What's the greenest place in America? If you answered something like the warm sunlight of Santa Barbara, you'd be wrong. The greenest place in America has almost no sign of nature-- the buildings outnumber the trees-- and the air isn't all that great. What it has is density and efficiency-- the twin qualities that finally define green in the global warming time. Applying those standards,the greenest place in America is New York City-- particularly,the overcrowded,overpriced island of Manhattan, which produces 30% less per-capita greenhouse gas than that of the nation. It's that density that makes Manhattan so green. Manhattan's population density is 800 times the national average. Density comes with negatives,certainly-- small living spaces,air pollution-- but it also enables amazing efficiencies.Over 80% of Manhattanites travel to work by public transport, by bike or on foot-- compared to an average of about 8% everywhere else in the country. Manhattan's apartment buildings are far more energy-efficient than the houses in the suburbs. What's true of New York City is more or less true of other American urban areas, which explains why a growing part of the environmental movement now focuses on greening cities, hoping to attract more Americans back downtown. There's an effort to make cities more sustainable ,by improving public transport,reducing air pollution and upgrading energy efficiency. But even more important, it is quite urgent to change decades of government policies that have been in favor of the suburbs,with disastrous consequences for energy,the environment and the climate. That's exactly the difficult point. For all the high efficiency and convenience and richness of living in a city,there are disadvantages too.New York,for example,has some of the highest childhood asthma rates in the U.S. So it's welcome news that New York has continued to push its P1aNYC scheme, a long-term program to make the city greener and more sustainable over the next decades. Recently _ announced an update to the plan that includes _ heavy heating oils in New York City apartment buildings by 2030,to be replaced with cleaner natural gas. Manhattan is considered as the greenest place in America because of its  _
buildings and trees density and efficiency sunlight and nature transport and population