A new report from Transportation Alternatives comparing carbon emissions for NYC transportation modes finds that drivers account for 60 percent of the city’s transportation-related CO₂, while accounting for just 31 percent of all commuting trips.

"Rolling Carbon: Greenhouse Gas Emissions from Commuting in New York City" [PDF] reveals that the average New York City commute generates about seven pounds of carbon dioxide per round-trip, for a total of 1,750 pounds of CO₂ annually. Though this ranks us among the "greenest" US commuters in the aggregate, the report notes that individual impacts vary widely, depending on mode and distance. To that end, "Rolling Carbon" breaks down per-mile emissions for public and private conveyance, from Escalades, taxicabs and Priuses to trains, buses and, of course, bikes and feet.

Other report findings include:

• Driving alone causes the emission of about five times the amount of CO₂ (over 4,000 pounds per year) as is caused by taking the subway (about 820 pounds per year).
• If just 5% of all people commuting by private car or taxi switched to transit, walking or cycling, the result would be a decrease of 150 million pounds of CO2 emissions per year — the equivalent of planting trees on an area 1.3 times the size of Manhattan.

Accompanying the report is a new killer app: RollingCarbon.org features a personalized Carbon Calculator for New Yorkers to determine emission levels generated by their commutes, and how many annual tree plantings would be needed to offset the trip. As illustrated by the chart above, pedestrians, cyclists and skaters are in the clear.