評論
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Science and Technology
科技
Climate and the solar cycle
氣候與太陽周期
Chilling out in the winter sun
冬日下的冷噤
Stratospheric changes can lead to nasty cold snaps
平流層變化引起討厭的嚴寒
THOSE unconvinced-and those seeking to unconvince others-of the reality of man-made global warming often point to the changeable behaviour of the sun as an alternative hypothesis.
那些自己不信和那些游說他人不要相信人類活動導致全球變暖的人，常常將其歸咎于太陽活動多變。
A new study showing how the severity of winters in Europe, and warming in the Arctic, might be linked to changes in solar activity might seem to add to this case.
一項新的研究似乎為此提供了新證據：該研究顯示歐洲冬日的嚴寒以及北極地區的溫暖也許真與太陽活動有關。
In itself, it does not, for the heat (or, rather, the cold) in question is being redistributed, not retained.
就研究本身而言，它并不能提供新的證據，因為所提到的熱能（或者是寒氣）是被重新分配而不是滯留固定的。
But it does point to two other lessons about climate change: that hard data on the factors which affect it are sometimes difficult to come by;
但它的確指出了關于氣候變化的另外兩個問題：一是有時候很難獲得影響氣候變化的因素的切實數據；
and that computer models of the climate can be quite impressive tools for working out what is going on.
二是計算機氣候模型在探究氣候現象方面是十分強大的工具。
The sun's activity waxes and wanes on an 11-year cycle, and over this cycle the amount of ultraviolet (UV) light the sun emits changes a lot more than does the total amount of energy.
太陽活動的盛衰以11年為一個周期，在一個周期內，太陽放射的紫外線的變化幅度要比其放射的能量的變化幅度要大得多。
The stratosphere, the part of the Earth's atmosphere which does most to absorb UV, might thus be expected to particularly sensitive to the cycle.
因此，地球大氣中吸收最多紫外線的平流層也許對這一周期變化最為敏感。
In a paper just published in Nature Geoscience, Sarah Ineson of Britain's Meteorological Office and her colleagues compared the way that the Met Office's new and putatively improved climate model dealt with winters at times of high UV and at times of low UV, using data on the amount of ultraviolet the sun gives off that were collected by a satellite called SORCE.
《自然地球科學》雜志剛剛發表的一篇論文上，英國氣象局的莎拉?伊內森和她的同事們利用SORCE（太陽輻射和氣候試驗）衛星收集的太陽放射的紫外線數據，對比了氣象局新建立的改良版氣候模型對于紫外線峰值年與低谷年的冬天的處理方式。
Dr Ineson found that at low UV levels the stratosphere in the tropics was cooler, because there was less UV for it to absorb, which meant the difference in temperature between the tropical stratosphere and the polar stratosphere shrank.
伊內森博士發現，熱帶平流層在紫外線低谷年的溫度偏低，因為可吸收的紫外線較少，這就使得熱帶平流層與極地平流層的溫差縮小。
That changed the way the atmosphere circulated, and as those changes spread down into the lower atmosphere they made it easier for cold surface air from the Arctic to come south in winter, freezing chunks of northern Europe.
這一溫差變化會改變大氣循環的方式，而低層大氣循環方式的改變讓冬天北極冷空氣更易南下，冰凍北歐大片地區。
These conditions looked similar to those seen in the past two cold European winters-which occurred at a time of low solar activity.
這些狀況與歐洲上兩次均發生在太陽活動沉靜期的嚴酷寒冬的狀況十分相似。
The Arctic itself, in models and in real life, was warmer than usual, as were parts of Canada.
這種狀況下，無論在氣候模型中還是現實中，北極和加拿大部分地區都比平常要溫暖。
In contrast, northern Europe, swathes of Russia and bits of America were colder.
相比之下，北歐、俄羅斯大部分地區以及美國小部分地區則比平常要冷。
Why had this solar effect not been seen before?
為何太陽在這方面的影響之前未被發現？
To some extent it had.
某種程度上說，的確有前人初見其端倪。
Earlier modelling of a period of prolonged low solar activity in the 17th and 18th centuries showed similar patterns.
早前一個的反映十七、十八世紀偏長的太陽活動低迷期的模型顯示了類似的氣候變化模式。
That models of today's climate had not was, in part, because they used much lower estimates of the amount of UV variation over the solar cycle than those derived from the SORCE data, the most precise to be taken from a satellite looking at the sun.
今日的模型未能發現這一影響的部分原因是，與SORCE衛星收集的最精確數據所計算衍生的數值相比，這些模型對太陽活動周期內紫外線值的變化幅度估計過低。
It may just be that working with more realistic data made the model work better.
也許就是更切實的數據讓這些模型做得更好。
This does not mean the question is settled.
但問題并沒有解決。
Some scientists suspect the SORCE data may be exaggerating the sun's variability, and if they were revised the link might go away.
有些科學家認為SORCE衛星的數據有夸大太陽活動變化幅度的嫌疑，如果將數據加以修正，那么太陽活動與氣候的所謂聯系很可能也不復存在。
There are other theories around seeking to explain the recent cold winters, too.
還有其他一些理論也致力于找出近期嚴酷寒冬發生的原因。
Improving predictions of future cold winters on the basis of this work, as the researchers say they would like to do, may thus prove hard.
如研究人員所說，基于這項工作的成果，他們就有可能對寒冬做出更精準的預測。
But though global warming has made people look to models as predictors of the future, that is not their strongest suit.
盡管全球變暖使人們將氣候模型視為預測工具，但這可不是它們最強大的地方。
Something they can do much better is look at what happens when a variable such as UV is altered, compare that with the data, and thus gain insight into the mechanisms by which climate works.
它們更精于研究當紫外線等某一變量變化時發生的情況，并將其與已有數據進行比較，從而了解氣候運作機制。
This new research provides a good example of what such an approach can achieve.
此項新研究很好地給我們展現了這一方法的潛能。
