Climatic Change

, Volume 48, Issue 4, pp 551–579

Permafrost Degradation and Ecological Changes Associated with a WarmingClimate in Central Alaska

  • M. Torre Jorgenson
  • Charles H. Racine
  • James C. Walters
  • Thomas E. Osterkamp

DOI: 10.1023/A:1005667424292

Cite this article as:
Jorgenson, M.T., Racine, C.H., Walters, J.C. et al. Climatic Change (2001) 48: 551. doi:10.1023/A:1005667424292


Studies from 1994–1998 on the TananaFlats in central Alaska reveal that permafrostdegradation is widespread and rapid, causing largeshifts in ecosystems from birch forests to fens andbogs. Fine-grained soils under the birch forest areice-rich and thaw settlement typically is 1–2.5 mafter the permafrost thaws. The collapsed areas arerapidly colonized by aquatic herbaceous plants,leading to the development of a thick, floatingorganic mat. Based on field sampling of soils,permafrost and vegetation, and the construction of aGIS database, we estimate that 17% of the study area(263,964 ha) is unfrozen with no previous permafrost,48% has stable permafrost, 31% is partiallydegraded, and 4% has totally degraded. For thatportion that currently has, or recently had,permafrost (83% of area), ∼42% has been affected bythermokarst development. Based on airphoto analysis,birch forests have decreased 35% and fens haveincreased 29% from 1949 to 1995. Overall, the areawith totally degraded permafrost (collapse-scar fensand bogs) has increased from 39 to 47% in 46 y. Based on rates of change from airphoto analysis andradiocarbon dating, we estimate 83% of thedegradation occurred before 1949. Evidence indicatesthis permafrost degradation began in the mid-1700s andis associated with periods of relatively warm climateduring the mid-late 1700s and 1900s. If currentconditions persist, the remaining lowland birchforests will be eliminated by the end of the nextcentury.

Copyright information

© Kluwer Academic Publishers 2001

Authors and Affiliations

  • M. Torre Jorgenson
    • 1
  • Charles H. Racine
    • 2
  • James C. Walters
    • 3
  • Thomas E. Osterkamp
    • 4
  1. 1.ABR, Inc.FairbanksUSAE-mail
  2. 2.U.S. Army Cold Regions Research and Engineering LaboratoryHanoverUSAE-mail
  3. 3.Department of Earth ScienceUniv. Northern IowaCedar FallsUSAE-mail
  4. 4.Geophysical InstituteUniversity of AlaskaFairbanksUSAE-mail