新滅絕時代

2009-12-31 00:00:00ＢｙＢｒｙａｎＷａｌｓｈ

新東方英語 2009年10期

已在長江中生活了2，500萬年的白鰭豚如今再也難覓蹤影，這種被稱為“長江女神”，大腦表面積比海豚大，比長臂猿和黑猩猩更聰明的珍稀淡水生哺乳豚就這樣在我們這一代的手中永久地消失了。然而，它們的滅絕并非出于“物競天擇”;將它們趕盡殺絕的，正是人類。如今，新一波物種大滅絕即將到來，而作為萬物之靈的我們，是繼續充當毀滅物種的劊子手，還是行動起來創造一個萬物共生的星球?

Madagascar1)—which separated from India 80 million to 100 million years ago before eventually settling off the southeastern coast of Africa—is in many ways an Earth apart. All that time in geographic isolation made Madagascar a Darwinian playground， its animals and plants evolving into forms utterly original.

Once lushly forested， Madagascar has seen more than 80% of its original vegetation cut down or burned since humans arrived at least 1，500 years ago， fragmenting habitats and leaving animals effectively homeless. Unchecked hunting wiped out a number of large species， and today mining， logging and energy exploration threaten those that remain.

Madagascar is a conservation hot spot—a term for a region that is very biodiverse and particularly threatened. Conservationists estimate that extinctions worldwide are occurring at a pace that is up to 1，000 times as great as history’s background rate before human beings began proliferating2). Worse， that die-off could be accelerating.

Price of Extinction

There have been five extinction waves in the planet’s history—including the Cretaceous3) event 65 million years ago， which ended the reign of the dinosaurs. The sample polling of animal populations so far suggests that we may have entered what will be the planet’s sixth great extinction wave. And this time the cause isn’t an errant4) asteroid5) or megavolcanoes. It’s us.

Through our growing numbers， our thirst for natural resources and， most of all， climate change—which， by one reckoning， could help carry off6) 20% to 30% of all species before the end of the century—we’re shaping an Earth that will be biologically impoverished. A 2008 assessment by the International Union for Conservation of Nature found that nearly 1 in 4 mammals worldwide was at risk for extinction.

Scary for conservationists， yes， but the question arises: Why should it matter to the rest of us? After all， nearly all the species that were ever alive in the past are gone today. Evolution demands extinction. When we’re using the term extinction to talk about the fate of the U.S. auto industry， does it really matter if we lose species like the Yangtze River dolphin and the golden toad7)， which have effectively disappeared in recent years? What does the loss of a few species among millions matter?

For one thing， we’re animals too， dependent on this planet like every other form of life. The more species living in an ecosystem， the healthier and more productive it is， which matters for us. When we pollute and deforest and make a mess of the ecological web， we’re taking out mortgages on the Earth that we can’t pay back—and those loans will come due. Then there are the undiscovered organisms and animals that could serve as the basis of needed medicines—as the original ingredients of aspirin were derived from the herb meadowsweet8)—unless we unwittingly destroy them first.

Forests razed9) can grow back， polluted air and water can be cleaned—but extinction is forever. And we’re not talking about losing just a few species. In fact， conservationists quietly acknowledge that we’ve entered an age of triage10)， when we might have to decide which species can truly be saved. The worst-case scenarios of habitat loss and climate change show the planet losing hundreds of thousands to millions of species， many of which we haven’t even discovered yet.

To Save the Species， Save the People

So if you believe Earth is more than just a home for 6.7 billion human beings and counting， then you should be scared. But fear shouldn’t leave us paralyzed11). Environmental groups worldwide are responding with new methods to new threats to wildlife. In hot spots like Madagascar and Brazil， conservationists are working with locals on the ground12)， ensuring that the protection of endangered species is tied to the welfare of the people who live closest to them. And as global warming forces animals to migrate in order to escape changing climates， conservationists are looking to create protected corridors that would give the species room to roam. It’s uncertain that any of this will stop the sixth extinction wave， let alone preserve the biodiversity we still enjoy， but we have no choice but to try.

Madagascar is where all the new strategies can be road-tested. Do that right， and you can even turn a profit in the process. In Madagascar， half the revenues from national parks are meant to go to the surrounding communities. In a country as poor as Madagascar—where 61% of the people live on less than $1 a day—it makes sense to give locals an economic stake in preserving wildlife rather than destroying it.

