2010/12/20 12:52洪美惠
摘譯自2010年12月13日ENS美國，加州，巴沙迪那市報導；張桂芳編譯；蔡麗伶審校
根據首度針對全球各大湖泊進行全面性水溫調查結果顯示，過去25年來氣候變遷的現象導致各大湖泊水溫呈現持續上升趨勢。
美 國國家航空暨太空總署巴沙迪那噴氣推進實驗室(NASA Jet Propulsion Laboratory in Pasadena)研究人員菲利普施耐德（Philipp Schneider）和西蒙胡克（Simon Hook）利用於1985-2009年間拍攝的衛星數據來測量全球167大湖泊的湖面溫度進而發現此現象。
數據顯示位於北半球的中高緯度地區暖幅較南半球的低緯度地區大。
歐洲北部為暖幅最大和不斷穩定升溫的地區，而位於歐洲東南部的黑海、裡海和哈薩克斯坦暖化的趨勢則較不明顯。另外，偏東半球的西伯利亞、蒙古北部和中國暖化趨勢也有增加的跡象。
就北美地區而言，美國西南部暖化趨勢比五大湖區（the Great Lakes region）略高。其中北美最大高山湖泊太浩湖（Lake Tahoe），位於加利福尼亞州與內華達州邊界，就是這項全球湖泊研究結果最好的例證。
五大湖區和北歐水溫暖化的速度甚至比其周邊空氣升溫的速度更快。
熱帶和南半球的中緯度地區暖化的情況則不那麽明顯。
施耐德指出，微幅的水溫變化很可能導致藻類大量繁殖，進而產生毒素對湖泊中魚類不利，或造成非本地物種的引入，改變了湖泊原有的自然生態系。
自1985年以來，透過夜間熱紅外圖像攝取技術，截取了各地167個大型內陸湖泊7至9月和1至3月的湖面溫度。
季節性天候因素如湖面被冰雪或常態性雲層覆蓋，而導致資料搜集困難所形成的結果為挑選這些月份的主因。
研究人員發現，每10年平均增溫率為華氏0.81度。其中部分湖泊每10年的增溫更高達華氏1.8度。
施奈德和胡克當初從全球湖泊和濕地資料庫中按面積大小篩選出研究的標地 -原則上至少為193平方英里或更大- 或具有其他獨特的科學研究價值特性。
此外，爲了避免地表溫度影響測量結果，選定的湖泊必須有相當程度的湖面面積是遠離岸邊的。因此衛星所採集數據的地方通常為距離各岸邊最遠的地點。
施奈德和胡克表示，研究結果與預期中全球暖化連帶產生的變化不謀而合。Earth's Largest Lakes Are Heating UpPASADENA, California, December 13, 2010 (ENS)
Earth's largest lakes have been warming during the past 25 years in response to climate change, according to the first comprehensive global survey of temperature trends in major lakes.
Researchers Philipp Schneider and Simon Hook of the NASA Jet Propulsion Laboratory in Pasadena, made the discovery using satellite data from 1985-2009 to measure the surface temperatures of 167 large lakes worldwide.
The data show far greater warming in the mid- and high latitudes of the Northern Hemisphere than in low latitudes and the southern hemisphere.
The largest and most consistent area of warming was northern Europe. The warming trend was slightly weaker in southeastern Europe, around the Black and Caspian seas and Kazakhstan. The warming trends increased slightly farther east in Siberia, Mongolia and northern China.
In North America, trends were slightly higher in the southwest United States than in the Great Lakes region. The largest alpine lake in North America, Lake Tahoe, on the California-Nevada border, was one of the primary validation sites for the global lake study.
In the Great Lakes and northern Europe, the bodies of water were found to be warming even more quickly than surrounding air temperature.
Warming was weaker in the tropics and in the mid-latitudes of the Southern Hemisphere.
Small changes in water temperature can result in algal blooms that can make a lake toxic to fish or result in the introduction of non-native species that change the lake's natural ecosystem, Schneider explained.
Beginning in 1985, surface temperatures were extracted from nighttime thermal infrared imagery of 167 large inland water bodies for the months July through September and January through March.
These months were chosen because of the difficulty in collecting data in seasons when lakes are ice-covered or often hidden by clouds.
The researchers found an average warming rate of 0.81 degrees Fahrenheit per decade, with some lakes warming as much as 1.8 degrees Fahrenheit per decade.
Schneider and Hook selected the study lakes from a global database of lakes and wetlands based on size - typically at least 193 square miles or larger - or other unique characteristics of scientific merit.
The selected lakes also had to have large surface areas located away from shorelines, so land influences did not interfere with the measurements. Satellite data were collected from the point farthest from any shoreline.
Schneider and Hook said that their results were consistent with the expected changes associated with global warming.
全文及圖片詳見：ENS報導
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