One of the first individuals to arouse concern about the impact that modern society was having on the environment was Rachel Carson in her book "Silent Spring." In her book, she described how chemicals such as DDT could have a cumulative negative impact that was not immediately recognized, and how we could use various animal species such as birds to predict the impact that chemicals would eventually have on humans. Meanwhile, in the 1970's, a group called the Club of Rome published a book titled "The Limits on Growth" that predicted some of the long-range negative impacts of increasing human population growth. The creation of the U.S. Environmental Protection Agency and the passage of various pollution control laws in the 1970's reflected the public's increasing awareness of the quality of the environment at that time. It is only recently, however, that the problems of global warming and climate change have caused the general public to be aware that the design and planning of our built-environment can either lock us into a pattern of energy wastefulness and pollution -- or can be part of the solution to increased energy conservation and pollution control. As a consequence, urban design and planning has come to the forefront of public policy in helping to find a way to a more sustainable future.