@cbsnews: Water levels on the Danube River have dropped so low that the remains of an ancient woolly mammoth — and dozens of World War II German warships — are emerging into view. Extreme heat and prolonged drought have pushed the Danube, Europe's second-longest river, to record-low levels, exposing pieces of history that had remained hidden beneath the river for decades. The record-low water levels have also brought some power plants to the brink of shutting down. #danube #danuberiver #budapest #hungary #climate