The weather and climate of the Arctic have produced one of the most inhospitable and extreme environments on Earth, characterized by limited sunlight for much of the year, extreme temperature variations, and a short growing season. The Arctic is often defined by climatic parameters, for example, as the area where the average temperature for the warmest month is below 10°C (50°F). Sea ice, snow cover, glaciers, tundra, permafrost, boreal forests, and peatlands are expressions of this severe climate, as well as being sensitive indicators of climatic change. Their presence and extent are susceptible to subtle variations in sunlight, surface temperature, and heat transport through the atmosphere and ocean.

The Arctic also plays an important role in the complex interactions of the Earth's system. The mean global circulation patterns of the atmosphere and ocean are controlled by equator-pole temperature differences. Polar feedback processes affect the global climate, and global warming, due in large part to greenhouse gas emissions, amplifies this effect at high latitudes. The Arctic climate is thus governed by many complex interactions, which are part of the global climate system, and, in turn, climatic conditions shape much of the Arctic environment. This article attempts to provide a general picture of the Arctic climate, the processes controlling it, present climatic trends, past variability, and predictions of future climates, including greenhouse warming.

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