夏威夷山火造成了極具毀滅性的破壞,這似乎是由強風、低濕度和干燥的植被等眾多危險因素共同導致的。
專家也表示,氣候變化增加了更多像毛伊島大火這類極端天氣事件發生的可能性——這場災難造成至少6人死亡,并摧毀了一個歷史旅游小鎮。
不列顛哥倫比亞大學(University of British Columbia)林業學院的博士后研究員凱爾茜?科佩斯-格比茨(Kelsey Copes-Gerbitz)說:“氣候變化導致了我們現在看到的各種難以預測或始料不及的因素,它們共同引發了這類極端火災天氣。這些……毀滅性的山火災難揭示了無處能幸免于氣候變化的影響。”
因何而起?
據氣象學家稱,氣壓的巨大差異導致了特別強勁的信風,助長了這場破壞性大火的蔓延。
信風是夏威夷的典型氣候特征。當空氣從夏威夷以北的高壓帶(即北太平洋高壓)移動到赤道的低氣壓帶到達該州的南部時,就會出現這種自然現象。
不過,美國國家氣象局(National Weather Service)火奴魯魯辦公室的氣象學家讓坎·基諾(Genki Kino)表示,本周從夏威夷群島經過的颶風多拉(Hurricane Dora)使得低壓系統增強,加大了氣壓差,從而產生了“特別強勁的信風”。
強風加上低濕度和大量易燃的干燥植被會增加發生火災的危險,即使在像毛伊島這樣的熱帶島嶼也是如此。
俄勒岡州立大學(Oregon State University)俄勒岡氣候變化研究所(Oregon Climate Change Research Institute)所長埃里卡·弗萊什曼(Erica Fleishman)說:“如果所有這些情況同時出現,那往往就是國家氣象局通常所說的‘紅色警報情況’。”
氣候變化發揮著怎樣的影響
弗萊什曼表示:“全球許多地區的植被都變得更加干燥,很大程度上是因為氣候變化導致氣溫升高。即使降水量不變,如果溫度上升,東西也會干得更快。”
夏威夷大學(University of Hawaii)火災科學家克萊·特勞爾尼希特(Clay Trauernicht)說,雨季可以促進幾內亞草(在毛伊島部分地區發現的一種外來入侵物種)等植物快速生長,使它們能夠每天長6英寸(15厘米),最高可長到10英尺(3米)。這些植物干枯后,就會成為容易引發野火的易燃物。
特勞爾尼希特表示:“這些草地會迅速積累燃料。由于天氣更加炎熱和干燥,加上降雨量變化無常,這只會加劇問題。”
氣候變化不僅會造成氣溫升高,從而增加火災風險,還會使得發生強颶風的可能性增大。這些風暴進而又會引發更嚴重的風災事件(如導致毛伊島大火的風災事件)。
除此之外,氣候變化還加劇了其他一些威脅。
弗萊什曼說:“在全球范圍內,颶風的強度正呈現上升趨勢,部分原因是變暖的空氣容納了更多的水分。此外,由于全球海平面正在上升,當颶風登陸時,風暴潮往往會導致更嚴重的洪水。”
專家們表示,雖然不能說氣候變化直接導致了單個事件的發生,但極端天氣對社會帶來的影響是不可否認的。
不列顛哥倫比亞大學的科佩斯-格比茨說:“我們以往確實沒有應對過這類由氣候變化引起的災難。正是這些來自多方面且相互影響的挑戰真正導致了災難。”(財富中文網)
譯者:中慧言-劉嘉歡
夏威夷山火造成了極具毀滅性的破壞,這似乎是由強風、低濕度和干燥的植被等眾多危險因素共同導致的。
專家也表示,氣候變化增加了更多像毛伊島大火這類極端天氣事件發生的可能性——這場災難造成至少6人死亡,并摧毀了一個歷史旅游小鎮。
不列顛哥倫比亞大學(University of British Columbia)林業學院的博士后研究員凱爾茜?科佩斯-格比茨(Kelsey Copes-Gerbitz)說:“氣候變化導致了我們現在看到的各種難以預測或始料不及的因素,它們共同引發了這類極端火災天氣。這些……毀滅性的山火災難揭示了無處能幸免于氣候變化的影響。”
因何而起?
