New York's Metropolitan Transportation Authority (MTA) announced its operations reduced the carbon dioxide and other greenhouse gas emissions of the region by 17.1 million metric tons in 2011. With 8.5 million riders per average weekday, that means each trip on a train or bus prevents the emission of 10 pounds of greenhouse gases, on average, compared with making that trip by car.

Different trips conserve different amounts of greenhouse gases. Electric-powered trains produce lower emissions than diesel-powered buses, and the longer the trip and the more congestion one would encounter by driving, the greater the carbon savings. Here are samples of the carbon avoidance of specific MTA trips:

•    A 27-mile trip from Tarrytown to Grand Central Terminal on Metro-North Railroad prevents emission of 19.7 pounds of carbon dioxide/equivalent (CO2e).
•    A 25-mile trip from Bensonhurst to the Bronx Zoo on the New York City Subway prevents emission of 21.9 pounds of CO2e.
•    An 8.3-mile trip from West 106th Street to LaGuardia Airport on the M60 bus prevents emission of 3.3 pounds of CO2e.

The MTA developed mode-specific PSA videos of children speaking about the importance of protecting the environment by using public transportation, including the system's subway, bus, Long Island Rail Road and the Metro-North Railroad.

The MTA determines its greenhouse gas emissions using a protocol established by The Climate Registry, a non-profit organization that measures the carbon footprints of companies and government bodies. The figures are fully audited by an independent greenhouse gas verifier, LRQA Americas Sustainability Inc. Estimates of avoided greenhouse gas emissions are developed following guidance from the American Public Transportation Association.

The MTA carefully quantifies its greenhouse gas emissions for all its facilities, vehicles, and operations, and factors those numbers into its per-trip carbon savings calculations. In 2011, the MTA released a total of 2.09 million metric tons of CO2 equivalent through its operations, which is 103,647 fewer metric tons than the prior year.

Nearly 80% of the MTA’s greenhouse gas emissions result from generating the electricity that powers subways and commuter trains, as well as burning fuel — largely CNG and ultra-low sulfur diesel — in buses and diesel commuter trains. Only 20% of the emissions come from “behind-the-scenes” operations, like maintenance facilities or offices.