Green spaces within cities can cut down on pollution, add biodiversity, and fight global warming. Public libraries can promote green spaces in an urban setting in different ways. They can have programs and materials available to patrons, provide a seed bank and environmental library of things, be a green building and have diverse native plants on the property, and encourage residents to plant a range of plants in their yards. Libraries can provide a space for officials and the public to meet together and discuss when and where to plant the green spaces or convert unused or underutilized land into green spaces.