■專家提議將城市中的柏油路及建築物天台塗成白色，有助紓緩「熱島效應」。 資料圖片【原文】下文摘錄自香港《文匯報》2017年6月5日報道：
科學家早前在《自然氣候變化》（Nature Climate Change）期刊刊出論文，指出飽受「熱島效應」（heat island effect）影響的大都市（megacity），將是氣候變化主要受害者（victim），當中人口最多的一批都市，市內氣溫到本世紀末將上升7℃甚至更高，不但影響市民起居，同時構成龐大經濟損失（economic loss）。
專家建議將道路及建築物天台塗成白色，並栽種更多植物，能有效降低氣溫。
開空調加劇 經濟損失大
開發城市（urbanization）時不免要改造自然環境（natural landscape），例如砍去樹木（vegetation），移除水體，並興建大量柏油路（asphalt pavement）及建築物，它們均會吸收熱能（heat-trapping）。研究發現，若當日氣溫是38℃，建築物的黑色天台日間氣溫可升至88℃。
此外，汽車及冷氣系統均會排出熱氣（waste heat）。因此，大城市氣溫往往較市郊高，這種現象被稱為「熱島效應」。
城市居民需要空調（air-conditioning）保持涼快，這除了加劇「熱島效應」，亦令能源需求（energy consumption）上升。專家指出，氣候暖化會招致經濟損失，以受影響最嚴重的城市為例，累積損失到2100年將佔當地生產總值10.9%。
柏油路改塗白色 可降2℃
城市裡的柏油路普遍是吸熱的黑色，專家提議將它們及建築物天台塗成白色，又或其他有效反射（reflect）熱力的淺色，並增加植樹，有助紓緩「熱島效應」。
以英國倫敦（London）為例，市內氣溫較市郊高約4℃，如果市政府全面採納上述措施，則有助將氣溫降低2℃。就算只改裝（transform）20%道路及建築物，也能降低氣溫0.8℃。長遠來說，措施亦能省下相等於12倍的成本開支。
參與撰寫論文的英國薩塞克斯郡大學（University of Sussex）教授托爾（Richard Tol）稱，各界向來集中在全球層面對抗（tackle）氣候變化，忽略了地區性的變化。專家稱，上述措施對市民生活產生更直接幫助，不過無助阻止全球暖化（global warming），只能減輕影響。
過往部分專家指出，全球暖化對寒冷氣候城市有正面影響，因當地居民可節省暖氣，但參與撰寫論文的埃斯特拉達（Francisco Estrada）指出，這種優勢（advantage）會隨着氣溫不斷攀升而消失。
"Heat island" makes cities hotter as century closes
【譯文】A group of scientists have published an analysis in the journal Nature Climate Change recently, saying that big cities suffered from "heat island effect" would be the major victims of climate change, in which megacities with high population density would become warmer by 7℃ or more by the end of this century, bringing about negative impacts on the urban life of city dwellers and great economic losses.
The professionals suggested taking measures such as painting the roads and roofs white, having widespread tree-planting and the like to reduce urban warming.
Air-con amplifies heating effect
Urbanization would inevitably lead to the change of natural landscape, such as replacing vegetation and water by the heat-trapping asphalt pavements and concrete buildings.
It was found that temperatures of black rooftops can reach as high as 88℃ if the temperature is 38℃. Waste heat from vehicles and air-conditioners would also push up air temperatures.
Therefore, temperatures in urban areas are often much higher than that in rural areas, resulting in the heat island effect.
Moreover, the use of air-conditioning for cooling intensifies the effect and also increases energy consumption. It was predicted that global warming would bring about economic costs and the total cumulative losses of the worst-off city could even reach 10.9% of GDP by 2100.
White asphalt would dispel heat
The black asphalt pavements in cities are often heat-absorbing. The experts suggested painting them and the roofs in white or other lighter colors that can reflect heat, as well as expanding vegetation to reduce the heat island effect.
Taking London as an example, downtown temperatures are usually 4℃ higher. But if the government implements all of the above-mentioned measures, temperatures would decrease by 2℃. Even by transforming just 20% of the city's pavements and buildings into less heat-trapping forms can reduce the air temperatures by about 0.8℃ and save up to 12 times the costs for installation and maintenance in the long run.
The co-author Richard Tol, a professor at the University of Sussex, said that much emphasis was put on tackling global climate change but the importance of local interventions was underestimated.
The professionals believed that the aforementioned local measures, albeit not being helpful in reducing global warming, would greatly benefit our daily life and eliminate some of the negative impacts, to a certain extent.
Some previous studies have suggested that cities in colder climates might benefit from global warming because of lower winter heating costs. But the lead author Francisco Estrada argued that such advantage would probably disappear as temperatures keep rising.■龐嘉儀
Q&A
1. 為應對全球暖化，世界各國於2015年聯合國氣候峰會（2015 United Nations Climate Change Conference）中簽訂了什麼協議？
2. 承上題，該協議對全球氣溫訂立了什麼目標？
3. 該協議由多少個國家共同簽訂？
4. 該協議取代了以前哪份協議書？
5. 最近哪個國家宣佈將退出該協議？
1.《巴黎協定》（Paris Agreement）
2. 把全球平均氣溫升幅控制在工業革命前水平以上低於2℃以內
3. 195個
4. 《京都議定書》（Kyoto Protocol）
5. 美國