據氣象學家稱,氣壓的巨大差異導致了特別強勁的信風,助長了這場破壞性大火的蔓延。
信風是夏威夷的典型氣候特征。當空氣從夏威夷以北的高壓帶(即北太平洋高壓)移動到赤道的低氣壓帶到達該州的南部時,就會出現這種自然現象。
不過,美國國家氣象局(National Weather Service)火奴魯魯辦公室的氣象學家讓坎·基諾(Genki Kino)表示,本周從夏威夷群島經過的颶風多拉(Hurricane Dora)使得低壓系統增強,加大了氣壓差,從而產生了“特別強勁的信風”。
強風加上低濕度和大量易燃的干燥植被會增加發生火災的危險,即使在像毛伊島這樣的熱帶島嶼也是如此。
俄勒岡州立大學(Oregon State University)俄勒岡氣候變化研究所(Oregon Climate Change Research Institute)所長埃里卡·弗萊什曼(Erica Fleishman)說:“如果所有這些情況同時出現,那往往就是國家氣象局通常所說的‘紅色警報情況’。”
氣候變化發揮著怎樣的影響
弗萊什曼表示:“全球許多地區的植被都變得更加干燥,很大程度上是因為氣候變化導致氣溫升高。即使降水量不變,如果溫度上升,東西也會干得更快。”
夏威夷大學(University of Hawaii)火災科學家克萊·特勞爾尼希特(Clay Trauernicht)說,雨季可以促進幾內亞草(在毛伊島部分地區發現的一種外來入侵物種)等植物快速生長,使它們能夠每天長6英寸(15厘米),最高可長到10英尺(3米)。這些植物干枯后,就會成為容易引發野火的易燃物。
特勞爾尼希特表示:“這些草地會迅速積累燃料。由于天氣更加炎熱和干燥,加上降雨量變化無常,這只會加劇問題。”
氣候變化不僅會造成氣溫升高,從而增加火災風險,還會使得發生強颶風的可能性增大。這些風暴進而又會引發更嚴重的風災事件(如導致毛伊島大火的風災事件)。
除此之外,氣候變化還加劇了其他一些威脅。
弗萊什曼說:“在全球范圍內,颶風的強度正呈現上升趨勢,部分原因是變暖的空氣容納了更多的水分。此外,由于全球海平面正在上升,當颶風登陸時,風暴潮往往會導致更嚴重的洪水。”
專家們表示,雖然不能說氣候變化直接導致了單個事件的發生,但極端天氣對社會帶來的影響是不可否認的。
不列顛哥倫比亞大學的科佩斯-格比茨說:“我們以往確實沒有應對過這類由氣候變化引起的災難。正是這些來自多方面且相互影響的挑戰真正導致了災難。”(財富中文網)
譯者:中慧言-劉嘉歡
A dangerous mix of conditions appear to have combined to make the wildfires blazing a path of destruction in Hawaii particularly damaging, including high winds, low humidity and dry vegetation.
Experts also say climate change is increasing the likelihood of more extreme weather events like what’s playing out on the island of Maui, where at least six people have been killed and a historic tourist town was devastated.
“It’s leading to these unpredictable or unforeseen combinations that we’re seeing right now and that are fueling this extreme fire weather,” said Kelsey Copes-Gerbitz, a postdoctoral researcher at the University of British Columbia’s faculty of forestry. “What these … catastrophic wildfire disasters are revealing is that nowhere is immune to the issue.”
WHAT’S FUELING THEM?
Major differences in air pressure drove unusually strong trade winds that fanned the destructive flames, according to meteorologists.
Trade winds are a normal feature of Hawaii’s climate. They’re caused when air moves from the high-pressure system pressure north of Hawaii — known as the North Pacific High — to the area of low pressure at the equator, to the south of the state.
But Hurricane Dora, which passed south of the islands this week, is exacerbating the low-pressure system and increasing the difference in air pressure to create “unusually strong trade winds,” said Genki Kino, a meteorologist with the National Weather Service office in Honolulu.
Strong winds, combined with low humidity and an abundance of dry vegetation that burns easily, can increase the danger, even on a tropical island like Maui.
“If you have all of those conditions at the same time, it’s often what the National Weather Service calls ‘red flag conditions,’” said Erica Fleishman, director of the Oregon Climate Change Research Institute at Oregon State University.
HOW CLIMATE CHANGE PLAYS A ROLE
“Climate change in many parts of the world is increasing vegetation dryness, in large part because temperatures are hotter,” Fleishman said. “Even if you have the same amount of precipitation, if you have higher temperatures, things dry out faster.”
Clay Trauernicht, a fire scientist at the University of Hawaii, said the wet season can spur plants like Guinea grass, a nonnative, invasive species found across parts of Maui, to grow as quickly as 6 inches (15 centimeters) a day and reach up to 10 feet (3 meters) tall. When it dries out, it creates a tinderbox that’s ripe for wildfire.
“These grasslands accumulate fuels very rapidly,” Trauernicht said. “In hotter conditions and drier conditions, with variable rainfall, it’s only going to exacerbate the problem.”
Climate change not only increases the fire risk by driving up temperatures, but also makes stronger hurricanes more likely. In turn, those storms could fuel stronger wind events like the one behind the Maui fires.
That’s on top of other threats made worse by climate changes.
“There’s an increasing trend in the intensity of hurricanes worldwide, in part because warm air holds more water,” Fleishman said. “In addition to that, sea levels are rising worldwide, so you tend to get more severe flooding from the storm surge when a hurricane makes landfall.”
While climate change can’t be said to directly cause singular events, experts say, the impact extreme weather is having on communities is undeniable.
“These kinds of climate change-related disasters are really beyond the scope of things that we’re used to dealing with,” UBC’s Copes-Gerbitz said. “It’s these kind of multiple, interactive challenges that really lead to a disaster.”