全球棲地溫暖化 | 環境資訊中心

全球棲地溫暖化

2000年09月11日
ENS報導;許嘉玲 翻譯 ;鄭伊娟 審校

想像一下: 北極出現了落葉森林根據世界自然基金會的一份報告指出,地球溫暖化的結果將在未來一百年內改變全球近三分之一的棲地。

世界保育基金會氣候變化運動的發言人,卡拉瑞那迪表示,[全球溫暖化和陸地生態多樣性的驟減]是第一份試著用總量來表示全球溫暖化對全球陸域物種消失的影響的報告。

圖表北極熊是受全球溫暖化影響最多的物種之一。研究報告指出北極熊個體體型的縮小。

早期溫室效應對全球生態系的影響的研究,都努力建立溫室效應對生態系中能源和物質循環的影響的對應關係上,而忽略了對組成生態系的物種的影響。

研究報告發現問題在於許多動植物將無法適應棲地的改變。

多倫多大學森林系教授,也是這份報告的共同發表者,傑麥肯表示,全球溫暖化的加速,使得動植物找尋合適的棲地的壓力也急遽增加。

根據報告指出,這次全球溫暖化的速度預計將比一萬三千多年前的最後一次冰河時期的地球氣候溫暖化速度還快。

科學家相信,氣候的改變是導致類似saber-toothed tiger和woolly mammoth等物種消失的原因。

清靜的空氣-涼爽的星球(Clean Air-Cool Planet)的執行長,同時也是這份報告的共同發表人,亞當馬克漢表示,這次物種的移動速度必須比上次的冰河時期還要快十倍。

報告預測,北半球,加拿大,蘇俄,斯堪地半島等地區的改變將會最大,將近百分之七十的棲地會消失。

根據報告表示,美國只有少數地區得以倖免。緬因州, 新罕布夏,奧瑞岡州,科羅拉多州,懷俄明州,愛達荷州,猶他州,亞利桑那州,堪薩斯州,奧克拉荷馬州,和德州等十一州三分之一的棲地將會改變。

馬克漢表示,楓樹(sugar maple),一種東北溫帶硬木森林的代表物種很有可能會完全從新英格蘭消失,成為加拿大森林的物種。

稍早的研究發現,許多物種早已到全球溫暖化的影響。作者表示,在鳥類方面,例如蘇格蘭的great tit(一種山雀)和亞利桑那的墨西哥橿鳥(Mexican jay,一種鴉科的鳥)都已較早育雛;蝴蝶也搬移了他們的棲地,分布到北歐各地;北極圈的哺乳類,例如北極熊,海象 和北美馴鹿也開始受到海冰減少以及寒原棲地溫暖化的影響。

作者表示,全球溫暖化預言的未來都是根據國際氣候變化小組尚未完成的研究報告所描繪。這個由兩百多個科學家所組成專家小組從1990年初就開始研究氣候的變化。根據IPCC的保守估計,下一世紀,大氣中的二氧化碳總量將會是工業革命前的兩倍。更有甚者,部分科學家預計在西元2100年時,大氣中的二氧化碳總量將會增加三倍。

有些物種能以快速遷移的方式因應急速溫暖,本報告也將人類對上述物種存活的影響納入考量。

馬克漢解釋說,今日的環境讓物種比以往更難遷徙。稀有的,被孤立(可否改為隔離)的或是移動緩慢的物種將無法打敗適應和移動快的雜草和蟲子。

馬克漢說,我們能幫這些野生物適應氣候變遷的方法也只有停止破壞他們的棲地了。我們保留了越多的棲地,生物就會有越大的復原力來適應環境的變遷。相反的,環境越被破壞,生物就越脆弱。

World's habitat feeling the heat of climate change

Imagine a deciduous forest in the Arctic. 

Global warming could dramatically alter a third of the world's natural habitat over the next 100 years, according to a study released Wednesday by the World Wide Fund for Nature. 

"Global Warming and Terrestrial Biodiversity Decline" is the first attempt to quantify the possible loss of land-based species on a global scale as a result of global warming, said Kara Rinaldi of the World Wide Fund's climate change campaign. 

Polar bears are among the most affected by global warming. Studies show diminished body size in many bears.

Previous efforts to model the potential effects of greenhouse warming on global ecosystems focused on flows of energy and matter through ecosystems rather than on species that make up ecosystems. 

The problem, the report finds, is that many plant and animal species will not be able to keep up with the modification of their habitat. 

"As global warming accelerates, plants and animals will come under increasing pressure to migrate to find suitable habitat," said Jay Malcom, a forestry professor at the University of Toronto and a co-author of the report. 

According to the report, the rate of warming is expected to be much faster than the rate of warming that occurred during the most recent ice age 13,000 years ago. 

Scientists believe that climate change led to the extinction of such species as the saber-toothed tiger and the woolly mammoth. 

"Species will have to move 10 times faster than last time," said Adam Markham, executive director of Clean Air-Cool Planet and a co-author of the report. 
In the northern latitudes of Canada, Russia and Scandinavia, where warming is predicted to be most rapid, up to 70 percent of habitat could be lost, the report notes.

In the United States, few regions will be spared, according to the report. More than a third of existing habitats in 11 states - Maine, New Hampshire, Oregon, Colorado, Wyoming, Idaho, Utah, Arizona, Kansas, Oklahoma and Texas - could be changed from what they are today.

"It is likely that sugar maples - a cold-weather species that is characteristic of the Northeast's hardwood forests - will be pushed completely out of New England to Canada," Markham said. 

Previous studies found that many species are already affected by global warming. Birds such as the great tit in Scotland and the Mexican jay in Arizona are breeding earlier in the year, the authors note. Butterflies are shifting their ranges to the north throughout Europe, and mammals in many parts of the Arctic, including polar bears, walrus and caribou, are beginning to suffer from the impact of reduced sea ice and warming tundra habitat. 

Projections of global warming were based on middle-of-the road estimates by the International Panel on Climate Change, a panel of more than 2,000 scientists who have examined climate change since the early 1990s, the authors note. According to moderate IPCC predictions, the amount of carbon dioxide in the atmosphere will double from pre-industrial levels over the next century. Nevertheless, some scientists suggest a three-fold increase in concentrations by 2100. 

The report factors the effect of human influence on the survival of those species able to migrate fast enough to keep pace with rapid warming. 

Conditions today make it harder for species to move than ever before, Markham explained. Rare, isolated or slow-moving species could lose out to weeds and pests that can move or adapt quickly. 

"The best thing we can do to help wildlife adapt to climate change is to stop destroying their habitat," Markham said. "The more habitat we leave, the more resilient wildlife will be to climate change. The more we mess it up, the more vulnerable wildlife will be."