得已出動干預才作罷。在巴基斯坦這樣一個經常發生政治與宗教暴力事件的地方，這并不罕見。

但是，上周的抗議活動無關乎言論自由、無人機戰爭抑或是美國人，而是與獲取水資源有關。（巴基斯坦）國防與水電部（沒錯，這是一個部）部長赫瓦賈·穆罕默德·阿西夫曾發出警告，稱該國長期面臨的缺水問題可能很快會陷入失控的局面。而這還是樂觀的說法。巴基斯坦現在的人均可用水量少得可憐，僅為1950年時的三分之一。隨著該國人口的增長，這一數量還在急劇下滑。

其他許多國家也面臨類似的情況—不是在將來或不久之后，而是現在。快速的氣候變化、人口增長以及對肉類食品需求的持續增長（由此帶來的家畜養殖用水需求的增長）已經使這些國家在用水方面進入緊急狀態。我上一次撰寫關于這一問題的文章是在將近十年前，從那時起，人們寫過很多這方面的文章，也開過很多次緊急會議，而情況在這期間只是變得越來越糟糕。

各種自然災害之間存在千絲萬縷的關系，道不明理不清，但是日趨嚴重的饑荒與難以為數十億人找到潔凈水間的關聯卻一目了然。每個問題的出現都會加劇其他問題，在發展中國家更是如此—一直以來，自然災害對這些國家的影響都最嚴重。然而，就水資源危機而言，我們當中最富裕的國家也遭到了挑戰。

加利福尼亞今年已是連續第四年遭遇干旱，艱難地經歷了1200年來最嚴重的干旱期。農民紛紛賣掉牲畜，有的已棄種農作物。城市開始限量供水。據總部位于倫敦的“水援助”組織稱，在尼日利亞，缺水問題比極端組織博科圣地造成的死亡人數更多；而在印度的一些地方，醫院則很難找到用來消毒手術器具的水。

不過，形勢最急迫的還要數巴西，尤其是圣保羅的兩千萬居民。“在這里，刮起一場“完美風暴”的所有條件都已具備，只差水資源。”一位前環境部部長最近在電臺節目《市場報道》的訪談中對麗齊·奧利瑞說。該國正在準備應對騷亂。“真的有發生社會動亂的風險。”巴西科學院水文學家何塞·加利齊亞·唐迪思在上周的一次新聞發布會上警告說。他說官方沒有采取適當的緊急行動：“當局需要立即行動起來，以防止最壞的結果出現。”但是，人們大多會無動于衷，直到危機對自己造成切身影響才會行動起來，而那時就為時已晚了。

我們并非真的會將水耗盡，因為從技術層面看，水永遠不會消失。當它離開一個地方，就會去另一個地方。數百萬年來，地球上的淡水總量并未發生顯著變化。但地球上的人口數量卻呈現幾何數級的增長。僅上個世紀，人口就增長了兩倍，而用水量是原來的六倍。不僅如此，我們還對很多現成水資源造成了污染，氣候變化也使得應對洪水和干旱變得更加艱難。

正如工業發展會造成污染一樣，成功也是造成水資源問題的因素之一。數以億計的人生活水平得以提高，而且提高的步伐還會加快。隨著人們的生活變得日益富裕，素食生活習慣往往會讓位于西方飲食習慣，伴隨而來的是其可能引發的各種災難。各國尤其是印度和中國的新一代中產階級較以往食用更多的蛋白質，而這又需要使用更多的水。（一般而言，僅僅制作一個漢堡包，就需要數千加侖的水。）

到2050年，養活一個有著90億居民的地球所需的水量將至少比我們現在多50%。我們很難預見這些水從何處獲得。地球上已有一半人生活在城市地區，這一數字還會上升，而潔凈水的供應壓力也在加大。

“不幸的是，就水資源而言，世界尚未真正意識到我們將要面臨的危機，”在這個月早些時候一次有關用水安全的會議上，國際氣候變化委員會主席拉金德拉·帕喬里說，“看看農產品和動物蛋白，你就會發現，對二者的需求一直在增長，而這些都是水消耗量極高的產業。與此同時，水的來源將受到諸多限制。首要原因在于，由于氣候變化，水循環將會發生深刻變化。”

從大多數對變暖的地球的評估來看，洪水和干旱將日益普遍。“鑒于對21世紀形勢的預測，（之前發生的）大干旱就算是好的了，就像在伊甸園里的優雅漫步。”哥倫比亞大學拉蒙特-多爾蒂地球觀測站的氣候學家杰森·斯默登最近表示。與此同時，在印度及其他一些發展中國家，經濟增長的需求必將加重對河流和湖泊的污染。這將迫使人們在開采地下水源時比以往任何時候都挖得更深。

要想找到石油、天然氣和煤的替代物，是有辦法的，雖然除非經濟發展需要，否則我們并不會這樣做。但是還沒有一種令人滿意的新合成物可以用來代替水。節約用水非常有幫助，更合理地運用耕地也同樣大有裨益—目前灌溉用水占淡水總用量的70%。

繼續無所作為的后果顯而易見。在很多問題上經常各執己見的發展專家們都一致認為，爭水之戰已經初露端倪。對人類而言，這不是什么新鮮事。畢竟，英語單詞“rivals”（對手）原本就根源于因水而起的戰斗—這個詞源自拉丁語“rivalis”，意思是“與別人爭奪同一條溪流的人”。我們覺得自己憑著對自然界的充分了解，已經走出了我們的祖先在兩千年前身處的困境。這種想法是挺好，但事實卻是另一回事：我們依然是彼此的“對手”，而且有證據表明，除非我們被渴死，否則會始終處于這種狀態。

10.Lizzie O’Leary：麗齊.奧利瑞，美國公共媒體（American Public Media）旗下的電臺欄目《市場報道》主持人，曾任CNN記者。

11.convulsion [k?n?v?l?（?）n] n. 動亂，騷動；災變

12.exponentially [?eksp??nen?（?）li] adv. （增長）呈幾何數級地

13.readily [?red?li] adv. 容易地

14.mega-drought：大干旱

15.quaint [kwe?nt] adj. 奇特而有趣的

16.on the horizon：出現端倪