From the air, the evidence of climate change is striking

The airport in Greenland's capital, Nuuk, doesn't look like any other airport. Outside, the tiny runway accommodates a lone helicopter. Inside the waiting room, the chairs are upholstered in seal skin.

This otherworldliness was expected, as Greenland has little in common with any other place on the planet. The largest island in the world, it is weighed down by its immense ice cap that in winter covers almost its entire land mass. In summer, the ice retreats to reveal a savage landscape of fjords and jagged rocks. And, at the end of this summer, it has revealed more than ever.

Flying low, fast and north into the interior, the mind's eye expects a scene of endless winter but the reality is worryingly different. There is little to prepare you for the summer spectacle of Greenland's fjords. It feels like a confusion of geography. At once as familiar as Scottish lochs, they present a problem of scale. The dark mountains that frame the deep lakes rise so high that they push through the cloud clover and on to snow caps that are rarely if ever seen from the shore. And then there are the icebergs, floating in brilliant white squadrons, trailing pale tails of melt water for miles behind.

But on the shore this is now a genuinely green land. One where Arctic barley, radishes and potatoes are growing for the first time in centuries.

The remote outpost of Kapisillit, Greenlandic for salmon, is testament to the speed of these changes. Seen from the air, the settlement has a defensive aspect, its largely windowless wooden houses, home to fewer than 80 people, seem to huddle together. But in bright sunshine the defence seems pointless and the light instead catches the primary colours that the houses are painted to cheer the dark days and nights of winter.

At the far end of Nuuk's fjord, flying through a rock canyon barely the width of a helicopter blade, we are confronted with the first sight of the glaciers. The ice that fills an entire valley is majestic. The force of the glacier has carved the earth itself and wrinkled the slopes of the mountains. The violence of its movement is visible on the cracked surface of the glacier where the ice rises like thousands of sheets of broken glass all stood on edge.

Even this far inland, in this changed climate, we are witnessing a dying glacier. Separated by the rising temperatures from its source on the ice cap, it is collapsing at extraordinary speed, feeding roaring rivers which in turn pour into the fjords beyond. The spectacle is both beautiful and wrong.

Glacial ice does not look like any other ice. It is a haunting blue, as its density absorbs every other colour of the spectrum. That density itself is a product of its age and the large ice crystals that scatter blue light to incredible effect.

This natural show of light and colour is seen to best effect in the collapsing ice caves that stud the disintegrating tongue of the glacier. Hollowed out from below by melt water, these holes, large enough to fly a helicopter into, form perfect expanding circles, with spiralling blue canals that carry pools of water from the glacier's surface and out, eventually, into the rising seas beyond.