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The tundra was divided into different classes depending on the temperature and precipitation in accordance with the Holdridge classification. Dry, moist, wet, and rainy tundras were distinguished. Datasets on climate variability were obtained from the Climatic Research Unit website (http://www.cru.uea.ac.uk/data) for the period from 2001 to 2017. The long-term (2001–2016) dynamics of phytomass for different tundra classes was studied on the basis of the Normalized Differential Vegetation Index (NDVI). The positive long-term dynamics of NDVI-vegetation for the tundra classes studied was revealed. This trend correlates with the positive dynamics of the mean annual biotemperature. It was shown that the impact of global climate change on vegetation of different tundra classes is ambiguous. For the dry tundra, the increase in NDVI in May and June was higher than for the rainy tundra. This correlates with the fact that the increase in the mean monthly temperatures in May and June on the territory of the dry tundra is greater than on the territory of the rainy tundra. [ABSTRACT FROM AUTHOR]

Abstract: Laboratory experiments were conducted in a hermetically sealed growth chamber with two soil samples obtained from the arctic tundra zone with different levels of moisture. Samples were maintained at a growing season typical of the region from which they were taken, and for the sample with a high level of moisture it was made twice: with the temperature in accord with natural conditions and one increased by 2°C. It has been shown that heating of the overmoistened tundra soil by 2°C can increased the average carbon dioxide emissions by almost two times (from 75 to 100-150 mg m-2 h-1). Upon the application of heat, no significant increase in methane emission was observed. [ABSTRACT FROM AUTHOR]