蒸騰的太平洋 海水升溫成因複雜

Hurricane Patricia was a surprise. The eastern Pacific hurricane strengthened explosively before hitting the coast of Mexico, far exceeding projections of scientists who study such storms.

颶風“帕特里夏”(Patricia)讓人比較意外。在襲擊墨西哥海岸之前，這場出現在東太平洋海域的颶風勢頭驟然增強，遠超出了研究此類風暴的科學家們的預料。

And while the storm’s strength dissipated quickly when it struck land, a question remained. What made it such a monster?

雖然登陸之後，它的力量迅速消散，但有一個疑問依然存在，即這場勢如怪獸的颶風是由什麼引起的？

Explanations were all over the map, with theories that included climate change (or not), and El Ni.

相關解釋五花八門，其中包括氣候變化（或氣候不變）和厄爾尼諾現象等各種理論。

But the answer is more complicated. The interplay of all the different kinds of warming going on in the Pacific at the moment can be difficult to sort out and, as with the recent hurricane, attributing a weather event to a single cause is unrealistic.

但答案卻更爲複雜。目前太平洋上有各種不同的變暖現象在相互作用，難以釐清。就最近這場颶風而言，將一個氣象事件歸於某個單獨的因素是不現實的。

Gabriel Vecchi, head of the climate variations and predictability group at the geophysical fluid dynamics laboratory of the National Oceanic and Atmospheric Administration in Princeton, N.J., likened the challenge to the board game Clue.

布里埃爾·韋基(Gabriel Vecchi)將這項挑戰比作桌遊“妙探尋兇”(Clue)，他是位於新澤西州普林斯頓市的美國國家海洋與大氣管理局（National Oceanic and Atmospheric Administration，簡稱NOAA）地球物理流體動力學實驗室氣候變化和可預測性小組的負責人。

“There’s all these suspects, and we have them all in the room right now,” he said. “The key is to go and systematically figure out who was where and when, so we can exclude people or phenomena.” Extending the metaphor, he noted that criminal suspects could work together as accomplices, and there could be a character not yet known. And, as in all mysteries, “You can have a twist ending.”

“有各種各樣的疑犯，目前都在這個屋子裏，”他說。“關鍵在於系統地搞清楚每個人什麼時候都出現在什麼地方，這樣我們才能排除不是兇手的人，或說排除不是影響因素的現象。”他還表示，拿這個比喻繼續推演，幾名疑犯可能會聯合作案，可能還有你不瞭解的角色存在。而且，就像在所有的迷案中一樣，“結尾有可能出現劇情大逆轉。”

At the moment, the world’s largest ocean is a troublesome place, creating storms and causing problems for people and marine life across the Pacific Rim and beyond. A partial list includes the strong El Ni system that has formed along the Equator, and another unusually persistent zone of warm water that has been sitting off the North American coast, wryly called “the Blob.”

全世界最大的海洋目前成了一個比較棘手的地方，它製造多場風暴，給居住在環太平洋區域的人們帶來各種問題，也影響了這一區域的海洋生物。這些問題包括沿赤道形成的強厄爾尼諾氣候，和在北美沿岸海域持續存在的異常暖水區域，後者被人戲稱爲“溫水區”(the Blob)。

And a longer-term cycle of heating and cooling known as the Pacific Decadal Oscillation may be switching from a cooling phase to a warming phase. On top of all that is the grinding progress of climate change, caused by accumulation of greenhouse gases generated by human activity.

還有一種被稱爲“太平洋十年濤動”(Pacific decadal oscillation)、週期更長的海水冷熱更替現象，現在可能正從寒冷期轉入溫暖期。除了這些，還有一個最重要的因素，那就是由人類活動產生的溫室氣體不斷累積而引發的、無休無止的氣候變化。

Each of these phenomena operates on a different time scale, but for now they appear to be synchronized, a little like the way the second hand, minute hand and hour hand line up at the stroke of midnight. And the collective effects could be very powerful.

