内容来源：分享美国 地址链接：http://t.cn/RAoPf6r

美国的地方政府善于利用创新性的环保政策。

地方政府的优势之一在于它们没有州或联邦政府那么多的繁文缛节；优势之二在于它们贴近那些在城市中生活和经营的居民和企业；优势之三在于它们能够迅速对能源规章产生影响，而这些规章是建筑规范、交通运输及废物处理方式的组成部分，能对温室气体排放产生影响。

由于上述原因，美国各个城市已成为推行创新性政策的试点，以减轻气候变化、逆转环境退化以及支持使用可替代性能源。美国联邦制度的特性使城市的创新性政策往往能被州政府及联邦政府采纳，将城市置于环保运动的核心地位。【请见相关文章：欧巴马总统认为气候变化对我们构成的威胁最大、北极冰层消融危及北极动物的生存、美国风力发电前景光明】

楼顶绿地

2001年，芝加哥率先在11层高的市政厅（市政府办公楼）楼顶上开辟了一块绿地，过去楼顶上的温度在炎热的日子往往会飙升。如今，楼顶绿地上的植物能够反射热量并提供树荫，使楼顶上的温度降低了一半。市政厅的年度能源费用也因此减少了近1万美元。

今天，芝加哥的高层楼顶绿地面积已达41万8千平方米。楼顶花园能够再利用雨水，并能减少空气污染。芝加哥拥有120多座环境可持续性建筑，很多建筑楼顶上都有绿地，让该市在全美引领绿色建筑之风。




Cities as policy labs: Chicago’s rooftop experiment

U.S. local governments are well-positioned to experiment with innovative environmental policies.

For one thing, they are less bureaucratic than the larger state or federal governments. For another, they are close to the people and businesses who live and operate in cities. And finally, local governments can quickly influence energy regulations that are part of building codes, transit operations or waste disposal methods, all of which affect greenhouse gas emissions.

For these reasons, American cities have become laboratories for novel policies to reduce climate change, reverse environment degradation and support alternative energy. Due to the nature of the U.S. federal system, cities’ innovative policies are often adopted at the state or national level, putting cities at the center of the environmental movement.

Elevated greens

In 2001, Chicago pioneered a rooftop garden atop its 11-story City Hall (the seat of government), where the temperature on the roof used to spike on hot days. Now, with the garden’s plants reflecting heat and providing shade, the roof’s temperature has been cut by half. Consequently, City Hall’s annual power bill has dropped by almost $10,000.

Today, Chicago boasts 418,000 square meters of high-rise greenery. Rooftop gardens reuse rainwater and capture some airborne pollutants. With more than 120 environmentally sustainable buildings, many with green roofs, Chicago’s skyline is a national leader in green buildings.