The Arctic is extremely vulnerable to observed and projected climate change and its impacts. The Arctic is now experiencing some of the most rapid and severe climate change on earth. Over the next 100 years, climate change is expected to accelerate, contributing to major physical, ecological, social, and economic changes, many of which have already begun. Changes in arctic climate will also affect the rest of the world through increased global warming and rising sea levels.
1. Arctic climate is now warming rapidly and much larger changes are projected.
• Annual average arctic temperature has increased at almost twice the rate as that of the rest of the world over the past few decades, with some variations across the region.
• Additional evidence of arctic warming comes from widespread melting of glaciers and sea ice, and a shortening of the snow season.
• Increasing global concentrations of carbon dioxide and other greenhouse gases due to human activities, primarily fossil fuel burning, are projected to contribute to additional arctic warming of about 4-7°C over the next 100 years.
• Increasing precipitation, shorter and warmer winters, and substantial decreases in snow cover and ice cover are among the projected changes that are very likely to persist for centuries.
• Unexpected and even larger shifts and fluctuations in climate are also possible.
2. Arctic warming and its consequences have worldwide implications.
• Melting of highly reflective arctic snow and ice reveals darker land and ocean surfaces, increasing absorption of the sun’s heat and further warming the planet.
• Increases in glacial melt and river runoff add more freshwater to the ocean, raising global sea level and possibly slowing the ocean circulation that brings heat from the tropics to the poles, affecting global and regional climate.
• Warming is very likely to alter the release and uptake of greenhouse gases from soils, vegetation, and coastal oceans.
• Impacts of arctic climate change will have implications for biodiversity around the world because migratory species depend on breeding and feeding grounds in the Arctic.
3. Arctic vegetation zones are very likely to shift, causing wide-ranging impacts.
• Treeline is expected to move northward and to higher elevations, with forests replacing a significant fraction of existing tundra, and tundra vegetation moving into polar deserts.
• More-productive vegetation is likely to increase carbon uptake, although reduced reflectivity of the land surface is likely to outweigh this, causing further warming.
• Disturbances such as insect outbreaks and forest fires are very likely to increase in frequency, severity, and duration, facilitating invasions by non-native species.
• Where suitable soils are present, agriculture will have the potential to expand northward due to a longer and warmer growing season.
4. Animal species' diversity, ranges, and distribution will change.
• Reductions in sea ice will drastically shrink marine habitat for polar bears, ice-inhabiting seals, and some seabirds, pushing some species toward extinction.
• Caribou/reindeer and other land animals are likely to be increasingly stressed as climate change alters their access to food sources, breeding grounds, and historic migration routes.
• Species ranges are projected to shift northward on both land and sea, bringing new species into the Arctic while severely limiting some species currently present.
• As new species move in, animal diseases that can be transmitted to humans, such as West Nile virus, are likely to pose increasing health risks.
• Some arctic marine fisheries, which are of global importance as well as providing major contributions to the region’s economy, are likely to become more productive. Northern freshwater fisheries that are mainstays of local diets are likely to suffer.
5. Many coastal communities and facilities face increasing exposure to storms.
• Severe coastal erosion will be a growing problem as rising sea level and a reduction in sea ice allow higher waves and storm surges to reach the shore.
• Along some arctic coastlines, thawing permafrost weakens coastal lands, adding to their vulnerability.
• The risk of flooding in coastal wetlands is projected to increase, with impacts on society and natural ecosystems.
• In some cases, communities and industrial facilities in coastal zones are already threatened or being forced to relocate, while others face increasing risks and costs.
6. Reduced sea ice is very likely to increase marine transport and access to resources.
• The continuing reduction of sea ice is very likely to lengthen the navigation season and increase marine access to the Arctic’s natural resources.
• Seasonal opening of the Northern Sea Route is likely to make trans-arctic shipping during summer feasible within several decades. Increasing ice movement in some channels of the Northwest Passage could initially make shipping more difficult.
• Reduced sea ice is likely to allow increased offshore extraction of oil and gas, although increasing ice movement could hinder some operations.
• Sovereignty, security, and safety issues, as well as social, cultural, and environmental concerns are likely to arise as marine access increases.
7. Thawing ground will disrupt transportation, buildings, and other infrastructure.
• Transportation and industry on land, including oil and gas extraction and forestry, will increasingly be disrupted by the shortening of the periods during which ice roads and tundra are frozen sufficiently to permit travel.
• As frozen ground thaws, many existing buildings, roads, pipelines, airports, and industrial facilities are likely to be destabilized, requiring substantial rebuilding, maintenance, and investment.
• Future development will require new design elements to account for ongoing warming that will add to construction and maintenance costs.
• Permafrost degradation will also impact natural ecosystems through collapsing of the ground surface, draining of lakes, wetland development, and toppling of trees in susceptible areas.
8. Indigenous communities are facing major economic and cultural impacts.
• Many Indigenous Peoples depend on hunting polar bear, walrus, seals, and caribou, herding reindeer, fishing, and gathering, not only for food and to support the local economy, but also as the basis for cultural and social identity.
• Changes in species’ ranges and availability, access to these species, a perceived reduction in weather predictability, and travel safety in changing ice and weather conditions present serious challenges to human health and food security, and possibly even the survival of some cultures.
• Indigenous knowledge and observations provide an important source of information about climate change. This knowledge, consistent with complementary information from scientific research, indicates that substantial changes have already occurred.
9. Elevated ultraviolet radiation levels will affect people, plants, and animals.
• The stratospheric ozone layer over the Arctic is not expected to improve significantly for at least a few decades, largely due to the effect of greenhouse gases on stratospheric temperatures. Ultraviolet radiation (UV) in the Arctic is thus projected to remain elevated in the coming decades.
• As a result, the current generation of arctic young people is likely to receive a lifetime dose of UV that is about 30% higher than any prior generation. Increased UV is known to cause skin cancer, cataracts, and immune system disorders in humans.
• Elevated UV can disrupt photosynthesis in plants and have detrimental effects on the early life stages of fish and amphibians.
• Risks to some arctic ecosystems are likely as the largest increases in UV occur in spring, when sensitive species are most vulnerable, and warming-related declines in snow and ice cover increase exposure for living things normally protected by such cover.
10. Multiple influences interact to cause impacts to people and ecosystems.
• Changes in climate are occurring in the context of many other stresses including chemical pollution, overfishing, land use changes, habitat fragmentation, human population increases, and cultural and economic changes.
• These multiple stresses can combine to amplify impacts on human and ecosystem health and well-being. In many cases, the total impact is greater than the sum of its parts, such as the combined impacts of contaminants, excess ultraviolet radiation, and climatic warming.
• Unique circumstances in arctic sub-regions determine which are the most important stresses and how they interact.