全球暖化效應 美水患危機升高 | 環境資訊中心

全球暖化效應 美水患危機升高

2008年07月09日
摘譯自2008年7月2日 ENS 美國,華盛頓報導;楊佳珊、禾引編譯;蔡麗伶審校

位於愛荷華州的伯靈頓,在2008年6月被洪水侵襲的情況。圖片來源:Iowa DOT多位專家於7月1日提出警告,氣候變遷將增加暴風雨發生的次數,且劇烈程度則如美國中西部遭受暴風雨引起的嚴重水災。然而,由於目前政府關於洪水預測及居家保險計畫,都未考量到氣候變遷的問題,也因此讓中西部居民面臨洪水威脅時,充滿了不確定性。

美國野生動物基金會(National Wildlife Federation)氣候科學家史都(Amanda Staudt)表示,「儘管不能將單一氣候事變歸因於全球暖化,但必須要了解,暖化的氣候一直以來確實醞釀出,助長各種氣候事變發生的環境。」

史都也提到,自1960年代末以來,中西部地區豪雨的次數躍增了20%,而過去大約每20年發生一次的強烈暴風雨,現在可能每5年就會有一次。

「全球暖化衍生的後續問題逐漸浮出,以水患次數更加頻繁嚴重就是其中一例。」史都在電話訪談中表示,「隨著氣候持續暖化,以及空氣濕度日益增加,進而引發愈多劇烈氣候事變將成為一個趨勢。」

根據美國官方表示,美中西部近35年來,已發生2起當代百年出現一次的洪水,而在1993年與最近的2起水患,則是相當於500年出現一次的洪水。

南伊利諾大學地質學暨洪水研究員平特(Nicholas Pinter)表示,「按資料數據與災害程度來看,這些數字並不合理,可見政府對於洪水預測上的缺失。」

美國中西部的水患感脅著人民的生命財產。圖片來源:Iowa DOT「這些事件並非隨機發生,」平特說道,「我們逐漸找出洪水發生的規律性軌跡,且發現遠比預估的還要劇烈頻繁。」

平特說,「由於都是依歷史紀錄、流速及河流海拔高度來做評估,政府機關一直以來都低估了洪水威脅。」

「針對美國陸軍工兵部(U.S Army Corps of Engineers)帶領的機關所用的最新研究,其中假設自然環境從過去至今未曾改變。」

平特向記者表示,「該研究忽略了許多因素,例如:全球暖化所增加的威脅、沒有考慮顯著的土地使用改變、堤防新建工程,及河流改道以減少導航難度等相關因素。」

平特提出解釋說,美國陸軍工程隊確實有將中西部因興建水壩,而讓潛在性洪水降低的利益考慮進去,但也因此又更加低估了洪水威脅。

美國野生動物基金會資深專員康拉德(David Conrad)表示,「用錯誤數據作為全國居家洪水保險計畫的標準,已引發嚴重後果。」

Warming Climate Adds to U.S. Flood Fears
WASHINGTON, DC, July 2, 2008 (ENS)

Climate change will bring an increase in severe storms like the ones responsible for the devastating floods plaguing the U.S. Midwest, experts warned Tuesday. But current government flood forecasts and insurance programs do not consider the effects of global warming, leaving Midwest residents with an incomplete assessment of their flood risks.

"Although no single weather event can be attributed to global warming, it's critical to understand that a warming climate is supplying the very conditions that fuel these kinds of weather events," said Amanda Staudt, a climate scientist with the National Wildlife Federation, NWF.

The frequency of torrential rainstorms in the Midwest has jumped 20 percent since the late 1960s, Staudt said, and large storms that historically would only be seen once every 20 years are projected to happen as often as every five years.

"Global warming is making tragedies like these more frequent and more intense," Staudt told reporters in a telephone briefing. "As climate continues to warm and we have even more moisture in the air, the trend toward increasingly intense weather events will continue."

U.S. officials say the Midwest has seen two 100-year floods in the last 35 years as well as two 500-year floods - one in 1993 and this latest disaster.

Those numbers don't make sense and illustrate the government's flawed flood forecasting, said Nicholas Pinter, a geologist and flood researcher at Southern Illinois University.

"These are not random events," he said. "We are getting a systematic pattern of floods larger and more frequent than estimated by those calculations."

Relying on historical records, flow rates and river elevation, government agencies have consistently underestimated the flooding risks, Pinter said.

The latest study used by agencies, led by the U.S. Army Corps of Engineers, "assumed no natural changes" to the region over time, he said.

It ignored evidence of an increased risk from global warming and failed to consider significant land use changes, new levee construction and modifications to rivers in order to ease navigation, Pinter told reporters.

The Corps' study did include potential flood reduction benefits from dams throughout the Midwest, thereby further underestimating flood risks, Pinter explained.

The faulty estimates, used to set standards for the national flood insurance program, have contributed to the devastation, said David Conrad, a senior resource specialist with the National Wildlife Federation.

全文及圖片詳見:ENS