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全球暖化的異議份子
- 行徑特異的氣象學家堅稱全球暖化現象不是問題
作者╱葛羅斯曼 ( Daniel Grossman )
譯者╱王瑞香

 
Dissent in the Maelstrom
- Maverick meteorologist Richard S. Lindzen keeps right on arguing that human-induced global warming isn't a problem
By Daniel Grossman
  身為多位美國參議員、智庫以及總統身邊某 些要員的顧問,林德生在當今有關全球暖化的激辯之中,佔有特殊的地位。他是得獎科學家、美國國家科學院(NAS)的會員、麻省理工學院的講座教授,而且在 質疑人類活動是否威脅全球氣候的人當中,他也是最突出而敢言的科學家。直言不諱且言辭犀利的林德生不太能容忍天真幼稚的看法,因此不久前當我在他郊區住家 的車道上停車時,心裡是非常戰戰兢兢的。

 Adviser to senators, think tanks and at least some of the president's men, Richard S. Lindzen holds a special place in today's heated debate about global warming. An award-winning scientist and a member of the National Academy of Sciences, he holds an endowed chair at the Massachusetts Institute of Technology and is the nation's most prominent and vocal scientist in doubting whether human activities pose any threat at all to the climate. Blunt and acerbic, Lindzen ill-tolerates naïveté. So it was with considerable trepidation recently that I parked in the driveway of his suburban home.

  身材魁梧、有濃密的絡腮鬍、頭頂漸禿的林德生引我進到他的起居室,在一支接一支的香菸之間,他想要跟 我強調,他原本並不打算在氣候變遷議題上那樣直言不諱的。一切都得從1988年炙熱的夏天開始。在眾所矚目的美國國會聽證會上,任職於美國NASA哥達德 太空研究中心的物理學家韓森(James E. Hansen)公開表示他的看法,他說,許多科學家「很有信心地」認為,像燃燒石化燃料之類的人類活動正使這世界逐漸暖化。隨後的媒體報導令林德生感到震 驚。他回憶道︰「我覺得澄清這件事很重要,也就是說,這門科學還在最初的起步階段,我們沒有什麼基礎可形成共識,卻有極多理由抱持懷疑態度。」他原本以為 對氣候的爭論將有一、兩個月會是大眾的焦點,結果卻持續了超過10年之久。他談到早期的想法時說:「那時我確實感到一種道德上的責任,不過現在已經陷入難 以脫身的角色了。」

  A portly man with a bushy beard and a receding hairline, Lindzen ushered me into his living room. Using a succession of cigarettes for emphasis, he explains that he never intended to be outspoken on climate change. It all began in the searing summer of 1988. At a high-profile congressional hearing, physicist James E. Hansen of the NASA Goddard Institute for Space Studies went public with his view: that scientists knew, "with a high degree of confidence," that human activities such as burning fossil fuel were warming the world. Lindzen was shocked by the media accounts that followed. "I thought it was important," he recalls, "to make it clear that the science was at an early and primitive stage and that there was little basis for consensus and much reason for skepticism." What he thought would be a couple of months in the public eye has turned into more than a decade of climate skepticism. "I did feel a moral obligation," he remarks of the early days, "although now it is more a matter of being stuck with a role."

  或許這只是一種角色,但林德生仍然興致勃勃地扮演它。他攻擊的範圍很廣,包括電腦模型、大氣物理學以及有關古氣候的研究。他的觀點源源不斷地出現在國會作證、報紙言論版及公共場合。2001年稍早,他還為美國總統布希的內閣上了一堂有關氣候變遷的課。

  It may be just a role, but Lindzen still plays it with gusto. His wide-ranging attack touches on computer modeling, atmospheric physics and research on past climate. His views appear in a steady stream of congressional testimonies, newspaper op-eds and public appearances. Earlier this year he gave a tutorial on climate change to President George W. Bush's cabinet.

   要釐清林德生的看法和其他科學家的不同之處並不容易,因為他對其他許多人認為已經解決的問題多所質疑。他強烈辯駁2000年春季出爐的政府間氣候變遷研 究小組(IPCC)報告的結論(一般認為這是科學界對於氣候變遷的決定性結論),以及最近一份NAS審視該小組結論的報告;林德生是IPCC報告其中一章 的主要作者,也是NAS報告的作者。然而,根據他的說法,美國的主導科學家(他說這些人也同意他的觀點)寧可不蹚氣候變遷的渾水:「一般科學家不會想要捲 入那種壓力之中。」美國國家大氣研究中心著名的氣候科學家威格里(Tom M. L. Wigley)說,頂尖研究者保持緘默「顯然是不對的」。而他指出,是「世界上最優秀的人」促成了這本IPCC報告。

