can run hot and cold with windchills below zero on the rio grande, nearly 10 million lost power. the february blast became america's costliest winter storm event ever. at number eight, flash floods on three continue innocents. in germany and belgium, modern-day warning systems failed as a month of rain fell in one day. in china, commuters clung to the ceiling of a subway as a thousand-year flood hit a province. back in the u.s., the deadliest flood in tennessee came like a tidal wave. at number seven, u.s. rejoins the paris climate accord hours after joe biden became president. but pledging to splash planet-cooking pollution by half this decade is one thing. convincing congress to take bold action is another. at number six, a code red for humanity as scientists around the world issue their most dire