Climate Central: Researchers have found a "mega canyon" in Greenland tucked under a mile and a half of ice that could rival the size and depth of Arizona's Grand Canyon. While the discovery won't become a major tourist attraction, it does provide insight into how meltwater courses its way underneath the world's second-largest ice sheet, and how that might affect ice shelves and glaciers at its periphery. Melting ice from Greenland and Antarctica is now the dominant contributor to global sea level rise, which is expected...