Cambridge has declared itself a green community that is responding to a climate emergency, but Portsmouth, N.H., has gone further: The city declared itself an “Eco-Municipality” all the way back in November 2007.

John Bohenko, Portsmouth’s city manager, and Peter Britz, its sustainability coordinator and environmental planner, are set to speak at 7 p.m. Wednesday on their city council’s resolution and ongoing approach to sustainability, said Cambridge city councillor and vice mayor Henrietta Davis, a sponsor of the event.

Sarah James, of the Institute for Eco-Municipality Education & Assistance, is also schedule to talk, with a brief introduction to the concept of eco-municipalities, which focuses on four principles:

• Reducing dependence on fossil fuels, underground metals and minerals.
• Reducing dependence on synthetic chemicals and other unnatural substances.
• Reducing encroachment on nature.
• Meeting human needs fairly and efficiently.

Other sponsors of the event are the Cambridge Energy Alliance and Cambridge Renewable Energy Team.

The event is planned for the auditorium of Cambridge’s Main Library, 449 Broadway. For information, call (617) 349-4205. An event looking at Gov. Deval Patrick’s plan to cut greenhouse gas emissions in the state follows March 29; the details are here.

This post was based on a press release.