A. Permanent Arctic darkness
B. Sudden sea-ice formation
C. A period when soil stays near freezing
D. Complete melting of Arctic soil
NASA researchers reported in August 2026 on the Arctic “zero curtain,” a period during which ground temperatures can remain close to the freezing point for days or even weeks as autumn changes into winter.
This happens because energy released during the freezing of water in the soil slows further temperature decline. Understanding this process is important for studying permafrost and Arctic climate change.