Permafrost

118
Permafrost, Climate Change and the Coupled Climate System
Andrew G. Slater 1 and David M. Lawrence 2
(1. NSIDC/CIRES, University of Colorado, Boulder, CO, USA
2. National Center for Atmospheric Research, Boulder, CO, USA)
Abstract: Observations of changes in the state of permafrost in recent times are many and
varied. Appearance and disappearance of lakes, degradation of ice wedges and changes in river
channel morphology are several of the processes that have been linked to thawing of permafrost
and warming of soil temperatures. Thus there is a need for assessing the effect of climate
change frozen ground and permafrost. For example, knowledge of the state of the ground is
important for assessing likely impacts to human infrastructure such as pipelines or railroads.
Further, altering the state of the below ground system can have a large influence upon ecology,
hydrology and trace gas emissions from high latitude regions.
In this research, we examine the advantages and disadvantages of analyzing permafrost
under climate change within a fully coupled system. Some of the advantages that coupled
system models have to offer include the ability to account for interactive hydrology and its
associated feedbacks to the atmosphere. For example, a coupled model will capture the
influence of additional snow cover and its associated infiltration patterns upon the thermal
regime of the ground, which in turn can affect circulation patterns in later seasons. Conversely,
a potential disadvantage of direct assessment of the state of permafrost from a climate model is
that the land surface model component of coupled climate system models may not be as
sophisticated as dedicated permafrost models with respect to resolving the thermal regime of
freeze-thaw processes. While land surface models have recently been increasing in complexity,
they may still be deficient in some areas.
Using a hierarchy of models, ranging from temperature index models, through to analytic
steady-state models, soil diffusion models and full energy balance land surface models we
explore both the strengths and weaknesses of particular strategies for diagnosing changes in
permafrost as well as determining the interdependent relationship between climate change and
permafrost. Some of these matters will be explored within a coupled land-atmosphere general
circulation model (CCSM3).
Key words: Permafrost, climate change, modeling
Comparison of Tibetan Plateau Rainfall to Permafrost Distribution
Anita D. Rapp 1 and Lijuan Ma 2
(1.Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado, USA;
2.Chinese Academy of Meteorological Sciences, China Meteorological Administration, Beijing, China)
Abstract: Permafrost plays an essential role in high-latitude and high-altitude environments.
Many environmental parameters have been shown to contribute to the formation and
degradation of permafrost, such as air temperature, snow depth, vegetation canopy, soil
moisture and texture, organic matter accumulation, hydrologic movement, as well as