BY Ariel Schwartz

Many major cities have seen a decline in driving over the past few years. The reasons for this are varied, but if it's a continuing trend, it's going to mean drastic changes for the way we shape our cities.

Our cities play a vital role in the quest to achieve global ecological sustainability. They are the largest contributors to greenhouse gases and climate change. However, if we can achieve sustainable construction and use of urban infrastructure, our cities could become a critical leverage point in global efforts to drastically reduce emissions and avoid the social and economic costs associated with climate change, as well as enhance energy security and resilience in the face of high fossil energy prices.