palsa

A palsa is a type of mound or hill found primarily in cold, high-latitude regions, especially within subarctic and tundra environments. These formations are characterized by their core of ice or frozen peat, surrounded by a layer of well-drained, unfrozen soil. Typically, palsas range from a few centimeters to several meters in height and have a conical or dome-shaped appearance.

Palsas develop through a combination of climatic and hydrological conditions. During winter, the ground freezes to considerable depths, forming a permafrost layer. In summer, surface layers thaw, but the core remains frozen due to insulation by the overlying peat or soil. Over time, this process causes the formation of a permafrost core that resists melting, creating the mound structure. The presence of snow cover and well-drained substrates are critical factors in palsa development.

These features play a significant role in the Arctic and subarctic ecosystems. They influence local hydrology, providing microhabitats for specialized flora and fauna. Palsas also serve as indicators of climate change; their abundance and stability are sensitive to warming temperatures, which may lead to their degradation or collapse.

Palsas are primarily found in regions such as northern Scandinavia, Siberia, Canada, and Greenland. The word "palsa" originates from Finnish and is widely used in Scandinavian countries to describe these thawed, permafrost-formed features. Their study offers insights into permafrost dynamics, climate change impacts, and Arctic ecology.

In summary, palsas are frozen mounds formed by permafrost processes, serving as important ecological indicators and features in cold-region landscapes.