Based in Cambridge, MA, Carbonrally is a web platform offering individuals and groups a fun, simple and social way to conserve energy and have a measurable impact on climate change. Carbonrally publishes periodic science-based “challenges” which involve personal changes in behavior. The site enumerates the personal CO2 impacts associated with the challenges, and also reports combined scores for teams and the entire community. Through team play, Carbonrally provides a quick and easy program to engage people in collective energy and climate action. The service is free and available to participants 13 years and older.