這些現象各有自己的運轉節奏，但目前它們似乎實現了同步，有點像秒針、分針和時針在午夜重合。而且由此形成的集體效應非常強大。

Although they interact with one another, each of these warming events is being blamed for specific problems.

儘管他們相互作用，但每個變暖事件都被歸爲某些特定問題的起因。

“The Blob” has been associated, among other effects, with the unusually dry and warm weather in the western United States. Out in the ocean, the nutrient-poor warmer waters of the Blob — about four degrees Fahrenheit higher than average — are disrupting the food web of marine life. Some species of fish are showing up where they are not expected, including tropical sunfish off the Alaska coast, and an unusual number of emaciated sea lion pups and Guadalupe fur seals are being found stranded on California shores.

溫水區被認爲與許多問題有關，其中之一是美國西部出現的不尋常的乾燥溫暖天氣。它所在的海域營養貧乏、溫度高於正常的海水——大概比平均溫度高4華氏度——正在擾亂海洋生物的食物鏈。有些魚類出現了它們本不會出現的地方，比如阿拉斯加海岸附近出現了熱帶太陽魚，加州海岸上則有數目異乎尋常的贏弱海獅幼崽和瓜達盧普海豹擱淺岸邊。

The warm water has also been linked to unprecedented harmful algal blooms along the coasts that have rendered shellfish toxic and shut down shellfish fisheries in Washington, Oregon and California. “A single clam can have enough toxins to kill a person,” said Vera L. Trainer, the manager of the marine biotoxin program at NOAA’s Northwest Fisheries Science Center in Seattle. Officials also ordered the largest closure of the state’s Dungeness crab fishing.

海水變暖還被認爲與海岸線出現的前所未有的有害藻類大量繁殖現象有關，它導致甲殼類水生動物中毒，使華盛頓州、俄勒岡州和加州關停了貝類水產養殖場。“一個蛤蜊所含的毒素就足以致人死亡，”位於西雅圖的NOAA西北漁業科學中心的海洋生物毒素項目負責人薇拉·L·特雷納(Vera L. Trainer)說。官員還下達了該州規模最大的一次鄧傑內斯蟹禁捕令。

“It’s really worrisome,” Dr. Trainer added. “If this is a single event that then goes away and we can forget about it down the road, it’s O.K. If it’s a window into the future, it’s not a good future.”

“這真的很讓人擔憂，”特雷納博士接着說。“如果這是一個單一事件，之後就會消失，人們可以忘記它，倒也還好。但如果它是面向未來的一扇窗，那就不妙了。”

The unusually strong El Ni weather pattern, in which the ocean’s surface warms and releases immense amounts of heat into the atmosphere, has drawn more attention — in part because it tends to bring heavy rain to Southern California, which is amid an intense drought, and cooler temperatures and rain across the southern United States during the winter and potentially into the spring. (The northern band of the country tends to have somewhat warmer and drier conditions.) But El Ni’s effects are felt across the planet, and this one has been linked to drought in Australia and enormous peat fires in Indonesia.

厄爾尼諾氣候異常強大，它會使海洋表面變暖，並向大氣中釋放巨大的熱量，這種氣候現象已經引起更多的關注，部分原因在於，它會在冬季，甚至一直到春天，給正處於劇烈乾旱之中南加州帶來強降雨，並使整個美國南部都有持續降雨和更低的氣溫。（美國北部地區則可能會更溫暖和更乾燥。）但是，厄爾尼諾氣候的影響遍及全球，這一次它已經被與澳大利亞的乾旱和印尼的泥炭土叢林大火災聯繫了起來。

The other large force at work, the Pacific decadal oscillation, is a long period — sometimes, as the name implies, spanning decades — of relatively cooler or warmer water. Since about the year 2000, the oscillation has been in a cool state, which many climate scientists say has allowed the ocean to soak up a great deal of the heat generated by greenhouse gases as part of climate change.

