Alaska Science Outreach

About    Contact    Home   


Catch & Release


International Assessment Enumerates Climate Change Impacts Across the Arctic

This article by Robert W. Corell, Pål Prestrud, and Gunter Weller was featured in the Winter 2004/2005 issue of Witness the Arctic, posted on the ARCUS Web site. A direct link to download the entire newsletter in PDF format is available at the end of this article.

For the past four years, almost 300 scientists and experts, including elders and other insightful residents, have worked on a comprehensive analysis, synthesis, and documentation of the impacts and consequences across the Arctic of climate variability and changes, including the impacts induced by increases in ultraviolet (UV) radiation. The Arctic Council inaugurated the project in 2000, charging the Arctic Climate Impact Assessment (ACIA) to

  • evaluate and synthesize knowledge of how climate and UV radiation have been changing in the Arctic, how they are projected to change in the future, and the likely impacts of those changes on environmental, human health, social, cultural, and economic systems; and

  • provide useful information and recommendations to the governments, organizations, and peoples of the Arctic and the world to help them respond to the challenges and opportunities presented by climate change.

The Arctic Council tasked two of its working groups, the Arctic Monitoring and Assessment Programme (AMAP) and Conservation of Arctic Flora and Fauna (CAFF), to conduct the ACIA in association with the International Arctic Science Committee (IASC). All eight of the arctic nations and the U.K. provided financial and in-kind support.

An Assessment Steering Committee (ASC), established by AMAP, CAFF, and IASC, provided overall coordination for the ACIA and liaison with relevant national and international organizations, including indigenous peoples’ groups and the Intergovernmental Panel on Climate Change (IPCC). The ASC guided the development of the assessment through teams of authors, drawn from many disciplines and countries, who participated in a series of focused workshops. The assessment produced two reports:

  • a scientific report, totaling over 1000 pages in 18 chapters, which was subject to a comprehensive external review by an independent group of more than 225 international scientists and other experts; and

  • a 140-page overview report, designed for a broad non-scientific readership and also externally reviewed.

The ACIA reports will be used in the development of the IPCC Fourth Assessment Report, to be completed in 2007.

The ACIA teams of authors submitted the scientific and overview reports to the Arctic Council during its ministerial meeting in Reykjavik, Iceland, in November 2004. Just prior to the ministerial meeting, the ACIA hosted an International Scientific Symposium in Reykjavik to examine issues connected to climate change in the circumpolar Arctic and its environmental and societal consequences, including indigenous peoples’ perspectives and observations. More than 250 participants presented 150 papers and discussed the ACIA results and their background in an integrated circumpolar context and in light of global, regional, and sub-regional environmental management and policy development. Participants also identified knowledge gaps and priorities for new research and monitoring and outlined significant national, bilateral, and multilateral activities that have contributed to ACIA.

At the ministerial meeting, the Arctic Council released a seven-page policy document responding to the ACIA findings and providing general recommendations for mitigation and adaptation measures.

Major Findings

The ACIA details and projects significant disruptive impacts from climate change and UV radiation in the Arctic, while identifying a number of potential opportunities for indigenous and other residents, communities, economic sectors, and governments of the region. To develop its projections, the assessment used a single scenario of the future, the IPCC Special Report on Emissions Scenarios (SRES) B2 scenario. B2 is a “moderate” climate change scenario, which projects global carbon dioxide emissions more than doubling by 2100 from about six gigatons of carbon (GtC) in 1990 to about 14 GtC; under this scenario, nine Global Climate Models (GCMs) predict an average global temperature response of +2.2°C (range +0.9—+3.4°C) for the period 2071-2100 compared to 1961-1990. To provide model output specific to the ACIA, the B2 scenario was implemented on five selected GCMs. With some variation, these GCMs predict about twice as much warming in the Arctic compared to the global average over a similar time period; this result accords with other IPCC projections.

