Awrinkle of tide is creeping up the lugworm-stippled beach. If I half-close my eyes, sand and sea are a single hazy surface, which skylines the Isle of Man in the distance. I’m at Mill Quarter Bay, whose name hints at undercurrents that belie the calm. Indeed, this place was once crowded with mills harnessing the tide as it churned through the Narrows of Strangford Lough. Other clues to what has carved the area remain: the Angus Rock lighthouse; the markers and buoys dotting the waters; the brick-red of the low cliffs. I make my way across seaweed-tasselled rocks towards the cliffs. Bearded drapes of sward hang down to the gaping pockmarks of sand martin nest-burrows. A fence braces against an impending slide. The face reveals shifts not just of water but of ice. This is glacial till, mixed with the soft clay of a former seabed. Killard’s peninsula is cherished locally for its butterfly-garlanded wildflowers. However, its national importance rests on its account of the disintegration of the last great ice-sheet that froze all of Ireland and most of Britain during the late Pleistocene. I continue. An eroded path leads to a scruffy meadow of coarse grasses laced with wild carrot and dabbed with the purples of scabious and knapweed. If sea levels were the same as when this moraine was shoved into shape, I could traipse across to the Bride Hills on the Isle of Man, and make it to St Bees in Cumbria. But there was a tipping point that changed everything: the rapid melt of the glacial hinterland. Along Killard’s axis, the topography and sediments describe how herds of icebergs were calved into a warming sea, leaving behind many drumlins and a new coastline. Nearing the rocky headland that reputedly shipwrecked St Patrick, my stride breaks. I crouch. It’s a garden tiger moth, a species that favours cooler climates. The gaudy tatter takes my mind back to the summer’s record-breaking heatwave; the subsequent deluges; the looming shadow of the Intergovernmental Panel on Climate Change report. And I don’t know whether to be heartened by this moth’s recent life or disturbed by its crisp remnant.