Deep beneath the windswept, snow-crusted expanses of the Scandinavian high Arctic, a clandestine world pulses with life. While the surface of the tundra may appear barren during the harsh winter months, a complex network of tunnels and runways exists just centimeters below the frost line. Here, the Norway lemming, a small but ecologically pivotal rodent, orchestrates a subterranean existence that serves as the bedrock for one of the world's most resilient Arctic ecosystems. The Architecture of the Under-Snow Realm The Norway lemming (Lemmus lemmus) is not merely a resident of the tundra; it is a master engineer of the subnivean zone—the narrow, insulating space between the frozen soil and the heavy winter snowpack. By constructing intricate labyrinths of tunnels, these rodents maintain a microclimate that remains significantly warmer than the brutal sub-zero air temperatures above. This behavior is crucial for survival, allowing the lemmings to forage on mosses and grasses throu...