WWF Arctic Programme httpwwwngo gridanowwfap

WWF's Arctic Programme began in 1992. In addition to conservation work, WWF staff also work interna tionally to highlight the impacts of climate change. The international climate change campaign is designed to raise public concern about the need to reduce greenhouse gas emissions, encourage policymakers to introduce effective measures, and form innovative partnerships with progressive businesses. The Campaign has published a series of studies on the impacts of climate change on coral reefs, life in the oceans, the Arctic, the world's forests, national parks, popular tourist locations, bird migration, and public health.

Aynslie Ogden

See also Arctic Council; Arctic Research Consortium of the United States (ARCUS); Climate: Research Programs; Health: Environmental Initiatives; Intergovernmental Panel on Climate Change (IPCC); Northern Climate ExChange; World Wide Fund for Nature (WWF) International Arctic Programme

Further Reading

ACIA, Implementation Plan, Arctic Climate Impact Assessment—An Assessment of Consequences of Climate Variability and Change and the Effects of Increased UV in the Arctic Region, 2000 AMAP, Arctic Pollution Issues: A State of the Arctic Environment Report, Oslo: Arctic Monitoring and Assessment Program, 1997 AMAP, AMAP Assessment Report: Arctic Pollution Issues,

Oslo: Arctic Monitoring and Assessment Program, 1998 Arctic Council, Declaration on the Establishment of the Arctic

Council, Ottawa, Canada, 1996 ARCUS, Arctic Information and Data: A Guide to Selected Resources (2nd edition), Fairbanks, Alaska: US Polar Information Working Group, 1996 Ashford, Graham & Jennifer Castledon, Inuit Observations on Climate Change Final Report, Winnipeg, Manitoba: International Institute for Sustainable Development, 2001 Christensen, Tove (editor), Arctic Bulletin, Oslo, Norway: World Wildlife Fund International Arctic Programme, see http://www.ngo.grida.no/wwfap/core/publications/arctic_ bulletin.html

CICERO, Annual Report 2000, Oslo, Norway: CICERO, 2000 Eliott, Susannah, Global Change Newsletter, International

Geosphere-Biosphere Program, Sweden Global Climate Coalition, Climate action agenda for the 21st century, available on-line at http://www.globalclimate.org/ Policy_00_0301.htm Houghton, J.T., Y. Ding, D.J. Griggs, M. Noguer, P.J. van der Linden & D. Xiaosu (editors), Climate Change 2001: The Scientific Basis, Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), Cambridge and New York: Cambridge University Press, 2001 ICLEI, ICLEI 10th Anniversary Biennial Report 1998-99, 1999 Jacobson, Harold K. & Martin F. Price, "A framework for research on the human dimensions of global environmental change." IHDP Report Series No. 1, 1990

McCarthy, James, Osvaldo F. Canziani, Neil A. Leary, David J. Dokken & Kasey S. White (editors), Climate Change 2001: Impacts, Adaptation and Vulnerability, Contribution of Working Group II to the Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), Cambridge and New York: Cambridge University Press, 2001

Metz, Bert, Ogunlade Davidson, Rob Swart & Jiahua Pan (editors), Climate Change 2001: Mitigation, Contribution of Working Group III to the Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), Cambridge and New York: Cambridge University Press, 2001

NOAA Magazine, Publication of the National Oceanic and Atmospheric Administration (NOAA), NOAA Public Affairs, Washington, District of Columbia Ogden, Aynslie, Northern Climate ExChange Annual Report 2000-2001, Whitehorse, Yukon: Northern Climate ExChange, 2001 Rogne, Odd (editor), IASC-Progress Newsletter, Oslo, Norway: International Arctic Science Committee Secretariat, available at http://www.iasc.no/Newsletters/default.htm WCRP, Annual Review of the World Climate Research Programme Report of the Twenty-First Session of the Joint Scientific Committee, Geneva, Switzerland: World Climate Research Program, 2000

CLIMATE OSCILLATIONS

The weather in the Arctic, as in other locations, changes from day to day, month to month, and year to year. The climate, the average weather for a time of year computed over a few years or over many years, can change on many different time scales. For example, it can change from one five-year period to the next or one 30-year period to the next. When the climate moves from one mode to another and back again in slow, irregular patterns, we call the changes a climate oscillation. There are three related oscillations that are currently recognized as being important in the Arctic: the North Atlantic Oscillation (NAO), the Arctic Oscillation (AO), and the Pacific Decadal Oscillation (PDO). Each has a large impact on the regional climate of the Arctic.