   It's difficult to untangle how Lindzen's views differ from those of other scientists because he questions so much of what many others regard as settled. He fiercely disputes the conclusions of this past spring's report of the Intergovernmental Panel on Climate Change (IPCC)—largely considered to be the definitive scientific assessment of climate change—and those of a recent NAS report that reviewed the panel's work. (Lindzen was a lead author of one chapter of the IPCC report and was an author of the NAS report.) But, according to him, the country's leading scientists (who, he says, concur with him) prefer not to wade into the troubled waters of climate change: "It's the kind of pressure that the average scientist doesn't need." Tom M. L. Wigley, a prominent climate scientist at the National Center for Atmospheric Research, says it is "demonstrably incorrect" that top researchers are keeping quiet. "The best people in the world," he observes, have contributed to the IPCC report.

  林德生同意IPCC以及 大多數其他氣候科學家的看法,即過去100年來,世界暖化了0.5℃;他也同意人類活動使大氣中的二氧化碳含量增加了約30%。但就這些事實之間的關聯性 而論,林德生的看法便與其他人分道揚鑣了。他並不是說人類對氣候全無影響,他也承認「人類確有影響」,不過人類對環境的衝擊充其量也不過像「一隻蝴蝶收起 牠的雙翅一般」。

  Lindzen agrees with the IPCC and most other climate scientists that the world has warmed about 0.5 degree Celsius over the past 100 years or so. He agrees that human activities have increased the amount of carbon dioxide in the atmosphere by about 30 percent. He parts company with the others when it comes to whether these facts are related. It's not that humans have no effect at all on climate. "They do," he admits, though with as much impact on the environment as when "a butterfly shuts its wings."

  IPCC報告指出,「過去50年來所觀察到的暖化現象大多數」是人類引起的。該報告說,20世紀的氣溫急速上升,超過了過去 1000年來地球曾經歷的所有氣候變化。美國維吉尼亞大學地質學家,也是IPCC報告中有關古氣候一章的主要作者曼恩(Michael E. Mann)說,這個升高現象「與自然的變異性不一致」。林德生則質疑他們決定過去歷史氣溫的方法,因而不接受這個分析結果。他主張,就過去1000年的頭 600年而言,研究者只利用樹木的年輪來估計氣溫,而且樹輪只取自四處不同的地點而已。他認為,用樹輪來判斷氣溫的做法錯得離譜。

   The IPCC report states that "most of the observed warming over the last 50 years" is of human origin. It says that late 20thcentury temperatures shot up above anything the earth had experienced in the previous 1,000 years. Michael E. Mann, a geologist at the University of Virginia and a lead author of the IPCC's past-climate chapter, calls the spike "a change that is inconsistent with natural variability." Lindzen dismisses this analysis by questioning the method for determining historical temperatures. For the first 600 years of the 1,000-year chronology, he claims, researchers used tree rings alone to gauge temperature and only those from four separate locations. He calls the method used to turn tree-ring width into temperature hopelessly flawed.

  當我就林德 生的批評向曼恩請教時,曼恩大吃一驚,指之為「信口雌黃」、「無憑無據」。仔細檢視IPCC報告可以看出,例如,樹木並非唯一的資訊來源,冰芯(ice core)亦協助重建過去1000年中頭600年的氣溫變化,而且樹木樣本取自分散全球各地12個區域的34處不同地點,而不是四處。

  Mann was flabbergasted when I questioned him about Lindzen's critique, which he called "nonsense" and "hogwash." A close examination of the IPCC report itself shows, for instance, that trees weren't the sole source of data—ice cores helped to reconstruct the temperatures of the first 600 years, too. And trees were sampled from 34 independent sites in a dozen distinct regions scattered around the globe, not four.

  古氣候 並非唯一看法有分歧的議題。林德生還說,沒有什麼理由值得我們為未來擔心,其樂觀看法的關鍵在於一個叫做「氣候敏感度」(climate sensitivity)的參數。這個變數是指,當空氣中的二氧化碳含量增加為工業時代前的兩倍時,預期中全球氣溫增加的情形;而目前地球上二氧化碳的含 量已經快達到目標值的1/3了。當IPCC和NAS估計氣候敏感度約為1.5~4.5℃之間時,林德森堅持只有0.4℃左右。

  Past climate isn't the only point of divergence. Lindzen also says there is little cause for concern in the future. The key to his optimism is a parameter called "climate sensitivity." This variable represents the increase in global temperature expected if the amount of carbon dioxide in the air doubles over preindustrial levels—a level the earth is already one third of the way toward reaching. Whereas the IPCC and the NAS calculate climate sensitivity to be somewhere between 1.5 and 4.5 degrees C, Lindzen insists that it is in the neighborhood of 0.4 degree.

