Cities have a very significant impact on climate change: It’s estimated that urban areas are responsible for 75 percent of greenhouse gas emissions. Before the climate conference in Paris in December, developed and developing nations alike pledged to curb greenhouse-gas emissions in an effort to reach worldwide consensus. A healthy city is an integrated structure of life, work and movement. It requires urban design that respects the land and the area’s ecosystem: the topography, bodies of water and vegetation. This design guides investments made by the public and private sectors and must involve the intelligent use of density, compactness and a mixture of uses and income levels. One way to build a sustainable city is to plant many plants to absorb any of the carbon emitted into the atmosphere. Cities could be more compact so that not a lot of transportation is necessary to get to one place to another. If any transportation is necessary, it would be public transportation because that is more efficeint and sustainable for a city. There would also be more bike lanes so that  biking would be an option. It may take a lot to achieve all of this or even some of it but it would be worth it in the end because there wouldn't be as much greenhouse gases in the atmosphere as there are now.