The most well known of these is the NAO. The weather in the North Atlantic, Europe, and eastern North America is dominated by two large (>1000 km) weather systems seen in the mean surface air pressure: the Icelandic Low and the Azores High. The Icelandic Low is an average low-pressure area centered near Iceland. It is the result of many storms forming, growing, or passing near the shores of Iceland, each with a low-pressure center. The Azores High is a large high-pressure region, or anticyclone, located farther south, with the center between Bermuda and Africa. The strength of the Iceleandic Low is reflected in the difference in the surface air pressure measured at two stations, commonly taken as Lisbon, Portugal minus Stykkisholmur/Reykjavik Iceland. If the Icelandic

The indices for three climate measures are shown for a 100-year period. The points indicate the winter (December through March) average values and the lines indicate five-year running mean values. The indices are each normalized to have a mean of zero and a standard deviation of one. Sources: NAO index was obtained from Jim Hurrell (http://www.cgd.ucar.edu/~jhurrell/nao.html); AO index from David Thompson (http://www.atmos.colostate.edu/ ao/Data/ao_index.html); PDO index from the University of Washington's Joint Institute for the Study of the Atmosphere and Oceans (JISAO) (http://jisao.washington.edu/pdo)

The indices for three climate measures are shown for a 100-year period. The points indicate the winter (December through March) average values and the lines indicate five-year running mean values. The indices are each normalized to have a mean of zero and a standard deviation of one. Sources: NAO index was obtained from Jim Hurrell (http://www.cgd.ucar.edu/~jhurrell/nao.html); AO index from David Thompson (http://www.atmos.colostate.edu/ ao/Data/ao_index.html); PDO index from the University of Washington's Joint Institute for the Study of the Atmosphere and Oceans (JISAO) (http://jisao.washington.edu/pdo)

Low is strong, the difference is large, and the NAO index is high. When this occurs, more warm, moist air flows into northern Europe from the Atlantic (moving counterclockwise around the Icelandic Low), and Europe experiences relatively warm moist weather. Storms and warmer air intrude farther to the north and east, warming the Barents Sea region and even western Siberia. Eastern Canada and the Labrador Sea, on the other hand, are in a more northerly flow, with cold-er-than-normal weather and more extensive sea ice. The patterns reverse when the Icelandic Low is weak and the NAO index is low.

There is a long historical record for the weather stations in Iceland and Portugal stretching back nearly 150 years, and climatologists have found that the

Climate characteristics associated with three climate oscillations

Positive NAO

Positive AO

Positive PDO

Relatively lower pressure near Iceland.

Warmer and wetter winters in northern Europe and warmer winters in Siberia and Alaska. Less ice in the Barents Sea. Colder winters in Eastern Canada.

More sea ice in Baffin Bay, Labrador Sea, and Hudson Bay. Increase in ice export through Fram Strait.

Relatively lower pressure near the North Pole.

More rapid ice transport across the

Arctic Ocean and more ice export through Fram Strait.

Warmer air temperatures in Europe,

Siberia, and Alaska. Colder temperatures west of Greenland.

More ice in the Bering Sea during the winter.

Warmer waters in the north Pacific near the Alaska and British Columbia coasts. Lower air pressure near the Aleutians.

Larger salmon catches in Alaska and smaller on the US west coast.

winter NAO index, while fluctuating considerably from month to month and year to year, on the average changes slowly from a positive value to a negative value and back again. This oscillation is accompanied by a string of relatively mild winters in Europe and harsh winters in Greenland and Eastern Canada when the index is high, and then a string of harsh winters in northern Europe and mild winters in Greenland and Eastern Canada when the index is low. The regional connections to the NAO index are strongest in the winter months.

Encompassing the NAO is a hemispheric-wide fluctuation, the Arctic Oscillation, also known as an Annular Mode. This fluctuation is associated with the strength of the circulation of the winds that circle the globe in a west to east direction centered at midlati-tudes, 40-60° N, called the polar vortex. The strength of these winds in the winter is also known to change from strong (positive AO index) to weak (negative AO index) and back again. The NAO is often thought of as a regional manifestation of the AO. Commonly, though not always, when the AO index is high, so is the NAO. Positive AO phases are associated with warmer winter temperatures throughout the Arctic, except in eastern Canada and the Labrador Sea. The positive AO index is also associated with low air pressures near the North Pole and greater ice export from the Arctic Ocean through Fram Strait, located along the northeast coast of Greenland. The circulation patterns associated with the AO and the NAO are known to extend well into the stratosphere.

The causes for the changes in the atmospheric circulation reflected in the changes in the indices are not well understood. Evidence suggests they are related to natural modes of variability of the atmosphere, which do not need external causes to occur, but other factors may relate to the strength and timing of the changes in the indices. For example, the sea surface temperature has a strong influence on the atmospheric circulation. Solar activity, volcanoes, sea ice extent, or greenhouse gases may also play a role. The last 30

years have seen the AO and NAO indices in a mostly positive mode.

