of the humid continental climate throughout most of the country, except for the tundra and the extreme southwest. Mountain ranges in the south and east obstruct the flow of warm air masses from the Indian and Pacific oceans, while the European Plain spanning its west and north opens it to influence from the Atlantic and Arctic oceans. Most of northwest Russia and Siberia have a subarctic climate, with extremely severe winters in the inner regions of northeast Siberia (mostly Sakha, where the Northern Pole of Cold is located with the record low temperature of ), and more moderate winters elsewhere. Russia's vast coastline along the Arctic Ocean and the Russian Arctic islands have a polar climate. The coastal part of Krasnodar Krai on the Black Sea, most notably Sochi, and some coastal and interior strips of the North Caucasus possess a humid subtropical climate with mild and wet winters. In many regions of East Siberia and the Russian Far East, winter is dry compared to summer; while other parts of the country experience more even precipitation across seasons. Winter precipitation in most parts of the country usually falls as snow. The westernmost parts of Kaliningrad Oblast and some parts in the south of Krasnodar Krai and the North Caucasus have an oceanic climate. The region along the Lower Volga and Caspian Sea coast, as well as some southernmost slivers of Siberia, possess a semi-arid climate. Throughout much of the territory, there are only two distinct seasons, winter and summer; as spring and autumn are usually brief periods of change between extremely low and extremely high temperatures. The coldest month is January (February on the coastline); the warmest is usually July. Great ranges of temperature are typical. In winter, temperatures get colder both from south to north and from west to east. Summers can be quite hot, even in Siberia. Climate change in Russia is causing more frequent wildfires, and thawing the country's large expanse of permafrost. Biodiversity Russia, owing to its gigantic size, has diverse ecosystems, including polar deserts, tundra, forest tundra, taiga, mixed and broadleaf forest, forest steppe, steppe, semi-desert, and subtropics. About half of Russia's territory is forested, and it has the world's largest area of forest, which sequester some of the world's highest amounts of carbon dioxide. Russian biodiversity includes 12,500 species of vascular plants, 2,200 species of bryophytes, about 3,000 species of lichens, 7,000–9,000 species of