Thermokarst is a type of landform that occurs when permafrost, or permanently frozen ground, begins to thaw. This process can create uneven ground, depressions, and ponds as the ice within the soil melts. The melting ice causes the ground to settle and can lead to significant changes in the landscape. The formation of thermokarst is often accelerated by climate change, which raises temperatures and increases the rate of permafrost thawing. This phenomenon can impact ecosystems, as it alters habitats for plants and animals, and can also affect human infrastructure in areas like the Arctic and subarctic regions.