PlaNYC, New York's ambitious sustainability plan for the next two decades, turned two years old on Earth Day 2009. To commemorate, former Deputy Mayor and PlaNYC mastermind Daniel Doctoroff took part in a panel discussion about urban planning at the Museum of the City of New York.

New Yorkers can breathe easier than most of the country; our carbon footprints are smaller than any other metropolitan center. But despite improvements in the quality of life since the 1970s, the city faces significant challenges in the future, with an aging infrastructure and a population that is expected to swell to nine million in 2030.

On Earth Day 2007, Mayor Bloomberg unveiled the city’s master plan to address housing, open space, water quality, congestion, air quality — even child obesity rates — for the 21st century.

To mark the plan’s two-year anniversary, former Deputy Mayor and PlaNYC mastermind Daniel Doctoroff took part in a discussion on urban planning at the Museum of the City of New York with NYU professors Thomas Bender (author of The Unfinished City: New York and the Metropolitan Idea) and Hilary Ballon (author of Robert Moses and the Modern City: The Transformation of New York).

More: If you’re interested in urban planning, sustainability or keeping an eye on your government at work, you can download or read the entire PlaNYC report by right-clicking here.