Physical Geography
Permafrost
Permafrost is ground that stays at or below 0C for at least 2 consecutive years. It covers about 25% of Northern Hemisphere land area, primarily in Russia (65% of territory), Canada (50%), and Alaska (80%).
Permafrost depth varies by region, exceeding 1,500m in northern Siberia. Infrastructure built on permafrost (roads, buildings, pipelines) faces serious damage risks from climate-driven thawing. Norilsk and Yakutsk in Russia are major cities built on permafrost.
Most territory is permafrost suggests Russia, Canada, or USA (Alaska). Permafrost cities + Asia narrows to Russia (Siberia).