全球變暖導致更多颶風?

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  • #3444
    馬丁
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      Just published research suggests that numbers of Atlantic hurricanes are rising, and part of this rise is due to global warming. Been plenty of arguments re warming and hurricanes (major tropical cyclones; known as typhoons here in Hong Kong and other parts of Pacific/S China Sea). But, has always seemed likely: hurricanes form over warm seas, so as seas warm, can expect more – and more intense – tropical cyclones.

      Yes, also seen Johnny Chan, HK researcher, who has found that over the Pacific, it's important ot also consider winds/air currents that can destroy these storms before they form: and these too may increase with warming, cancelling out effect of warming seas. (Plus, tropical Pacific warmer than Atlantic; temps generally well above those needed to form trop cyclones, while Atlantic more typically around the threshold level, so warming there can have more of an effect. [this guff partly from answer I asked Prof Chan at a global warming workshop, plus from his talk]) But interesting, too, to see that S America (east coast) lately had it's first tropical storm.

      And, just a few weeks ago, Arabian Peninsula hit by strongest cyclone since record keeping began there in 1945. For the latter: http://www.sciencedaily.com/releases/2007/06/070613070547.htm Also, even been computer models suggesting hurricane force storms just might impact the Mediterranean should warming continue. Back to the hurricane research; info on Scientific American site includes:

      引用:
      Using records dating back to 1855, hurricane researchers say they have uncovered an ongoing rise in the number of Atlantic hurricanes that tracks the increase in sea surface temperature related to climate change. Critics of such a link argue that this trend is merely because of better observations since the dawn of the satellite era in the 1970s. But the authors of the new study say the conclusion is hard to dodge.

      "Even if we take the extreme of these error estimates, we are left with a significant trend since 1890 and a significant trend in major hurricanes starting anytime before 1920," say atmospheric scientists Greg Holland of the National Center for Atmospheric Research in Boulder, Colo., and Peter Webster of the Georgia Institute of Technology in Atlanta. … The experts agree that natural variability is largely to blame for the relative intensity of various hurricanes, but Holland and Webster note that the locations of such storms have changed. "As more storms form near the equator, they are experiencing much better conditions for intensification and they are experiencing these conditions for a much longer period," the pair note. And that means more numerous and stronger hurricanes in the foreseeable future, whether the forecast is from a computer model or a meteorologist's instincts.

      Stronger Link Found between Hurricanes and Global Warming A century's worth of records suggests that hurricanes are on the rise and a warming Atlantic is to blame

      #4497
      馬丁
      參加者

        克里斯·穆尼 (Chris Mooney) 寫了一篇好文章,他寫了一本關於颶風/熱帶氣旋強度與全球暖化之間明顯聯繫的書。使用目前的颶風迪恩作為起點,包括:

        引用:
        迪恩現已躋身大西洋十大最強颶風之列。如果您查看該列表,您會發現過去十年中最強的六位(威爾瑪、麗塔、卡特里娜、米奇、迪恩和伊凡)都曾出現過。這不是一種容易被忽略的統計數據。根據這些數據,我們在大西洋盆地遇到的超強風暴比以往任何時候都多。

        可以肯定的是,這裡有一個反駁:以前時代的颶風強度數據並不像今天那麼好,當時我們的測量設備比以往任何時候都更好。過去很可能存在更強的風暴,但我們根本無法偵測到它們的真正強度。

        這是一個嚴重的反對意見,儘管很難確切知道有多嚴重。儘管如此,事實仍然是,如果你看一下官方記錄,迪恩現在正處於令人震驚的颶風十年。這是非常有啟發性的,即使不是明確的。這個驚人的十年的部分原因是颶風多發地區的海洋溫度異常溫暖。許多科學家質疑是否可以在不將全球暖化作為至少部分原因的情況下解釋這些溫暖異常。

        根據我正在進行的「風暴專家」對巨型颶風的統計,迪恩是今年全球觀測到的第 10 個 4 或 5 級熱帶氣旋。 [穆尼列出風暴]

