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Gary Braasch 撰稿08.06.99
以下的景象令人震驚，甚至可說是神秘現象，四組探照燈的光束從我上方向下照射，直到黑暗的水面才消失，海上的霧氣在光束中流動，偶而，冰山也會被照得十分明亮。往左邊看去，一輪朦朧的滿月正好在雲端出現，我站在國家科學基金會(National Science Foundation，簡稱NSF)破冰研究船Nathaniel B. Palmer號的艦橋上，沿著南極半島(Antarctic Peninsula)朝向南極圈(Antarctic Circle)接近。
我第一次讀到有關於這塊南方大陸的事情是在很多年前當我還是個小孩時，而這是我第一次到這裡來。儘管我身為一個自然攝影家，到處旅行並且在北極也花了許多時間，但到了最後我才終於來到南極。多年以來，我的工作讓我從探索自然界的每一個小細節變成現在從事於紀錄氣候改變對全球所造影響的計畫，而這一最近的嘗試便是我為何來此的原因：從我第一次讀到南極一直到現在的四十年當中，南極半島周圍的溫度大約上升了五度，而現在科學家正在研究這對於南極上的冰層及動物造成什麼樣的衝擊。南極對於全球氣候而言就像是一具強而有力的引擎，這裡任何的變化對全球造成的影響都可能可以在這兒預知，甚至直接對全球產生衝擊。
在NSF所資助的研究行程當中有一部份是由地質學家Eugee Domack及其同僚負責，分析由冰層前端崩落部分所採到的一些沉積物樣本，用科學的方法探查千百年前的歷史。這艘船就像是一座300英呎長漂浮在水面上的實驗室，它能對深達數千碼的海水及海洋生物進行採樣，並能帶回50至90呎長的底層沉積物樣本。我在這裡的任務就是拍照，這些照片是要給Discover雜誌的作家Mary Roach用的，她將於十月號的Discover雜誌中專文報導關於Domack的研究。
我們通過南極圈之後的第一站就是Muller 冰層的正面，它位於南極半島西部的最北邊，那裡的海峽中充滿了冰。在那些大約有70英呎高、數百碼長、邊緣近乎垂直般陡峭、巨大且平坦的冰山之間，儘是一些令人難以置信的深藍色大塊純冰、碎冰和冰凍的灰色海水混雜的泥漿。船長小心翼翼地在這些大型冰山間繞行，當船的破冰機向Domack所說一年前曾在冰層前測量過清澈的海水之處前進時，船身便會抖動。但現在船的位置距離冰層仍有數碼之遠，而那些崩落下來的冰凍碎片卻讓船一點也不能再靠近了。
科學家們正逐漸地接近地球的末端，忠實地紀錄氣候變遷所造成的影響、測量、並解釋結果，而他們發現了大麻煩。
在南極州，企鵝及其它鳥類、還有海洋生物都受到環境改變的壓力而正經歷明顯的行為模式改變。在南海太平洋(South Seas)、印度洋(Indian Ocean)、加勒比海(Caribbean)及其它海洋，溫暖化及上升的海平面正危及到珊瑚礁且將會淹沒島嶼。而在各地的高山，尤其在熱帶及喜馬拉雅山脈，冰河持續退縮。各項研究證明了北美及歐洲的蝴蝶分布範圍有向北移動的趨勢。根據長期的觀察紀錄，歐洲鳥類的築巢時間提前，樹也較快長出葉子。在北方森林及北極圈的溫度也正快速上升、永久凍原開始融化，而受到溫暖氣候的影響，許多森林正遭受昆蟲的襲擊而死亡。
格陵蘭的冰帽正在縮減當中，在北極海(Arctic Ocean)中的冰山也是一樣，這兩種現象正是代表了北半球氣候不穩定的嚴重徵兆。
這些及更多的結果，證實了根據實際測量到的全球二氧化碳、甲烷及其它溫室氣體於本世紀中的增加量，所推算出來的氣候變遷的預測。今年三月，Ray Bradley、Michael Mann及Malcom Hughes等三位科學家將地球表面的溫度紀錄追溯到西元1000年，他們不但發現西元1998年是過去1000年來最溫暖的一年，也發現在二十世紀地球表面溫度上升的現象與過去九百年來溫度下降的趨勢剛好相反。
雖然我的任務仍在進行當中，但我已經了解到全球溫暖化的現象並非如我們在一般媒體所聽到黑白兩面的"是"或"不是"的爭論。氣溫確實逐漸地上升且氣候也正在改變，沒有任何強而有力的科學證據反駁這個現象。然而，關於確切的原因我們仍然存在著許多疑問；如何將現在的氣候變遷趨勢跟古時候相比較，它的結果又會是如何。
舉個例子，在南極所採到的深層沉積物樣本顯示在過去十萬年當中，發生過多次的氣候變動，這結果與在格陵蘭冰層中所採的樣本有明顯的關聯性。在Domack的研究當中也發現冰層也曾有形成後又融化的週期。南極溫暖化造成的最大憂慮是南極大陸是全球淡水含量最高的地方，大量的冰帽融化可能會使海平面上升數英呎，雖然這在短時間之內不會發生，但Muller、Wordie及Larsen等冰層大塊地崩落現象也許是一種早期的警告吧。
雖然二十世紀的溫度上升現象並不尋常，雖然其影響遍布各大陸及海洋，但仍然有可能是自然因素而非人類所造成的，對吧？
很抱歉，六月十號出版的Nature期刊刊登了一份英國的研究報告，此報告對於我們排放溫室氣體的責難，要比之前任何一份報告都要來的直接。很不幸的，對於那些等待完整證據的人來說，氣候是很複雜的，而科學研究的進展卻十分緩慢。
我相信我們不能再等待科學上的證據，地球本身已經表現地十分清楚，氣候的變化是越來越快了。植物的分布正在變動，暴風雨越來越大，海岸線持續地被侵蝕，當動植物發現病害消退時，這些病害總是能找到新的居所。不論人們所犯的錯誤程度如何，目前我們有六十億人口居住在這個星球上，並且深受這些變化所影響，我們必須要去適應、度過這些變化，並且盡力減少會讓它惡化的行為。
