Natural Systems

Changes in air temperature, precipitation patterns, and sea ice extent combine to drive changes in ecological systems in the Arctic. These changes may result in increased warming, along with other impacts.

Ecological change

Changes in the surface energy budget lead to changes in soil frozen state and vegetation. Along with rising temperatures, seasonal sea ice loss is considered a major driver of ecological change in the Arctic. Vegetation data are showing increased greenness, indicating more plant growth (increased productivity). In certain areas shrubs and trees are becoming more abundant, or are thriving in areas further north of their historical range. Increased shrub and tree cover can contribute to warming by decreasing the albedo (the ability to reflect energy) of the Earth surface. A 2013 paper by Chapin et al. provides an overview of some of the ecological changes that are being observed.

illustration of ecological systemThe sea-ice biome influences the abundance, distribution, seasonality, and interactions of marine and terrestrial species by its presence (A). It is unique for its complete seasonal disappearance in portions of its distribution. Lengthening of this annual period of absence and an overall decline in ice extent, thickness, and stability will have considerable consequences for these species and interactions (B). Courtesy Post et al., Science.

References

Chapin, F. S. III, J. T. Randerson, A. D.McGuire, J. A. Foley, and C. B. Field. 2013. Changing feedbacks in the climate-biosphere system. Front. Ecol. Environ. 6, 313–320, doi:10.1890/080005.

Post, Eric, Uma S. Bhatt, Cecilia M. Bitz, Jedediah F. Brodie, Tara L. Fulton, Mark Hebblewhite, Jeffrey Kerby, Susan J. Kutz, Ian Stirling, and Donald A. Walker. 2013. Ecological consequences of sea-ice decline. Science 2 August 2013: vol. 341, no. 6145, pp. 519-524, doi: 10.1126/science.1235225.

Bhatt, U.S., D.A. Walker, M.K. Raynolds, J.C. Comiso, H.E. Epstein, G. Jia, R. Gens, J.E. Pinzon, C.J. Tucker, C.E. Tweedie, and P.J. Webber.  2010.  Circumpolar Arctic tundra vegetation change is linked to sea ice decline.  Earth Interactions, 14.

Changes in frozen ground

Ground that has been frozen for many thousands of years is warming and thawing. Thermokarst lakes once supported by permanently frozen ground are drying, and the water cycles of many areas are altered. The Arctic is greening: plants are becoming more abundant and productive, and shrubs and trees are advancing north in warmer conditions, replacing tundra vegetation. Some animal species are losing habitat, and food chains are disrupted. Some Arctic residents and industry are losing buildings, roads, and other infrastructure as ground that was once permanently frozen thaws.

In some parts of the Arctic, the loss of sea ice exposes thawed shorelines to the full force of wind and waves during fierce Arctic storms, resulting in rapid erosion. The warmer ocean waters also thaw the permafrost that holds together sediments in coastal bluffs. In this photograph of a collapsed shoreline along Alaska's Bering Sea coast, ice-rich permafrost can be seen. As once-permanently frozen ground thaws, it becomes even more susceptible to coastal erosion. Some coastlines in this region retreated more than 24 meters (80 feet) in 2007. (Photograph courtesy Benjamin Jones, USGS)

Reference

Jones, B.M., Arp, C.D., Jorgenson, M.T., Hinkel, K.M., Schmutz, J.A., and Flint, P.L. 2009. Increase in the rate and uniformity of coastline erosion in arctic Alaska. Geophysical Research Letters Volume 36, Issue 3, February 2009, DOI: 10.1029/2008GL036205.

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