In recent years a large, international team of researchers have collaborated closely on the so-called “Arctic Climate Impact Assessment” (ACIA). The purpose of ACIA is primarily to gather and evaluate information on variations and changes in the Arctic climate and their consequences and to procure useful and reliable information to governments, organisations and populations in the Arctic in support of political decisions.

The researchers have evaluated the consequences of climate changes for the environment and the health of Arctic populations and their social and economic impacts on the Arctic communities. Moreover, the researchers have given recommendations as to how the effects of climate changes should be incorporated in more far-reaching decisions on community development. The results of their efforts have been presented in the report “Impact of a Warming Arctic – Arctic Climate Impact Assessment”.

ACIA presents the researchers’ best predictions of the future climate in the Arctic based on current knowledge. Consequences at local scale cannot be predicted, but fairly robust indications are given of what we may expect of the future.

Climate models predict the strongest changes to occur in the Arctic due to the fact that more of the sun’s warm rays will gradually heat the surface of the earth when the areas covered by ice and snow diminish.

The most important changes to occur in the Arctic during the coming ca. 100 years are that

• air temperatures will increase with, on average, 5-7 ^oC
• winter temperatures will increase most significantly, while summer temperatures will increase only negligibly
• winters will become shorter
• the amount of precipitation will increase
• the sea water level will rise between 10 and 90 cm
• the frequency of storm events will increase
• the season with open water will be prolonged
• the ice cover will be considerably reduced
• the inland ice and glaciers will ‘shrink’ due to melting
• the permafrost will disappear in the southern areas
• sea currents may change.

These changes will most probably result in

• larger rivers
• changes in vegetation
• changes in wetland areas
• northwards spreading of plant and animal species
• endangerment of sea birds and sea mammals depending on sea ice
• endangerment of species adapted to the extreme Arctic climate

This may play a decisive role for the Arctic populations. For instance, less sea ice will improve the possibilities of sea transport and increase the access to raw materials; buildings and roads on permafrost will become less stable; stronger and more frequent storms will affect the coasts and town communities along these and thereby change the basis of existence for many Arctic inhabitants. The changes and challenges facing the people will differ locally in the Arctic area.

Background
ACIA was initiated in 2002 by the Arctic Council and the International Arctic Science Committee (IASC). The Arctic Council is an international body of representatives from the eight Arctic countries and from six organizations representing the indigenous people of the Arctic. The council monitors the development in the Arctic area and primarily focuses on the threats and challenges facing the Arctic countries and the Arctic people, among others the expected climatic changes and pollution with environmentally hazardous substances. The International Arctic Science Committee is a scientific organization aimed to further the cooperation on Arctic research across countries and continents.