Europe's rivers are drying up. Can they be saved?

A drought and extreme summer heat have caused water levels on the Rhine, Danube and Loire rivers to drop to historic lows, exposing sunken World War II-era wreckage and disrupting shipping and other activities. On the Danube, near the Serbian and Romanian border, the hulls of dozens of German warships from World War II have surfaced, along with unexploded ordnance and a military motorcycle, some vessels reportedly still carrying weapons. In Romania, the remains of an ancient mammoth were also uncovered as river levels fell. In Germany, fishing boats have become stranded near the banks of the Rhine, while sections of the Loire riverbed in France are partially dry. The low water levels are also raising concerns about impacts on agriculture, ecosystems and future drinking water supplies.