By Jon Wertheim And Black high school players are disproportionately affected. Welcome to SI Climate, our new ongoing series about how sports are adapting to—and affecting—our changing world. Before the Friday-night lights of the fall, there is the weekday afternoon heat of the summer. Scorching, oppressive days of merciless, withering triple-digit temperatures that come accessorized with carpets of humidity. It makes for the kind of conditions that are singularly ill-suited for running around outdoors, never mind doing so while wearing an insulated helmet, and wreathed in a 20-pound carapace …