ABC News: The "go green" mantra is trumpeted throughout the nation’s cities and towns as they try to deal with climate change on a local level. Big cities, like New York, and smaller ones, like Greensburg, Kan., have made strides toward making their communities more eco-friendly. Check out how the following cities are helping residents become more green about their thinking. New York City Amid the city’s steel and concrete oasis lies a neighborhood at the southernmost tip of …