        根據我自己的統計,2006 年發生了19 次強烈風暴,2005 年發生了22 次,2004 年發生了23 次。颶風專家傑夫·馬斯特斯(Jeff Masters) 表示,長期平均值為17 次,在這種情況下,所有這些年都會高於該值,我們可能會確實在關註一個趨勢。

        颶風迪恩:有史以來測量到的 10 個最強烈的大西洋颶風之一

        #4498
        馬丁
        參加者

          I’ve seen that numbers of west Pacific typhoons may decrease with global warming – as wind shear increases, so it’s harder for them to form. Now, first news I’ve noticed that maybe this will be true for Atlantic – albeit contentious. Must still wonder if warmer seas will lead to more strong storms (ie, powerful trop cyclones) – ie once they start forming, tend to become powerful, maybe fast.

          引用:
          Global warming could reduce how many hurricanes hit the United States, according to a new federal study that clashes with other research. The new study is the latest in a contentious scientific debate over how man-made global warming may affect the intensity and number of hurricanes. In it, researchers link warming waters, especially in the Indian and Pacific oceans, to increased vertical wind shear in the Atlantic Ocean near the United States. Wind shear — a change in wind speed or direction — makes it hard for hurricanes to form, strengthen and stay alive. So that means "global warming may decrease the likelihood of hurricanes making landfall in the United States," according to researchers at the National Oceanic and Atmospheric Administration’s Miami Lab and the University of Miami. … Critics say Wang’s study is based on poor data that was rejected by scientists on the Nobel Prize-winning Intergovernmental Panel on Climate Change. They said that at times only one in 10 North Atlantic hurricanes hit the U.S. coast and the data reflect only a small percentage of storms around the globe.

          Study: Warming May Cut US Hurricane Hits

          #4543

          來自英國廣播公司新聞:

          引用:

          The strongest tropical storms are becoming even stronger as the world’s oceans warm, scientists have confirmed.

          Analysis of satellite data shows that in the last 25 years, strong cyclones, hurricanes and typhoons have become more frequent in most of the tropics.

          Writing in the journal Nature, they say the number of weaker storms has not noticeably altered.

          James Elsner from Florida State University in Tallahassee, US and colleagues believed the link might become clearer if they analysed data according to the strength of storms.

          "We’re seeing a signal, and it’s telling us that the strongest effect (of rising ocean temperatures) is on the strongest storms," he told BBC News.

          "At average or median wind speeds, about 40m/s, we don’t see a trend; but when we get up to 50 or 60m/s we do see a trend."

          The increase in strong storms shows up most markedly in the North Atlantic and Indian oceans, and is absent in the South Pacific.

          "We’re looking at different ocean basins, and some are already pretty warm," said Professor Elsner.

          "So there, an increase in temperature isn’t going to produce as strong an increase as in basins where the the temperatures are only marginally supportive of cyclones."

          Warming Boosts Strongest Storms

          #4682

          From Christian Science Monitor:

          引用:
          The number of hurricanes, typhoons, and tropical storms globally is likely to either fall or remain flat over the course of the 21st century. But an increasing proportion of the storms are likely to hit the highest levels of intensity because of the projected effects of global warming, an international team of scientists concludes.

          Skip to next paragraph

          However, it's unclear whether past trends in the number and intensity of storms – which some research suggested may be due to global warming – fall outside the range of natural variation. This is particularly true of the Atlantic basin, the team writes.

          Number of storms may drop, but more could be intense, study says

          #4685
          引用:
          Global warming is raising the danger from typhoons, Taiwan experts warned Monday, saying the island may be hit in a year or two by a powerful storm like the one which killed more than 700 last August.

          Typhoon Morakot dumped a record 3,000 millimetres (120 inches) of rainfall and caused massive mudslides in the south of the island, and the government should be prepared for similar disasters in the future, they said.

          "A typhoon as powerful as Morakot is very likely to strike Taiwan in a year or two," said Wang Chung-ho, a research fellow at the Institute of the Earth Sciences at Taiwan's top academic body Academia Sinica.

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