Polaris, the North Star, is located almost directly above the North Pole. Around it are the stars that  form the constellation known as Ursa Major, the Great  Bear. The term Arctic comes from the ancient Greek  word Arktikós, the country of the Great Bear. 

Earth’s northern polar region consists of a vast ocean  surrounded by land, in contrast to the southern polar  region in which an ice-covered continent is surrounded  by ocean. Perhaps the most striking features are the snow  and ice that cover much of the arctic land and sea surface,  particularly in the high Arctic. And draped like a pair of great  green shawls over the shoulders of the two facing continents are  the boreal (meaning northern) forests. A wide expanse of tundra –  treeless plains over frozen ground – lies between the icy high north and the  forested sub-arctic.   

One line often used to define the region is the Arctic Circle, drawn at the latitude  north of which the sun does not rise above the horizon at winter solstice and does  not set below it at summer solstice – “the land of the midnight sun.” Other boundaries  used to define the Arctic include treeline, climatic boundaries, and permafrost  extent on land and sea-ice extent on the ocean. For the purposes of this  assessment, the boundary will be more flexible, also encompassing sub-arctic  areas integral to the functioning of the arctic system. 

High arctic lands and seas are home to an array of plants, animals, and people that  survive in some of the most extreme conditions on the planet. From the algae that  live on the underside of sea ice, to the polar bears that hunt on top of the ice, to  the indigenous human societies that have developed in close connection with their  environment, these communities are uniquely adapted to what many outside the  region would view as a very severe climate.   

Life in the Arctic has historically been both vulnerable and resilient. Factors that  contribute to the Arctic’s vulnerability include its relatively short growing season  and smaller variety of living things compared to temperate regions. In addition,  arctic climate is highly variable, and a sudden summer storm or freeze can wipe out  an entire generation of young birds, thousands of seal pups, or hundreds of caribou  calves. Yet some arctic species have also displayed remarkable resilience to historic  extremes, as evidenced by the recovery of populations that have occasionally been  decimated by climatic variations.

The increasingly rapid rate of recent climate change poses new challenges to the resilience of arctic life. In addition to the impacts of climate change, many other stresses brought about by human activities are simultaneously affecting life in the Arctic, including air and water contamination, overfishing, increasing levels of ultraviolet radiation due to ozone depletion, habitat alteration and pollution due to resource extraction, and increasing pressure on land and resources related to the growing human population in the region. The sum of these factors threatens to overwhelm the adaptive capacity of some arctic populations and ecosystems.

Polaris, the North Star, is located almost directly above the North Pole. Around it are the stars that  form the constellation known as Ursa Major, the Great  Bear. The term Arctic comes from the ancient Greek  word Arktikós, the country of the Great Bear. 

Earth’s northern polar region consists of a vast ocean  surrounded by land, in contrast to the southern polar  region in which an ice-covered continent is surrounded  by ocean. Perhaps the most striking features are the snow  and ice that cover much of the arctic land and sea surface,  particularly in the high Arctic. And draped like a pair of great  green shawls over the shoulders of the two facing continents are  the boreal (meaning northern) forests. A wide expanse of tundra –  treeless plains over frozen ground – lies between the icy high north and the  forested sub-arctic.   

One line often used to define the region is the Arctic Circle, drawn at the latitude  north of which the sun does not rise above the horizon at winter solstice and does  not set below it at summer solstice – “the land of the midnight sun.” Other boundaries  used to define the Arctic include treeline, climatic boundaries, and permafrost  extent on land and sea-ice extent on the ocean. For the purposes of this  assessment, the boundary will be more flexible, also encompassing sub-arctic  areas integral to the functioning of the arctic system. 

High arctic lands and seas are home to an array of plants, animals, and people that  survive in some of the most extreme conditions on the planet. From the algae that  live on the underside of sea ice, to the polar bears that hunt on top of the ice, to  the indigenous human societies that have developed in close connection with their  environment, these communities are uniquely adapted to what many outside the  region would view as a very severe climate.   

Life in the Arctic has historically been both vulnerable and resilient. Factors that  contribute to the Arctic’s vulnerability include its relatively short growing season  and smaller variety of living things compared to temperate regions. In addition,  arctic climate is highly variable, and a sudden summer storm or freeze can wipe out  an entire generation of young birds, thousands of seal pups, or hundreds of caribou  calves. Yet some arctic species have also displayed remarkable resilience to historic  extremes, as evidenced by the recovery of populations that have occasionally been  decimated by climatic variations.

The increasingly rapid rate of recent climate change poses new challenges to the resilience of arctic life. In addition to the impacts of climate change, many other stresses brought about by human activities are simultaneously affecting life in the Arctic, including air and water contamination, overfishing, increasing levels of ultraviolet radiation due to ozone depletion, habitat alteration and pollution due to resource extraction, and increasing pressure on land and resources related to the growing human population in the region. The sum of these factors threatens to overwhelm the adaptive capacity of some arctic populations and ecosystems.