Climate change has emerged as one of the most important environmental issues we are facing. Sprawling development is a major contributor to greenhouse gas emissions because it is automobile dependent. A recent California study showed that "More compact development patterns, along with more efficient cars and buildings, cleaner fuels, and a cleaner energy portfolio are all essential in reducing greenhouse gas emissions. The Growing Smart scenario prevents the release of 70 million metric tons of carbon dioxide equivalent in 2050, or 25% less than a Business as Usual future."