如果我們沒有這樣做呢？登上Nathaniel B. Palmer號研究船之後，我很自然地想到鐵達尼號(Titanic)、諾雅方舟(Ark)、地球救生船。同時，在南極的夜晚，我注意到那樣的夜晚是多麼地黑，除了狹窄的探照燈光束之外的地方就是所謂的黑暗了。
Gary Braasch為Life、Natural History、 Smithsonian、Audubon及Discover等雜誌作攝影及環境研究工作，他經常報導一些有關於北極、溫帶及熱帶森林、與大沼澤地的自然歷史。
原文與圖片詳見: http://www.gristmagazine.com/grist/
mainevent/braasch080699.stm
版權歸屬 Environment News Service (ENS)，環境信託協會 (陳均輝 譯，李欣哲審校)
中英對照譯稿詳見：http://news.ngo.org.tw/issue/
climate/sub-cc00052301.htm |
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by Gary Braasch 08.06.99
The scene is breathtaking, even mystical. Four searchlight beams arrow down from above me to a vanishing point over dark water. Sea fog sweeps in along the beams and occasionally an iceberg is illuminated. From the left, a small, pale full moon is just showing over the clouds. I am on the bridge of the National Science Foundation research icebreaker Nathaniel B. Palmer, approaching the Antarctic Circle along the Antarctic
Peninsula.
This is my first trip to this southern continent, which I first read about many years ago as a child. It took me an entire career to finally get here, even though I have traveled widely as a nature photographer and spent much time near the other pole, in the arctic. Over the years, my work has taken me from examining the tiny details of nature's design to my current project documenting the climate changes affecting the entire globe. This latest effort is what brings me here: In the 40 years since I first read about Antarctica, the temperature along the peninsula has risen about 5 degrees, and scientists are studying the impact on ice shelves and animals. Antarctica is a powerful engine of world climate and any changes here are likely to preview, or even provoke, a strong effect around the
globe.
As part of a series of NSF-funded research trips, geologist Eugene Domack and his colleagues are analyzing samples of sediments near the disintegrating front of ice shelves, throwing a scientific searchlight on the history of the ice going back hundreds and thousands of years. The ship is a 300-foot-long floating laboratory, with the capability of sampling the sea and its creatures thousands of yards down, and bringing up 50- to 90-foot core samples of bottom sediments. I am here making photographs on assignment for Discover magazine with writer Mary Roach, who will tell the story of Domack's research in an article in the October issue of
Discover.
