Mesa currently is a visiting professor at SciencesPo, an international research university in Paris. From 2012 to 2014, she served as director of the New York City Mayor's Office of Sustainability and was chief administrative officer at the Columbia Journalism School. Previously, she served in environmental leadership roles at the White House Council on Environmental Quality, the U.S. Air Force, the U.S. Environmental Protection Agency, and the California Attorney General's office.