另一種正在產生影響的巨大力量是太平洋十年際濤動，它是相對更冷或更熱的海水期交替出現的現象，週期比較長，有時候如它的名字所顯示的，會延續數十年。大約從2000年開始，它一直處於寒冷週期，許多氣候科學家認爲這使得海洋吸收了很多由溫室氣體產生的熱量，而溫室氣體是氣候變化的一部分。

This, in turn, may have kept global average surface temperatures from rising. Climate scientists have called that condition the warming hiatus, and those who deny the overwhelming scientific consensus on warming have used the hiatus to raise doubts about whether climate change exists.

這反過來可能避免了全球地表平均溫度的上升。氣候科學家們稱這種情況是“變暖間歇”(warming hiatus)，而那些否認氣候變暖這個壓倒性科學共識的人，則利用這種間歇來質疑氣候變化是否存在。

Now, however, the oscillation appears to be entering a warming phase, said Gerald A. Meehl, a senior scientist at the National Center for Atmospheric Research, and strong El Ni猀 tend to nudge the cycle into a new phase. So the oscillation and El Ni “can all add together to give you a really big shift” toward warming over all.

然而，國家大氣研究中心(National Center for Atmospheric Research)資深科學家傑拉德·A·米爾(Gerald A. Meehl)表示，現在波動似乎正在進入變暖期，而且強大的厄爾尼諾現象也可能會推動相關循環進入新階段。於是，波動和厄爾尼諾“可能共同發揮作用，帶來真正的大轉折”，全面轉向升溫變暖。

“That’s going to provide a bigger boost to a global warming system,” he said. “These things will add together.” Already, 2015 is on track to be the hottest year in the historical record.

“這將進一步推動全球變暖的系統，”他說。“這些因素將疊加在一起。”目前，2015年有望成爲有歷史記錄以來最熱的一年。

Climate change could nudge all of the interacting cycles of ocean heat and cold. Scientists are still trying to determine its effect on hurricanes, though it is widely believed that because warm ocean water provides the energy for hurricanes, the more powerful storms will grow even more potent over time.

氣候變化可能會推動海洋中所有的熱冷互動循環。科學家仍在試圖確定其對颶風的影響，但人們普遍認爲，由於溫暖的海水會爲颶風提供能量，已然加強的風暴還會隨着時間的推移而愈發強烈。

Whether there is a clear and detectable human-caused component to today’s cyclone activity is harder to prove, said Thomas R. Knutson, a research meteorologist with NOAA’s geophysical fluid dynamics laboratory at Princeton. “We don’t expect to necessarily be able to detect these changes at this time,” he said.

氣象學家托馬斯·R·紐森(Thomas R. Knutson)表示，難以證明如今的氣旋活動，是否有明確且能察覺到的人爲因素。紐森供職於NOAA在普林斯頓大學的地球物理流體動力學實驗室。他說，“我們並不指望一定能在這個時候觀察到這些變化。”

While no individual weather event can be linked to climate change, the continued warming already appears to be increasing the potential strength of storms, said Kerry Emanuel, a hurricane expert at the Massachusetts Institute of Technology. Whether the storms reach their full potential depends on other factors, he said. Statistically, however, there are too few storms to show that the stronger hurricanes are being caused by climate change yet.

麻省理工學院(Massachusetts Institute of Technology)研究颶風的專家克里·伊曼紐爾(Kerry Emanuel)表示，雖然無法將任何一個單獨的天氣事件和氣候變化聯繫在一起，但持續變暖似乎增強了風暴的潛在強度。他說，風暴能否達到最大強度取決於其他因素。但從統計數據看，現有的風暴次數還太少，不足以顯示颶風強度的提高是由氣候變化引起的。

One phenomenon appears to be the result of a combination of El Ni, the Blob and climate change. NOAA this year announced that the world was in the midst of only the third global coral bleaching event ever recorded. Severe bleaching can lead to the death of reefs, and the loss of habitat for marine life and shoreline protection from storms. The current event began in 2014 in the Pacific and has persisted into this year, with the Blob’s effects being felt most keenly near Hawaii, where the western tail of that large patch of warmed water extends.

