Thawing permafrost is roiling the Arctic landscape, driven by a hidden world of changes beneath the surface as the climate warms

Permafrost and ice wedges have built up over millennia in the Arctic. When they thaw, they destabilize the surrounding landscape. Michael Robinson Chavez/The Washington Post via Getty Images

Across the Arctic, strange things are happening to the landscape.

Massive lakes, several square miles in size, have disappeared in the span of a few days. Hillsides slump. Ice-rich ground collapses, leaving the landscape wavy where it once was flat, and in some locations creating vast fields of large, sunken polygons.