Evidence of recent warming in the Arctic includes records of increasing temperatures, melting glaciers, reductions in extent and thickness of sea ice, thawing permafrost, and rising sea level. There are regional variations and patterns within this overall trend; for example, in most places, temperatures in winter are rising more rapidly than in summer. In Alaska and western Canada, average winter temperatures have increased by as much as 3-4°C over the past 60 years, while the global average increase over the past 100 years has been only about 0.6 ± 0.2°C.

Ozone depletion in northern latitudes and the resultant changes in UV radiation have increased markedly during the past decade, with some sectors of the Arctic experiencing short-term reductions in ozone of about 20% and increases of more than 40% in incident UV radiation.

Over the past 30 years, arctic sea ice extent has decreased on average by about 10%, and this change has been 20% faster over the past two decades than over the past three decades. Arctic sea ice extent and seasonal duration are projected to decrease even more rapidly in the future, leading to seasonal opening of potentially important marine transportation routes and significant changes in albedo, cloudiness, humidity, exchanges of heat and moisture, and ocean circulation, particularly along coastlines and near ice margins. The average of the five ACIA model simulations project substantial and accelerating reductions in summertime sea ice around the entire Arctic Basin, with one model projecting an ice-free Arctic in the summer by the middle of this century. The average of the five ACIA models projects that the navigation season in the Northern Sea Route along the Eurasian coast from the Atlantic to the Bering Strait, currently 20-30 days per year, will increase to 90-100 days (150 days for ice-breaking vessels) by 2080, with one model indicating it is likely to open to this degree by mid-century. This could have important economic and political implications, increasing access to the region’s resources and raising issues of sovereignty, safety, and environmental preservation.

In addition, access to sea ice is critical to the survival and reproduction of many high latitude marine mammals. Scientists and arctic residents are concerned that the thinning and depletion of sea ice in the Arctic will cause the extinction of key marine mammals, including polar bear, walrus, and some species of seal. Loss of these species threatens the hunting culture of Inuit in Alaska, northern Canada, Greenland, and Chukotka, Russia.

The total land-based ice in the Arctic is estimated at 3,100,000 km³, which corresponds to a sea-level equivalent of about 8 m. Recent studies of glaciers in Alaska already indicate an accelerated rate of melting, representing about half of the estimated loss of mass by glaciers worldwide. Over the past two decades, the melt area on the Greenland Ice Sheet has increased on average by about 0.7% per year (or about 16% from 1979-2002), with considerable interannual variation. IPCC estimated that a sustained increase in arctic temperatures of 3°C would lead to the melting of the Greenland Ice Sheet over a period of 1000 years—the ACIA models suggest that regional warming will be much higher than 3°C by the end of the 21st century.

Rising temperatures lead to taller, denser vegetation, promoting the expansion of forests into arctic tundra, and tundra into polar deserts. This change, along with rising sea levels, is projected to shrink tundra area to its lowest extent in at least the past 21,000 years, potentially reducing the breeding area for many migratory bird species and the grazing areas for animals that depend on tundra and polar desert habitats. Half the current tundra area is projected to disappear in this century. While arctic agriculture is a small industry in global terms, the region’s potential for commercial crop production is projected to advance northward.

Inland peoples throughout the Arctic depend on caribou and reindeer herds, which need abundant tundra vegetation and good foraging conditions, especially during the calving season. In addition to reducing the area of tundra suitable for grazing, climate-induced changes are projected to increase incidence of freeze-thaw cycles and freezing rain, both of which prevent animals from eating iced-over vegetation. Further, migrations of other species (moose, red deer, etc.) into traditional pasturelands are likely to disturb some populations. Although much of the redistribution of species is climate induced, the development of roadways, pipelines, and other infrastructure also contribute.

Marine fisheries are a vital part of the economy of virtually every arctic country and provide an important food source globally. Because they are largely controlled by factors such as local weather conditions, ecosystem dynamics, and management decisions, projecting the impacts of climate change on marine fish stocks is difficult. Based on available information, however, projected warming is likely to improve conditions for some important arctic fish stocks such as cod and herring, while negatively affecting others. For example, the extent of northern shrimp will probably contract, reducing the large catch (about 100,000 tons a year) currently taken from Greenlandic waters. While the total effect of climate change on fisheries will likely be less important than decisions regarding management, specific communities that are heavily dependent on fisheries may be dramatically affected.