有一種現象似乎是厄爾尼諾、太平洋“溫水區”和氣候變化綜合作用的結果。NOAA今年宣佈，世界目前處在史上第三次全球珊瑚白化潮之中，嚴重的白化會導致珊瑚礁死亡，讓海洋生物由此失去棲息地，也使海岸線失去阻擋風暴的防護牆。發生在太平洋裏的這次白化潮始於2014年，一直延續到今年，而受“溫水區”影響最大正是靠近夏威夷羣島的區域，那裏是“溫水區”帶來的大片溫暖海水延伸的西部邊緣地帶。

“This is absolutely the worst that they have ever seen,” said C. Mark Eakin, the coordinator of NOAA’s Coral Reef Watch. “It’s only the third time they’ve seen mass coral bleaching in Hawaii; the last time was last year.” And because El Ni events stretch from one year’s winter into the next spring, “we’re very likely to see the bleaching that’s going on this year go on into 2016 and even be worse in 2016,” he said.

“這絕對是我見過的最糟糕的情況，”NOAA全球珊瑚礁觀測網絡(Coral Reef Watch)的協調員C·馬克·埃金(C. Mark Eakin)說。“夏威夷區域出現大規模珊瑚白化，這還只是第三次，上一次是在去年。”而且，因爲厄爾尼諾現象通常會從一年的冬季延續到下一年的春季，“我們很可能會看到這次白化潮持續到2016年，甚至在2016年變得更加嚴重，”他說。

A warmer Pacific also means higher seas at the United States coastline, because warm water expands and the general winds that flow from west to east will push water against the shore. That can add to an increase in what William Sweet, a NOAA oceanographer based in Maryland, calls nuisance flooding in low-lying coastal areas.

太平洋變暖，也意味着美國海岸線的海平面會升高，因爲水溫升高體積就會膨脹，自西向東的整體風向會把海水吹向海岸。那會提高低海平面區域發生威廉·斯威特(William Sweet)所說的“海水漫溢災害”的機率。斯威特是NOAA駐馬里蘭州海洋學家。

Even a general increase of a half a foot from El Ni can, when combined with storms, cause a pronounced increase in such flooding, he said, adding that San Francisco could go from an average 12 days of nuisance flooding to 21 this year, and La Jolla, Calif., from six to 10.

他表示，即便海平面只因厄爾尼諾現象總體升高半英尺，當同時受到風暴因素影響時，也會顯著增加發生此類海水漫溢災害的機率。他還指出，舊金山過去每年平均遭遇12天的海水漫溢，今年有可能增加到21天，加州的拉霍亞市區則可能從過去的6天增加到10天。

Nicholas A. Bond, a research meteorologist at NOAA’s cooperative institute at the University of Washington who gave the Blob its name, said that climate change could make El Ni conditions more common. “That would just have monstrous implications,” he said. And though developed-world nations like the United States could take measures to adapt to the changing conditions, “It is going to be a different place,” he said.

供職於NOAA在華盛頓大學(University of Washington)的合作機構的氣象學家尼古拉斯·A·邦德(Nicholas A. Bond)表示，氣候變化可能會讓厄爾尼諾現象變得更加常見。“溫水區”這一現象就是邦德命名的。“那會帶來各種可怕的後果，”他說。儘管美國等發達國家可以採取措施適應變化的氣候情況，“但這裏將成爲另外一種樣子，”他說。

Despite all the current dark clouds over the Pacific, literal and metaphorical, Dr. Bond managed to spot a silver lining.

雖然目前太平洋上佈滿了陰雲——這既是現實，也是比喻——邦德博士設法爲我們帶來了一絲希望。

The confluence of problems can serve as a “wake-up call,” and a harbinger of climate change, he said. “We have a real chance with this kind of event to see what’s going to happen, and show folks, ‘Hey, this is the consequence of messing around with the climate.’ ”

他說，這些問題合在一起，可以看做一種“警示”，是氣候變化的前兆。“有了這類事件，我們得以真正有機會了解未來會發生些什麼，可以跟人們說，‘看吧，這就是破壞氣候帶來的後果。’”