After a summer of record-breaking heat, vast swaths of the United States are now grappling with extreme cold as a brutal Arctic blast brings snow squalls, deadly ice and life-threatening wind chills. As unprecedented heat makes way for cold, it can provide fuel for climate-change deniers who point to freezing temperatures as evidence that global warming is overstated. But scientists are clear: cold extremes will still occur even as winters warm overall. Global heat records outpace cold records — 2023 was the hottest year on record by a huge margin. And even as the US struggles to cope with intense...