Well-run ecotourism13) can provide support for conservation， but even the best parks might be hard pressed to compete with the potential revenues from logging， poaching14) or mining. Rain forests like those in Madagascar contain billions and billions of tons of carbon; destroying the trees and releasing the carbon not only kills local species but also speeds global warming. Proposals in the global climate negotiations would allow countries to offset some of their greenhouse-gas emissions by paying rain-forest nations to preserve their trees. It’s win-win， with both the climate and the critters15) getting a boost. CI16) and its partners are hiring villagers to plant trees on eroded land， which creates corridors to connect fragmented habitats， may earn carbon revenues and provides needed employment.

Why We Can’t Wait

In a world where hundreds of millions of human beings still go hungry and the global recession has left all but the wealthiest fearing for their future， it’s easy to wonder why we should be concerned about the dwindling of the planet’s biodiversity.

The answer is that we can’t afford not to. The same natural qualities that sustain wildlife—clean water， untainted land， unbroken forests—ultimately sustain us as well， whether we live in a green jungle or a concrete one. But there is an innate value to untrammeled17) biodiversity too—one that goes beyond our own survival. When that is lost， we are irretrievably diminished. “We live on a very special planet—the only planet that we know has life，” says Russell Mittermeier， president of CI. “For me， conservation is ultimately a moral obligation and simply the right thing to do.” That leaves us a choice. We can save life on this special planet， or be its unwitting18) executioner.

大約八千萬到一億年前，馬達加斯加島與印度大陸分離，最終停留在非洲東南海岸。從很多方面來看，馬達加斯加島都像是一個與世隔絕的地球。長期的地理隔離使馬達加斯加成為生物進化論者的樂園，島上各種動物和植物的進化形態都非常獨特。

馬達加斯加島曾經林木繁茂，但自從一千五百多年前人類踏足島上以來，已經有80%以上的原始植被遭到砍伐或焚毀，棲息地變得支離破碎，動物們實際已無家可歸。曾經毫無節制的捕獵已使許多大型物種絕跡，而今天的采礦、伐木和能源開發又對目前尚存的物種構成了新的威脅。

馬達加斯加是生態保護的熱點地區——這種說法表示該地區物種極為豐富，但生態環境岌岌可危。自然資源保護論者估計，目前世界范圍物種滅絕的速度高達歷史上人類迅速繁衍前正常滅絕速度的一千倍。更糟糕的是，這樣的物種消亡還可能會不斷加快。

物種滅絕的代價

在地球歷史上，曾經發生過五波物種大滅絕——包括發生在6，500萬年前的白堊紀滅絕，正是這次滅絕終結了恐龍稱霸的時代。迄今為止對動物種群所做的抽樣調查表明，我們可能已進入地球上第六波物種大滅絕的時期。而此次大滅絕的罪魁禍首既不是脫離軌道的小行星，也不是大型火山噴發。造成這次滅絕的，正是我們人類自己。

人口數量不斷增長，我們對自然資源貪婪索取，再加上最重要的一點，氣候變化——據估計，到本世紀末，氣候變化可能會導致20%到30%的物種滅絕——我們正在使地球變成一個物種枯竭的星球。“國際自然保護聯盟”2008年所作的一份評估報告顯示，全世界約四分之一的哺乳動物都面臨著滅頂之災。

誠然，自然資源保護主義者對此憂心忡忡，但也有人不禁會問:這與我們其他人又有何干呢?畢竟，過去曾出現過的幾乎所有物種如今都已經消失了。有進化就有滅絕。今天我們會用“滅絕”這個詞來形容美國汽車工業的命運，但這和失去白鰭豚和金蟾蜍這些物種(它們最近幾年已銷聲匿跡)又有什么重要關系呢?地球上的物種數以百萬計，損失其中少數一些有什么要緊呢?

首先，我們人類也是動物，與所有其他生命形式一樣，依靠地球而生存。生活在這個生態系統內的物種越多，這個生態系統就會越健康、越繁榮，這對我們人類非常重要。當我們污染環境、砍伐森林、破壞生態網絡的時候，其實就是在向地球借一筆無法償還的債務——而這筆貸款終有一天會到期。其次，還有一些未被發現的生物體與動物，它們可作為某些必需藥物的基本成分——比如阿司匹林的原始成分就來自于繡線菊屬的草藥——但前提是我們沒有在無意識的情況下將它們毀滅殆盡。

