LONGMEADOW — Students, teachers, community members and vendors will gather on Saturday from 11 a.m. to 3 p.m. at the town green for the Future Planet Fiesta and the Cooler Communities Climate Fair, a day celebrating student-led climate learning and local climate solutions.The event will showcase student projects exploring climate science, energy efficiency, and community solutions. Students from the Center School and the Longmeadow High School C…