The nonprofit Lexington Global Warming Action Coalition will host a public forum from 7 to 9 p.m. Sunday to explore what can be done at the local, state, and federal levels to counter climate change. The discussion, called “It’s High Time . . . Climate Change Solutions,” will take place in Cary Memorial Hall, 1605 Massachusetts Ave. Anne L. Kelly, who directs the Ceres Coalition’s Business for Innovative Climate & Energy Policy project, will moderate a panel discussion featuring Tim Smith of Walden Asset Management; Shanna Cleveland, with the Conservation Law Foundation; Larry Chretie, executive director of the Massachusetts Energy Consumers Alliance; and Sonia DeMarta, founder of the Lexington Farmers’ Market.