A third climate oscillation influencing the Arctic is the PDO. The most distinctive patterns in this case are not found, in the air pressure, but in the sea surface temperature (SST). This oscillation is associated with warmer SSTs along the coast of Alaska and British Columbia in its positive warm phase. It is correlated with precipitation and snow pack depth in the Pacific northwest and in Alaska. Important changes in salmon catches are also associated with the PDO, with larger catches obtained in Alaska and lower catches in California, Oregon, and Washington during the warm phase. The air pressure patterns are also influenced by the PDO. The warm phase is associated with lower pressures in the north Pacific, in the region of the Aleutian Low, similar to what is found in the Atlantic with the NAO. An index based on air pressures has also been used, called the North Pacific Oscillation, but, so far, the one based on the SSTs has proven more useful in determining regional climate patterns.

Another well-known climate oscillation is the El Niño Southern Oscillation (ENSO) that is located in the equatorial Pacific Ocean. This oscillation occurs in periods of three to seven years and is associated with a strong warming of the waters off Peru. The temperature and precipitation in many tropical and some mid-latitude regions are strongly influenced by ENSO, but, so far, meteorologists have not discovered strong links between Arctic climate and the ENSO. There are, however, some weak correlations found with the air temperature, particularly in Arctic North America.

The existence of these slow climate changes, in which the climate moves from one mode to another and back again, greatly complicates the analysis of climate change in the Arctic, a change that may be the result of the buildup of anthropogenic (from human activity) greenhouse gases. Much of the warming observed in the Arctic in the last half century can be attributed to changes in the AO. The AO is currently in a mostly positive mode. Will it shift back to a negative mode as in the past, and bring with it cooling of the high Arctic? Or is the change to a mostly positive mode part of a long-term global climate shift brought on by increased levels of greenhouse gases? These are important questions that climatologists around the world are currently actively pursuing.

R.W. Lindsay

See also Climate; Climate Change

Further Reading

Arctic Oscillation website: horizon.atmos.colostate.edu/ao/

index.html (David W.J. Thompson) Hodges, Glenn, "The new cold war. Stalking arctic climate change by submarine." National Geographic, March (2000) 30-41

Hurrell, J.W., "Decadal trends in the North Atlantic Oscillation: regional temperatures and precipitation." Science, 269 (1995): 676-679 Hurrell, J.W., Y. Kushnir & M. Visbeck, "The North Atlantic

Oscillation." Science, 291 (5504) (2001): 603-605 Kerr, R.A., "A new force in high-latitude climate." Science,

284(5412) (1999): 241-242 Mantua, N.J., S.R. Hare, Y. Zhang, J.M. Wallace & R.C. Francis, "A Pacific interdecadal climate oscillation with impacts on salmon production." Bulletin of the American Meteorological Society, 78 (1997): 1069-1079 North Atlantic Oscillation website: www.cgd.ucar.edu/~jhur-

rell/nao.html (Jim Hurrell) Pacific Decadal Oscillation website: tao.atmos.washington.edu/ pdo/

Thompson, D.W.J. & J.M. Wallace, "The Arctic Oscillation signature in the wintertime geopotential height and temperature fields." Geophysical Research Letters, 25(9) (1998): 1297-1300

Thompson, D.W.J., S. Lee & M.P. Baldwin, "Atmospheric Processes Governing the Northern Hemisphere Annular Mode/North Atlantic Oscillation." In The North Atlantic Oscillation: Climate Significance and Environmental Impact, edited by J.W. Hurrell, Y. Kushnir, G. Ottersen & M. Visbeck, Washington, D.C: American Geophysical Union, 2003 Wallace, J.M. & D.S. Gutzler, "Teleconnections in the geopo-tential height field during the northern hemisphere winter." Monthly Weather Review, 109 (1981): 784-812 Wallace, J.M. & D.W.J. Thompson, "Annular modes and climate prediction." Physics Today, February (2002) 28-33

CLIMATE: RESEARCH PROGRAMS

Climatological information was crucial to early air and sea route development in the Arctic, and early research on a national scale focussed on establishing a network of meteorological and drifting stations to aid navigation. Global climate modeling beginning in the 1970s recognized the importance of polar land and sea ice in climatic feedback processes, and international climate programs were initiated. Ice core records from polar ice have been particularly valuable in providing a long record of natural climate variability. Research programs addressing Arctic climate have since the 1980s focussed on anthropogenic climate change. With the Arctic predicted to warm earlier and to a greater degree than the global mean, circum-Arctic countries and organizations have interest in more detailed regional models.

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