n a recent drizzly, cold Saturday, a climate scientist named Gisela Winckler was standing at Beach Ninety-fourth Street, in Rockaway, Queens. The ocean behind her was gray-green, uninviting, confused, the wind blowing hard onshore. A flock of surfers bobbed in the waves, a scattering of people strolled. Next to her, a huge black-and-orange L.E.D. roadwork sign flashed a series of messages: “climate denial kills”; “abolish coal onialism”; “vote eco logically.” “I thought we would be getting a lot more questions, actually, about these specific messages,” Winckler said. “This one, for example, is pretty complicated.” The L.E.D. sign read “human agenda ahead.”