2004年的賣座電影《明天過後》,描繪出美國紐約市因全球暖化而遭受颶風、海嘯及水患的侵襲,然這樣戲劇化的電影場景將可能真實上演。美國太空總署暨哥倫比亞大學的研究人員,在本週舉行的一場學術會議中,展示了2050年紐約市周邊海平面上升的情形,然而其結果就如同電影情境所展現的一般。
自2004年就在紐約市環保部工作的科學家羅森維格(Cynthia Rosenzweig)和高妮茲(Vivien Gornitz)表示,海平面上升結合3級颶風所引起的風暴潮,將使紐約市大部分地區在2050年沉入海底,造成大眾運輸系統全數停擺。科學家已能利用電腦模擬未來氣候型態和水位上升情景,近來電腦系統更模擬另一幅具體藍圖,描繪紐約市在2050年的情況。
紐約市有超過800萬人口,加上位於颶風區內,也曾受颶風席捲,因此,每年颶風季節(6月1日到11月30日)都倍受關注。
20世紀期間,海平面大約每年上升1.7到1.8公厘,然而,但在過去10年,數字已經暴增到每年上升3公厘。 2001年,跨政府氣候變化專業小組所提出的報告估計,到2100年以前,全球每年上升溫度會從攝氏1.4度增加到5.8度,暖化會帶動海平面上升速度從每年9公分增加到88公分。
高妮茲表示,倘若海平面上升到這種高度,紐約市許多低漥地區和大眾運輸系統就更容易因暴風雨而慘遭淹沒,颶風所引起的風暴潮也可能造成更高的風險。
風暴潮是颶風所造成海面上升的現象,依照辛普森颶風等級可分為五級,五級颶風是最高等級、具有最強的破壞性。到2050年,海平面只需上升1.5呎,再配合一個最嚴重路徑的三級颶風,就可以在紐約市許多地區造成嚴重水災。
根據1995年「颶風對紐約大眾運輸影響研究報告」,行經最嚴重路徑的三級颶風足以在甘迺迪機場、林肯隧道、砲台公園、La Giadia機場各形成25呎、21呎、24呎和16呎風暴潮,這還沒加上潮汐和風浪所增加的效應。
The 2004 movie The Day After Tomorrow painted an apocalyptic vision of a New York City battered by hurricanes, tidal waves and floods induced by global warming. A new study being presented at a science meeting this week provides a detailed picture of sea level rise around New York by the 2050s and paints a scenario similar to that dramatized by the big budget blockbuster.
Rising sea levels combined with the storm surge of a category three hurricane would leave much of a 2050s New York underwater and the city's entire metropolitan transportation system shut down, say scientists Cynthia Rosenzweig and Vivien Gornitz.They have been working with New York City's Department of Environmental Protection since 2004, using computer models to simulate future climates and sea level rise. Recently, computer modeling studies have provided a more detailed picture of sea level rise around New York by the 2050s.
Inhabited by more than eight million people, New York City has long been an area of concern during hurricane season, which usually runs from June 1 to November 30. It has been hit before.
During most of the 20th century, sea levels around the world have been rising by 1.7 to 1.8 millimeters (0.07 inches) per year. That figure has increased to nearly 3 mm (0.12 in) per year within the last decade. The 2001 report of the Intergovernmental Panel on Climate Change found that a global warming of 1.4 to 5.8 degrees Celsius (2.5 to 10.4 Fahrenheit) could lead to a sea level rise of 0.09 to 0.88 meters (four inches to 2.9 feet) by 2100.
"With sea level at these higher levels, flooding by major storms would inundate many low-lying neighborhoods and shut down the entire metropolitan transportation system with much greater frequency," said Gornitz. As sea levels rise, so does the risk of a hurricane storm surge in New York City, Gornitz said.
Storm surge is an above normal rise in sea level accompanying a hurricane. Hurricanes are categorized on the Saffir-Simpson scale, from one to five, with five being the strongest and most destructive. Adding as little as 1.5 feet of sea level rise by the 2050s to the surge for a category three hurricane on a worst-case track would cause extensive flooding in many parts of the city, said Gornitz.
According to the 1995 Metro New York Hurricane Transportation Study, a category three hurricane on a worst-case track could create a surge of up to 25 feet at JFK Airport, 21 feet at the Lincoln Tunnel entrance, 24 feet at the Battery, and 16 feet at La Guardia Airport. These figures do not include the effects of tides or the additional heights of waves on top of the surge.