去年圣誕節(jié)，圣誕老人一定是穿著T恤和短褲往雪橇上裝禮物。北極點(diǎn)的溫度攀升至冰點(diǎn)，而正常溫度應(yīng)該是零下二十華氏度。今天出國(guó)留學(xué)網(wǎng)小編就給大家介紹一下托福聽力科學(xué)美國(guó)人60秒 北極出現(xiàn)反滾雪球效應(yīng)。
This is Scientific American — 60-Second Science. I＇m Julia Rosen.
Got a minute？
Last Christmas， Santa Claus must have been loading his sleigh in a t-shirt and shorts. Temperatures at the North Pole crept up toward the freezing point when they should have been minus twenty Fahrenheit.
The heat wave was the latest in a series that have swept over the Arctic in recent winters. Climate change has caused steady warming in the region. But it has also helped supercharge these extreme events， which scientists say are tied to storms that spiral north out of the Atlantic.
＂These winds actually pick up a lot of heat and moisture.＂
Vladimir Alexeev， a climate scientist at the University of Alaska Fairbanks.
＂And the atmosphere carries all this extra moisture and heat to the central Arctic， which results in [a] warmer and moister atmosphere.＂
Which then warms the surface.
Alexeev says the heat ferried north by these storms helps slow the growth of sea ice in winter—causing it to be about 15 centimeters thinner by the end of the season. And thinner ice may have a harder time surviving the summer.
But while the impact of these storms has grown in recent decades， the storms themselves are not happening more often， Alexeev says.
＂An important piece of information is that the frequency of those storms is not changing. What＇s changing is the area of open water in those regions.＂
As the Atlantic Ocean has warmed up， the amount of sea ice around Scandinavia and Siberia in winter has decreased. So now， instead of passing over an ice-capped ocean， storms blow over larger areas of open water on their way north. And that gives them a chance to pick up more heat and moisture from the sea that they carry into the Arctic， causing stronger heat waves.
Alexeev presented his results in December at the Fall Meeting of the American Geophysical Union in San Francisco.
Another study by Kent Moore， an atmospheric physicist at the University of Toronto， came out around the same time as the meeting and also linked the heat waves to storms passing over more and more open water. That research is in the journal Scientific Reports.
Alexeev says the situation could be an example of what scientists call a positive feedback： warming causes the loss of sea ice， which promotes more warming and even more ice loss. In other words， it＇s a snowball effect—or in this case， an anti-snowball effect.
Thanks for the minute for Scientific American — 60-Second Science Science. I＇m Julia Rosen.
這里是科學(xué)美國(guó)人——60秒科學(xué)。我是朱莉婭·羅森。
有一分鐘時(shí)間嗎？
去年圣誕節(jié)，圣誕老人一定是穿著T恤和短褲往雪橇上裝禮物。北極點(diǎn)的溫度攀升至冰點(diǎn)，而正常溫度應(yīng)該是零下二十華氏度。
這是席卷北極的最新一股熱浪，而最近幾個(gè)冬季北極一直飽受熱浪的困擾。氣候變化導(dǎo)致該地區(qū)持續(xù)變暖。同時(shí)也導(dǎo)致了一些極端事件的增加，科學(xué)家認(rèn)為這些事件與北大西洋風(fēng)暴氣旋有關(guān)。
“這些風(fēng)實(shí)際上攜帶著很多熱量和水分。”
弗拉基米爾·阿列謝夫是阿拉斯加大學(xué)費(fèi)爾班克斯分校的氣候?qū)W家。
“大氣把所有額外的水分和熱量帶到北極中心，這導(dǎo)致空氣變得更溫暖濕潤(rùn)。”
然后使地面升溫。
阿列謝夫表示，這些風(fēng)暴使熱量向北移動(dòng)，降低冬季海冰的增長(zhǎng)速度，繼而導(dǎo)致海冰在冬季結(jié)束時(shí)的厚度減少約15厘米。變薄的海冰可能很難熬過夏天。
阿列謝夫說，雖然近幾十年來這些風(fēng)暴帶來的影響日益增加，風(fēng)暴本身并沒有頻繁發(fā)生。
“一條重要的信息是，這些風(fēng)暴的頻率沒有發(fā)生改變。變化的是這些地區(qū)開放水域的面積。”
隨著大西洋溫度升高，斯堪的納維亞和西伯利亞周圍的冬季海冰面積也在縮小。所以現(xiàn)在，風(fēng)暴在向北移動(dòng)的過程中，并不是越過被冰雪覆蓋的海洋，而是經(jīng)過大面積的開放水域。這使風(fēng)暴有機(jī)會(huì)從海洋獲得更多的熱量和水分，然后將這些熱量和水分帶到北極，引發(fā)更強(qiáng)的熱浪。
阿列謝夫在12月于舊金山舉行的美國(guó)地球物理學(xué)聯(lián)合會(huì)秋季會(huì)議上公布了他的研究結(jié)果。
肯特·莫爾是多倫多大學(xué)的大氣物理學(xué)家，他也在會(huì)議同一時(shí)間公布了他的一項(xiàng)研究成果，而這項(xiàng)研究同樣認(rèn)為，熱浪的產(chǎn)生是因?yàn)轱L(fēng)暴經(jīng)過的開放水域越來越多。該研究結(jié)果發(fā)表在《科學(xué)報(bào)告》期刊上。
阿列謝夫說，這種情況可能成為科學(xué)家稱之為“正反饋”的例證：升溫導(dǎo)致海冰減少，海水減少又促進(jìn)氣候變暖和更多的海冰損失。換句話說，這相當(dāng)于滾雪球效應(yīng)，其實(shí)在這種情況下應(yīng)該是反滾雪球效應(yīng)。
謝謝大家收聽科學(xué)美國(guó)人——60秒科學(xué)。我是朱莉婭·羅森。
重點(diǎn)講解：
1. creep up （比率或數(shù)值）逐漸增長(zhǎng)；
例句：The inflation rate has been creeping up to 9.5 per cent.
通貨膨脹率已攀升至9.5%。
2. result in 導(dǎo)致；引起；造成；
例句：Acting before thinking always results in failure.
做事不先考慮總會(huì)導(dǎo)致失敗。
3. come out 出版，發(fā)行；
例句：He has written two articles for the journal， one to be published in this issue， the other to come out in the next.
他為這家雜志寫了兩篇稿子，一篇即將在本期發(fā)表，另一篇將在下期刊載。
4. in other words 換言之；換句話說；也就是說；
例句：In other words， this kind of question is often a lead-in to a suggestion or invitation.
換言之，這種問題通常是建議或邀請(qǐng)的開場(chǎng)白。