evidence: Since the early 2000s, Thwaites, also known as the "Doomsday Glacier," has dumped a trillion tons of ice into the sea. Scientists like Scambos believe it may be in the early stages of an irreversible collapse, which could take out a large portion of the West Antarctic ice sheet, raising global sea levels by at least 2 feet, and perhaps more than 10. [...] Warm ocean water is weakening the undersides of the floating ice shelves that support Thwaites. [...] While East Antarctica’s deep-rooted glaciers "seem to be further away from reaching the tipping point for now," as Scambos puts it, continued ocean warming and circulation of warm, deep water beneath their protective ice shelves could eventually destabilize them. A 2014 modeling paper found that removing a comparably small "plug" of ice from the shelf buttressing the Wilkes Basin — equivalent to just 3 inches of sea-level rise — could be enough to tip off a runaway collapse that adds up to 13 feet to global sea levels. Recent airborne and satellite remote sensing surveys, meanwhile, reveal that both Totten and Denman Glaciers are already retreating at their grounding lines. The collapse of Totten would add the equivalent of another 13 feet of sea-level rise; Denman would add another 5.