分析了美国几个城市过去100年的气温趋势。大约自1940年以来，城市气温总体上稳步上升。夏季月平均气温每十年上升0.25-1华氏度（洛杉矶等大城市约为1华氏度，小城市约为0.25华氏度）。没有证据表明这种上升正在放缓，当然，全球温室气体变暖也会增加类似的上升。城市的典型电力需求每上升一华氏度，就会增加峰值的1%到2%，大多数主要城市现在比20世纪初大约高出5华氏度。因此，我们估计当前城市电力需求的5%至10%用于冷却建筑物，以补偿热岛效应。 有一些策略可以缓解热岛效应。计算机模拟和实地研究量化了树木和较轻表面减少夏季热岛的潜力。结果表明，通过城市地区的绿化和增白，节约能源和避免二氧化碳的成本分别低于1美分/千瓦时和2美分/千克碳。关键词:气候、温度、城市地区、城市、成本、节能、能耗、美国、空调、制冷、树木、温室效应。引用:研讨会论文，佐治亚州亚特兰大，1990年

Temperature trends for the last 100 years in several U.S. cities were analysed. Since approximately 1940 there has been a steady overall increase in urban temperatures. Summer monthly averages have increased by 0.25-1 deg F per decade (approximately 1 deg F for larger cities like Los Angeles and 0.25 deg F for smaller cities). There is no evidence that this rise is moderating, and of course global greenhouse warming will add a comparable rise. Typical electric demand of cities increases by 1% to 2% of the peak for each deg F, and most major cities are now approximately 5 deg F warmer than they were in the early 1900s. Hence, we estimate that about 5% to 10% of the current urban electric demand is spent to cool buildings just to compensate for the heat island effect. There are some strategies that can alleviate the heat island effect. Computer simulations and field studies have quantified the potential of trees and lighter surfaces for reducing summer heat islands. Results indicate that the cost of saved energy and avoided CO2, through greening and whitening of urban areas, is less than 1 cent/kWh and 2 cent/kg of carbon, respectively.KEYWORDS: climate, temperature, urban areas, cities, costs, energy conservation, energy consumption, USA, air conditioning, cooling, trees, greenhouse effect.