Our first location after crossing the Antarctic Circle is the face of Muller Ice Shelf, the most northerly shelf on the west side of the peninsula. The fjord is packed with ice. Amid the huge, tabular white icebergs -- sheer ice cliffs that rise to some 70 feet tall and run hundreds of yards long -- are incredible deep blue chunks of pure ice and a slurry of brash and congealing gray water. The captain carefully steers around and between the large bergs. The ship shudders as its icebreaker engines push ahead to a spot where a year before, Domack says, they took measurements in clear blue water right in front of the ice shelf. But now the shelf is still many yards ahead, and the frozen debris of disintegration prevents the ship from moving any
closer.
Scientists are literally going to the ends of the earth to document the ongoing effects of climate change, taking measurements and interpreting the results. And what they are finding is profoundly troubling. Here in Antarctica, penguins, other birds, and ocean creatures, stressed by the alterations in their surroundings, are undergoing notable behavior changes. In the South Seas, Indian Ocean, Caribbean, and elsewhere, warming and rising seas are damaging coral reefs and inundating islands. In mountain ranges everywhere, glaciers are receding, especially in the tropics and the Himalayas. Studies are documenting northward shifts in the ranges of butterflies in western North America and Europe. Birds are nesting earlier and trees are leafing out sooner in Europe, according to long-term observation records. In the boreal forest and arctic regions, temperatures are also rising rapidly, permafrost is thawing, and forests are dying in an insect assault abetted by the warmer climate. The Greenland ice cap is shrinking, as is the ice cover on the Arctic Ocean, both taken as very serious signs of instability in the northern
climate.
These effects and many more are strong confirmation of climate change predictions based on a measurable worldwide rise this century in carbon dioxide, methane, and other greenhouse gases. In March of this year, scientists Ray Bradley, Michael Mann, and Malcom Hughes extended the detailed surface temperature record back to the beginning of this millennium -- not only did they find that 1998 was the warmest year in the past 1,000, but also that the rise in Earth's temperature in the 20th century reversed a 900-year cooling
trend.
My project has just gotten underway, but already I can see that the picture of global warming is not the black or white "is" or "is not" argument we hear in the normal media stories. Climate is warming and changing; there is no strong scientific disagreement. However, there are many questions about the exact causes, how current trends compare with ancient climate changes, and what the results will
be.
In Antarctica, for example, deep cores of sediment show many climate shifts in the past 100,000 years, which correlate broadly with those recorded in Greenland ice sheet cores. It also appears from Domack's studies that there have been previous periods of ice shelf formation and melt-back. The big worry about Antarctic warming now is that the continent contains most of the fresh water on Earth. Mass melting of continental ice caps could raise oceans many feet. That does not appear imminent, but the giant chunks calving off the Muller, Wordie, and Larsen ice shelves are possible early
warnings.
Though the 20th century temperature rise is unusual, though effects are being seen on all continents and oceans, it could still be natural, not caused by human activity, right? Sorry. A British study published in the June 10 issue of Nature lays blame on our greenhouse gas emissions more directly than any previous study. Unfortunately for those waiting for total "proof," climate is complicated and science advances only in
increments.
I believe we can't wait for scientific proof. The Earth is speaking clearly. Climate is changing more and more rapidly. Vegetation zones are going to shift, storms are going to grow more extreme, shorelines are going to erode, diseases are going to find new habitats even as many plants and animals find theirs shrinking. No matter the extent of human culpability, there are 6 billion of us on the planet now, and we will be deeply affected by all these changes. We are going to have to adapt to them, live through them, and reduce activities that make them
worse.
And if we don't? Aboard the Nathaniel B. Palmer, my thoughts turned naturally to the Titanic, to the Ark, to Lifeboat Earth. But also, in the Antarctic night, I noticed how dark it was, just beyond the narrow beam of the searchlights.
Gary Braasch photographs and researches environmental issues for Life, Natural History, Smithsonian, Audubon, and Discover, among other magazines. He has frequently covered the natural history of the arctic, temperate and tropical forests, and the Everglades. |
