permafrost
n. uncountable C1 Advanced UK //pˈɜːmɐfɹˌɒst// per·mafrost
n. soil, rock, or sand that stays frozen for at least two years. It is found in very cold places like the Arctic and Antarctica.
n. ground that remains frozen for two or more consecutive years. It consists of soil, rock, or sediment that remains below 0°C for extended periods.
The melting of permafrost can cause the ground to sink.
Scientists are studying how the thawing of permafrost in Siberia releases large amounts of methane into the atmosphere.
The structural integrity of many northern communities is directly tied to the stability of the permafrost, which is increasingly vulnerable to the rapid warming of the polar regions.
From perma- + frost.