Permafrost presently underlies most of the land surfaces in the Arctic, and thawing ground will disrupt transportation, buildings, and other infrastructure. Permafrost temperatures over most of the sub-arctic land areas have increased by up to 2°C over the past few decades, and the depth of the layer that thaws each year is increasing in many areas. Over the next century, permafrost degradation is projected over 10-20% of the present permafrost area, and the southern limit of permafrost is projected to shift northward by several hundred kilometers. Rising temperatures are already degrading land routes over frozen tundra and across ice roads and bridges, and the incidence of mud and rockslides and avalanches is likely to increase. The number of days per year in which heavy equipment travel on the tundra can be approved by the Alaska Department of Natural Resources has dropped about 50% in the past 30 years, limiting oil and gas exploration and extraction.

Across the Arctic, indigenous peoples accustomed to the wide range of natural climate variations report changes that are unique in the long experience of their peoples. Residents of the Arctic are likely to face major impacts due to climate and other environmental changes, which are occurring in the context of other interrelated changes. Environmental changes include chemical pollution, habitat destruction, and over-fishing. Social and economic changes include technological innovations, trade liberalization, urbanization, self-determination movements, and increasing tourism.

The impacts will vary with regional differences in climate change and will depend largely on the interactions among the various changes; people’s resilience or vulnerability to climate change depends on the cumulative stresses to which they are subjected as well as their capacity to adapt to these changes. Individual and collective adaptive capacity is affected by political, legal, economic, social, and other factors, including age, lifestyle, gender, and access to resources. Rural arctic residents in small, isolated communities with a fragile system of support, little infrastructure, and marginal or nonexistent public health systems appear to be most vulnerable. People who depend on subsistence hunting and fishing, especially those who rely on just a few species, will be vulnerable to changes that heavily impact those species. Responses to environmental changes are multidimensional and include adjustments in hunting, herding, and fishing practices as well as alterations in the political, cultural, and spiritual aspects of life. Adaptation can involve changes in knowledge and how it is applied—for example, using new weather prediction techniques. Arctic people have historically altered their activities in response to changing conditions; they increasingly indicate, however, that the rapid rate of climate changes is limiting their capacities to adapt.

As the first comprehensive examination of climate change and its impacts in the arctic region, the ACIA represents the initiation of a process, rather than simply a set of reports. The ACIA brought together hundreds of scientists from around the world whose research focuses on the Arctic and incorporated the insights of indigenous peoples who have a long history of gathering knowledge in this region. Linking these different perspectives is an exciting process for both the science community and the residents of the Arctic, and it clearly has great potential to continue to improve understanding of climate change and its impacts.

An analysis of the knowledge gaps revealed by the ACIA suggests that three major topics should be priorities to improve future analyses:

  • sub-regional impacts: assessments of climate change impacts focused on smaller regions have the greatest relevance and utility for residents;
  • socioeconomic impacts: in most cases, only qualitative information on economic impacts is available; and
  • assessing vulnerabilities: assessing vulnerability involves knowledge not just of the consequences of stresses and their interactions, but also of the capacity of the system to adapt.

The Arctic Council asked that ACIA continue its activities over the next decade. The ACIA executive committee will develop a proposed scope, strategy, and implementation plan for future efforts by spring 2005.

The ACIA overview report and policy document are available as PDF downloads from the AMAP web site:; the overview report can also be ordered from Cambridge University Press: The scientific report will be available in early 2005.

For more information, see the ACIA web site:, or contact Robert Corell, ASC Chair (, Pål Prestrud, ASC Vice Chair (, or Gunter Weller, Executive Director of the ACIA Secretariat (

The Winter 2004/2005 issue of Witness the Arctic is available online at:

Witness the Arctic is a newsletter produced biannually by ARCUS providing information on arctic research efforts and initiatives, national policy, international activities, and more.

Mission Statement & Site Policies | About AlaskaWriter LLC | Request Outreach | Request Reprints | Contribute a Story

Copyright 2004 AlaskaWriter LLC