While the very oldest ice has all but disappeared, there has been an increase in two - and three-year-old ice, which could potentially thicken and slow the decline at least for a while.

The team found that results from the two methods roughly matched and showed that Greenland is losing enough ice to contribute on average 0.46 millimetres per year to global sea-level rise.

Channels through the Canadian Arctic archipelago that were choked with ice at this time of year two decades ago are now expanses of open water or vast patchworks of tiny islands of melting ice.