Sea levels may be rising, but North America’s Great Lakes are suffering from just the opposite problem: their water levels have been falling for the last decade and a half. Borne of glacial melt – but now at the mercy of the skies for most of their nourishment – the Great Lakes have been hit hard by shorter winters and warmer summers. Water temperatures and evaporation rates have increased, while water levels have remained below average for more than 14 years.

‘We have not seen anything like this in our recorded history,’ Frank Quinn, an emeritus hydrologist with National Oceanic and Atmospheric Administration, told the Milwaukee Journal Sentinal earlier this year.

The shrinking of the world’s largest freshwater resource – and a key shipping route for international exports from the US – is already taking its toll on the $34bn Great Lakes shipping industry, which transports more than 160m tons of cargo annually. Fear of running aground is forcing ships to lighten their loads, which raises costs for shippers, steel mills, car manufacturers, utilities and more, ultimately hitting consumers.

‘At the end of the day, it causes a lot of inefficiencies,’ said Mark Barker, president of The Interlake Steamship Co, one of the […]