Arctic ecology is the scientific study of the relationships between biotic and abiotic factors in the arctic, the region north of the Arctic Circle (66 33’). This region is characterized by stressful conditions as a result of extreme cold, low precipitation, a limited growing season (50–90 days) and virtually no sunlight throughout the winter. The Arctic consists of taiga (or boreal forest) and tundra biomes, which also dominate very high elevations, even in the tropics. Sensitive ecosystems exist throughout the Arctic region, which are being impacted dramatically by global warming.