Permafrost

Permanently frozen ground (soil, sediment, or rock) that has remained at or below 0°C for at least two consecutive years, covering approximately 15 million km² or roughly 11% of Earth's land surface, concentrated in the Arctic, sub-Arctic, and high-mountain regions such as the Tibetan Plateau. Permafrost stores an estimated 1,500 billion tonnes of organic carbon (twice the current atmospheric carbon stock), and its thawing due to climate change releases CO₂ and methane, creating a positive feedback loop of further warming. For India, Himalayan permafrost degradation destabilises slopes, endangers infrastructure, and threatens high-altitude freshwater recharge.