森林被毀了還可以重新生長恢復原貌，空氣和水被污染了還可以對其進行凈化處理——可是物種一旦滅絕，就無法挽回。而且我們所說的不是僅僅幾個物種的滅絕。事實上，自然資源保護主義者們默認，我們已經進入了一個必須進行殘酷抉擇的時代，我們可能不得不做出決斷:究竟哪些物種是真的可以被拯救的。面對棲息地的消失和氣候的變化，人們可以預見到最為悲慘的一幕:我們的地球將失去幾十萬甚至幾百萬個物種，而其中許多甚至還不為我們所知。

拯救物種，從“救”人開始

所以如果你認定地球不僅僅只是67億(還在不斷增加)人的家園，那么你就應該感到恐慌。但我們不應因為恐慌而坐以待斃。全球的各個環保組織針對野生動物所面臨的新威脅采取了一些新的應對舉措。在類似馬達加斯加和巴西這樣的熱點地區，自然資源保護主義者與當地居民開展合作，確保瀕危物種的保護與距保護區最近的居民的福祉掛鉤。另外，由于全球變暖，動物們為躲避變化的氣候而被迫遷徙，自然資源保護主義者正在想辦法建立一些生態保護通道，給這些動物提供遷徙空間。然而，誰也不能保證所有這些舉措一定能夠阻止第六波物種大滅絕的到來，更別提保護我們現在尚能樂居其中的含豐富物種的生態環境了，但是我們別無選擇，唯有一試。

所有新的環保戰略都可以在馬達加斯加進行試點。只要方法得當，你甚至可以在此過程中獲得一定的經濟收益。在馬達加斯加，國家公園的一半收入被用于周邊社區建設。馬達加斯加是一個貧困國家——有61%的人每天的生活費不到一美元——在這樣一個國家，給予當地居民一筆經濟獎賞鼓勵他們保護而不是破壞野生動植物，就非常有意義了。

經營有方的生態旅游也可以為環境保護提供支持，但即便是最好的公園，其收益也很難與伐木、偷獵或采礦可能帶來的收入相比。熱帶雨林(如馬達加斯加的熱帶雨林)的碳容量可達數十億噸;摧毀樹林會導致碳的排出，這不僅會滅絕當地物種，而且會加快全球變暖。根據全球氣候談判中提出的一些方案，排放溫室氣體的國家可以付給雨林國家一定的費用，幫助他們保護雨林，以此來抵消自身排放溫室氣體造成的一些不良后果。這是一項雙贏舉措，氣候和生物都可以從中受益。目前，“保護國際”組織及其合作者正在雇用村民在遭到侵蝕的土地上種樹，這樣不僅在支離破碎的棲息地之間建立起一個個生態通道，還有可能產生碳收益，同時又可以為當地人提供他們需要的就業機會。

拯救物種，刻不容緩

在這個世界上仍有數億人食不果腹，眼下的全球經濟衰退令所有人(除了那些超級富翁們)對未來憂心忡忡，在這樣的時候，人們很容易產生疑惑:我們為什么還要去關心地球不斷減少的物種資源呢?

答案是，如果再不關心這個問題，將造成我們無法承擔的后果。野生動植物賴以生存的這些自然條件——干凈的水源、無污染的土地、未被破壞的森林——最終也維持著我們人類的生命，無論我們是生活在綠色叢林還是現代都市。但是，自在的多樣化物種環境還有其自身的價值——不僅僅是為了人類的生存。如果這個價值不復存在，那么人類就會墮入萬劫不復的深淵?！拔覀兩钤谝粋€非常特殊的星球上——我們所知道的唯一一個有生命的星球，”“保護國際”組織的會長拉塞爾·米特邁爾如是說。“對我而言，生態保護說到底是一種道義責任，也是正確的做法。”這就讓我們面臨一個選擇:我們要么選擇拯救這顆特殊星球上的生命，要么選擇成為地球上無知的劊子手。

1. Madagascar [7mAdE5^AskE] n. 馬達加斯加島(非洲島國)

2. proliferate [prEu5lIfEreIt] vi. 增生，擴散

3. cretaceous [krI5teIFEs] adj. 白堊的，白堊紀的

4. errant [5erEnt] adj. 偏離軌道的

5. asteroid [5AstErCId] n. 小游星，小行星

6.carry off:奪去……的生命

7.toad [tEud] n. 蟾蜍，癩蛤蟆

8.meadowsweet [5medEuswi:t] n. 繡線菊屬植物

9.raze [reIz] vt. 夷為平地

10.triage [tri:5B:V] n. [醫]治療類選法(根據緊迫性和救

活的可能性等決定優先治療順序的方法);優先分配

11.paralyze [5pArElaIz] vt. 使癱瘓，使麻痹