金學堂英語的部落格

【聯合報／JUSTIN GILLIS／ESSAY／陳世欽譯】

At the exact moment President Obama was declaring last month that “climate change is a fact,” thousands of drivers in Atlanta were trapped in a grueling winter ordeal, trying to get home on roads that had turned into ribbons of ice.

Mr. Obama’s declaration provoked head-shaking from Congressional climate deniers, and unleashed a stream of mockery on Twitter.

“As soon as he mentioned ‘climate change’ it started snowing on Capitol Hill,” said a post from Patrick J. Michaels at the Cato Institute.

The chortling was predictable, perhaps, but you do not necessarily have to subscribe to an anti-scientific ideology to ask the question a lot of people are asking these days: If the world is really warming up, how come it is so cold?

We are all supposed to know that climate and weather are not the same thing. But we have a tendency to think whatever is happening to us must be happening everywhere.

Scientists refer to global warming because it is about, well, the globe. It is also about the long run.

The entire United States covers less than 2 percent of the surface of the earth. So if the whole country froze solid , that would not affect global temperatures much.

Even this year’s severe winter weather has affected only part of the United States. Alaska has been downright balmy for much of the winter. Likewise, large parts of Russia, Canada and Europe have been bizarrely warm.

A handful of scientists think the 10-degree temperatures in London and the frigid weather in Minneapolis might be a consequence of climate change. They contend the decline of sea ice in the Arctic has destabilized a weather pattern that keeps frigid air bottled up near the pole. That pattern is known as the polar vortex and its boundary is a river of air called the jet stream. When the vortex weakens, the jet stream can creat e zones of extreme heat and cold.

So far, the most interesting fact about th is winter’s Arctic blasts might be how short they have been compared with the past.

The meteorologists Brandt Maxwell, of the National Weather Service in San Diego, and Robert Henson, of the National Center for Atmospheric Research in Boulder, Colorado, have been doing some comparisons.

In the winter of 1976-77, the temperature in Chicago stayed below freezing for 43 days straight . A long stretch this winter was 11 days.

Winters have become so mild over the past 20 to 30 years that a blast of Arctic air feels extraordinary. “If you were 10 years old when this last happened and now you’re 40, that’s quite a chunk of your life,” Mr. Henson said.

In turn, the cold-weather angst may influence how people see the larger issue. Scientists studying human perception have found that our immediate, visceral experience of the world can influence our judgments on related questions. For example, the research shows that on a day perceived as hotter than normal, people are more likely to say that global warming is real, and vice versa.

Fortunately, we are not stuck with human perception alone. We have sophisticated thermometers scattered all over the place. And they are telling us a pretty consistent story. No matter how cold it has been getting in Atlanta, the world really is warming up.

中譯

美國總統歐巴馬上個月宣稱「氣候變遷已經是事實」，而就在同一時刻，亞特蘭大正有數以千計的開車族困在難以忍受的冬季酷寒之中，在已經化為條條冰絲帶的公路上設法把車開回家。

歐巴馬這番宣示使否認氣候變遷的國會人士搖頭，並在推特引起連串嘲諷。

卡托研究所環境政策專家邁克爾斯在推文中說：「他一提到『氣候變遷』，國會山莊就開始下雪。」

這種得意的訕笑或許可以預期，然而即使你未必認同反科學的意識形態，也會提出許多人近年來紛紛提出的以下疑問。

如果世界真的在暖化，又怎麼會冷成這樣？

我們應該都知道氣候與天氣是不同的兩回事。然而我們往往認為，發生在我們身上的事一定也會出現在其他地方。

科學家提到全球暖化主要是因為，它與整個地球有關。它也與長期有關。

美國國土占全球地表面積不到2%。因此，即使全美凍僵，對全球氣溫影響也不大。

就連這個冬季的嚴寒天候也只影響美國部分地區。這個冬季的許多時候，阿拉斯加氣候溫和。俄羅斯、加拿大與歐洲的大片地區也出現異常暖和的天候。

為數不多的一些科學家認為，倫敦的攝氏零下12度低溫與美國明尼蘇達州的嚴寒天候可能是氣候變遷的結果。他們認為，北極海冰融化已使將冷空氣鎖在極區的氣候形態變得不穩定。這種形態名為北極渦旋，邊緣是名為噴射氣流的流動空氣。一旦渦旋減弱，噴射氣流會創造一些極熱與極冷的區域。

截至目前為止，有關這個冬季北極渦旋最耐人尋味的一項事實是，與以往相比，持續的時間非常短。

加州聖地牙哥國家氣象局與科羅拉多州博爾德國家大氣研究中心的氣象專家麥斯威爾及韓生，不斷在做比較。

1976~77年的冬季，芝加哥氣溫維持在攝氏零度以下連續43天。這個冬季最長的也只11天。

過去二、三十年間，冬季變得極為溫和，以致北極冷氣團發威令人覺得非同小可。韓生說：「如果上次發生時你10歲，而你現在40歲，相隔的時間可占了你生命很大一部分。」

嚴寒引起的憂慮可能影響人們對更大課題的看法。研究人類感覺的科學家發現，我們對這個世界直接且切身的經驗足以影響我們對相關問題的判斷。例如，研究顯示，在感覺比往常熱的日子，人們比較可能認為全球暖化確有其事。反之亦然。

所幸我們不是只受限於人類的感覺。精密的溫度計遍布全球各地，告訴我們一則相當一致的故事。無論亞特蘭大變得多冷，這個世界確實是在暖化中。