Lab researchers examine the impact of a thawing permafrost on Arctic landscapes

July 27, 2010—Observations indicate that over the past several decades, surface processes in the Arctic have been changing or intensifying. These processes include erosion, expansion of water channel networks, landslides, and degradation of frozen ground previously stable for thousands of years. These changes result from a system-wide response to regional warming and thawing of permafrost, which is ground that has existed at temperatures below freezing for at least two years.

In the article, "Arctic Landscapes in Transition: Responses to Thawing Permafrost," LANL authors and collaborators examine some of the potential factors and impacts of a thawing permafrost. Although some level of landscape change is expected in response to natural climate variability, the scale and rapidity of recently observed changes suggest that Arctic landscapes may be more sensitive to climate change than temperate regions, and therefore capable of rapid responses to temperature perturbations.

As an example of potential changes, the authors examined how the Arctic drainage networks would respond to thawing permafrost and melting ground ice. Permafrost, including ground ice, controls the distribution and routing of water across Arctic landscapes and the stability of frozen soils. These effects induce strong feedbacks on vegetation distributions. The permafrost varies in extent and is extremely heterogeneous, not readily detected remotely, and difficult to model.

The authors conclude that a dynamic Arctic landscape has the potential to alter human and natural systems across a broad range of scales and processes. For example, thawing and release of large carbon reservoirs currently stored in permafrost may influence global climate. Therefore, scientists must develop the capability for a landscape-scale understanding of Arctic responses to climate change in order to assess changes to and vulnerabilities of Arctic ecosystems, carbon, water and energy budgets, infrastructure, and societies. This requires identification of the drivers for change, the responses to these drivers, and the feedbacks between drivers and responses. Remote sensing technologies are needed to detect near-surface and subsurface changes in the Arctic.

The article summarizes research needs to understand and predict Arctic landscape evolution and its impact on hydrology, geomorphology, and carbon cycles. These ideas were developed in a workshop at the University of Alaska Fairbanks. Cathy Wilson of Earth Systems Observations (EES-14), Gary Geernaert of the Institute of Geophysics and Planetary Physics, (INST-OFF), and Larry Hinzman, director of the International Arctic Research Center at the University of Alaska Fairbanks, co-organized and led the workshop. The article appeared in EOS, a publication of the American Geophysical Union. LANL coauthors include J.C. Rowland, G. Altmann, and C.J. Wilson of EES-14; G. L. Geernaert of INST-OFF; A. Mancino of International Research, Analysis, and Development, (IAT-1); B. J. Travis of Computational Earth Sciences (EES-16); and collaborators from the University of Alaska, the National Center for Atmospheric Research, National Hydrology Research Centre (Canada), and Boise State University. The Institute of Geophysics and Planetary Physics funded the LANL work, which supports the Lab's Energy Security mission area.

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Conceptual depiction of the Arctic landscape highlighting observed changes in response to thermal alterations of permafrost and melting of ground ice. Aqua-colored arrows depict water fluxes, and tan arrows denote sediment fluxes. Dissolved and solid constituents such as carbon, nutrients, and trace elements will also follow similar pathways. Arrow size does not reflect relative magnitudes. Observations and modeling suggest that the rate and frequency of the processes depicted will increase with rising Arctic temperatures. Thermokarst topography has depressed areas and hummocks formed by melting permafrost. Active layer refers to seasonal thawed ground, and talik is permanently thawed ground.