  IPCC和NAS是在納入了「正回饋機制」之後,得出較高的溫度範圍,例如較暖的氣溫極可能縮減地球上雪與冰的覆蓋範圍,使得這行星對於熱能的反射力較弱,因而加速暖化,而且恐怕還會增加水的蒸發作用。事實上,水蒸氣是大氣中主要的熱吸收體。

  The IPCC and the NAS derived the higher range after incorporating positive feedback mechanisms. For instance, warmer temperatures will most likely shrink the earth's snow and ice cover, making the planet less reflective and thus hastening warming, and will also probably increase evaporation of water. Water vapor, in fact, is the main absorber of heat in the atmosphere.

   但是,林德生在2001年5月告訴美國參議院商務委員會,這種正回饋「既無經驗上亦無理論上的基礎」。這位科學家說,當今的效應是負回饋作用,而不是正 回饋。他所提出的一個假設是,增加的暖化作用確實使得高層大氣的某些部份乾掉了,而水蒸氣一旦減少,接下來便會使得暖化現象緩和下來。哥達德太空研究中心 的韓森說,由於林德生提出這樣的可能性,他可說是「為氣候的討論行了大善」。然而韓森趕緊補充道:「我非常確定,他提出的這個基礎評論,即氣候模型高估了 氣候敏感度,是錯誤的。」

  But such positive feedbacks "have neither empirical nor theoretical foundations," Lindzen told the U.S. Senate commerce committee this past May. The scientist says negative, not positive, feedback rules the day. One hypothesis he has postulated is that increased warming actually dries out certain parts of the upper atmosphere. Decreased water vapor would in turn temper warming. Goddard's Hansen says that by raising this possibility Lindzen "has done a lot of good for the climate discussion." He hastens to add, however, "I'm very confident his basic criticism—that climate models overestimate climate sensitivity—is wrong."

  2001年3月,林德生發表了他說可能是他曾寫過「最重要的」論文,討論水蒸氣的負回饋作用。在文章裡,他推斷暖化 現象會減少熱帶地區的雲量。雲量是一個複雜的主題,取決於瞬息萬變的各種因素,使得雲會有冷卻作用(藉著將陽光反射回太空)或暖化作用(藉著接收來自地球 的熱)。林德生說,熱帶地區雲量降低會產生顯著的全面冷卻效果,因而具有穩定的負回饋作用。

  In March, Lindzen published what he calls "potentially the most important" paper he's written about negative feedback from water vapor. In it, he concludes that warming would decrease tropical cloud cover. Cloud cover is a complicated subject. Depending on factors that change by the minute, clouds can cool (by reflecting sunlight back into space) or warm (by trapping heat from the earth). Lindzen states that a reduction in tropical cloudiness would produce a marked cooling effect overall and thus serve as a stabilizing negative feedback.

  但是,有三個研究小組指出林德生的論文有瑕疵,例 如他的研究所根據的資料是取自熱帶雲層的衛星影像。NASA蘭利研究中心的威利基(Bruce A. Wielicki)認為,衛星影像並不能代表整個熱帶地區的情形。在一篇刊登於《氣候學期刊》的文章裡,威利基和他的小組推斷,總的說來,如果收集來自不 同衛星的資料會發現,較溫暖的熱帶雲會有些許的暖化作用,而非冷卻作用。

  But three research teams say Lindzen's paper is flawed. For example, his research was based on data collected from satellite images of tropical clouds. Bruce A. Wielicki of the NASA Langley Research Center believes that the images were not representative of the entire tropics. Using data from a different satellite, Wielicki and his group conclude, in a paper to appear in the Journal of Climate, that, on balance, warmer tropical clouds would have a slight heating, not a cooling, effect.

  回顧過去10年的氣候科學,許多研究者認為電腦模型已有進步,在估算 古氣候時已經比較精確,不確定性也減少了。不過林德生可沒有這麼樂觀,在他看來,全球暖化這件事還是和他1988年開始熱誠投入時一樣缺乏證據。他堅稱, 氣候研究「受到政治辭令嚴重污染,有關證據還是極度薄弱」。對林德生而言,地球顯然會好好照顧它自己的

   Looking back at the past decade of climate science, many researchers say computer models have improved, estimates of past climate are more accurate, and uncertainty is being reduced. Lindzen is not nearly so sanguine. In his mind the case for global warming is as poor as it was when his crusade began, in 1988. Climate research is, he insists, "heavily polluted by political rhetoric, with evidence remaining extremely weak." To Lindzen, apparently, the earth will take care of itself (please watch the movie  "【The Day After Tomorrow】").


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