climate change 1

The resilience and vulnerability of permafrost to climate change depends on complex interactions among topog- raphy, water, soil, vegetation, and snow, which allow permafrost to persist at mean annual air temperatures (MAATs) as high as +2 8C and degrade at MAATs as low as -20 8C. To assess these interactions, we compiled existing data and tested effects of varying conditions on mean annual surface temperatures (MASTs) and 2 m deep temperatures (MADTs) through modeling. Surface water had the largest effect, with water sediment temperatures being ~10 8C above MAAT. A 50% re- duction in snow depth reduces MADT by 2 8C. Elevation changes between 200 and 800 m increases MAAT by up to 2.3 8C and snow depths by ~40%. Aspect caused only a ~1 8C difference in MAST. Covarying vegetation structure, or- ganic matter thickness, soil moisture, and snow depth of terrestrial ecosystems, ranging from barren silt to white spruce (Picea glauca (Moench) Voss) forest to tussock shrub, affect MASTs by ~6 8C and MADTs by ~7 8C. Groundwater at 2- 7 8C greatly affects lateral and internal permafrost thawing. Analyses show that vegetation succession provides strong neg- ative feedbacks that make permafrost resilient to even large increases in air temperatures. Surface water, which is affected by topography and ground ice, provides even stronger negative feedbacks that make permafrost vulnerable to thawing even under cold temperatures.

[1]  Kenji Yoshikawa,et al.  Shrinking thermokarst ponds and groundwater dynamics in discontinuous permafrost near council, Alaska , 2003 .

[2]  F. Chapin,et al.  Plant Community Composition as a Predictor of Regional Soil Carbon Storage in Alaskan Boreal Black Spruce Ecosystems , 2008, Ecosystems.

[3]  Yuri Shur,et al.  Patterns of permafrost formation and degradation in relation to climate and ecosystems , 2007 .

[4]  W. Cline.  Economics of Global Warming, The , 1992 .

[5]  Mikhail Kanevskiy,et al.  Physical and ecological changes associated with warming permafrost and thermokarst in Interior Alaska , 2009 .

[6]  C. Symon,et al.  Arctic climate impact assessment , 2005 .

[7]  J. Houghton,et al.  Climate change 2001 : the scientific basis , 2001 .

[8]  Raymond J. Kopp,et al.  A Proposal for Credible Early Action in US Climate Policy , 2000 .

[9]  Howard E. Epstein,et al.  High stocks of soil organic carbon in the North American Arctic region , 2008 .

[10]  M. Mack,et al.  The role of mosses in ecosystem succession and function in Alaska's boreal forest. , 2010 .

[11]  David G. Victor,et al.  The Collapse of the Kyoto Protocol and the Struggle to Slow Global Warming , 2001 .

[12]  F. Chapin,et al.  Principles of ecosystem stewardship : resilience-based natural resource management in a changing world , 2009 .

[13]  Leslie A. Viereck,et al.  Forest Succession and Soil Development Adjacent to the Chena River in Interior Alaska , 1970, Arctic and Alpine Research.

[14]  T. Jiang.  Economic Instruments of Pollution Control in an Imperfect World , 2003 .

[15]  Vladimir E. Romanovsky,et al.  Evidence for warming and thawing of discontinuous permafrost in Alaska , 1999 .

[16]  R. Tol.  Kyoto, Efficiency, and Cost-Effectiveness: Applications of FUND , 1999 .

[17]  M. Torre Jorgenson,et al.  Permafrost Degradation and Ecological Changes Associated with a WarmingClimate in Central Alaska , 2001 .

[18]  A. McGuire,et al.  The Effect of Moisture Content on the Thermal Conductivity of Moss and Organic Soil Horizons From Black Spruce Ecosystems in Interior Alaska , 2009 .

[19]  V. Romanovsky,et al.  Estimation of soil thermal properties using in-situ temperature measurements in the active layer and permafrost , 2009 .

[20]  R. Striegl,et al.  Increased groundwater to stream discharge from permafrost thawing in the Yukon River basin: Potential impacts on lateral export of carbon and nitrogen , 2007 .

[21]  M. Turetsky,et al.  Effects of wildfire and permafrost on soil organic matter and soil climate in interior Alaska , 2006 .

[22]  F. Chapin,et al.  Methane bubbling from Siberian thaw lakes as a positive feedback to climate warming , 2006, Nature.

[23]  Bo H. Svensson,et al.  Thawing sub‐arctic permafrost: Effects on vegetation and methane emissions , 2004 .

[24]  M. Jorgenson,et al.  Response of boreal ecosystems to varying modes of permafrost degradation , 2005 .

[25]  M. Turetsky,et al.  Interactive Effects of Fire, Soil Climate, and Moss on CO2 Fluxes in Black Spruce Ecosystems of Interior Alaska , 2009, Ecosystems.

[26]  A. Lachenbruch,et al.  Changing Climate: Geothermal Evidence from Permafrost in the Alaskan Arctic , 1986, Science.

[27]  Vladimir E. Romanovsky,et al.  Interannual variations of the thermal regime of the active layer and near‐surface permafrost in northern Alaska , 1995 .

[28]  P. Wilcoxen,et al.  What to expect from an international system of tradable permits for carbon emissions , 1999 .

[29]  O. Davidson,et al.  Climate change 2001 : mitigation , 2001 .

[30]  T. E. Osterkamp,et al.  Characteristics of the recent warming of permafrost in Alaska , 2007 .

[31]  M. Mack,et al.  Plant Species Composition and Productivity following Permafrost Thaw and Thermokarst in Alaskan Tundra , 2007, Ecosystems.

[32]  Kenji Yoshikawa,et al.  Impacts of wildfire on the permafrost in the boreal forests of Interior Alaska , 2002 .

[33]  Peter J. Wilcoxen,et al.  ENERGY PRICES, PRODUCTIVITY, AND ECONOMIC GROWTH , 1993 .

[34]  M. Torre Jorgenson,et al.  Abrupt increase in permafrost degradation in Arctic Alaska , 2006 .

[35]  F. Chapin,et al.  Wetland succession in a permafrost collapse: interactions between fire and thermokarst , 2007 .

[36]  E. S. Melnikov,et al.  Circum-Arctic map of permafrost and ground-ice conditions , 1997 .

[37]  P. Raymond,et al.  A decrease in discharge‐normalized DOC export by the Yukon River during summer through autumn , 2005 .

[38]  Marc Roberts,et al.  Effluent charges and licenses under uncertainty , 1976 .

[39]  Kathleen F. Jones,et al.  Increasing solar heating of the Arctic Ocean and adjacent seas, 1979–2005: Attribution and role in the ice‐albedo feedback , 2007 .

[40]  Peter R. Orszag,et al.  Climate Change: An Agenda for Global Collective Action , 2001 .

[41]  Jesse H. Ausubel,et al.  Climate Impact Assessment , 1985 .

[42]  V. Romanovsky,et al.  Using in-situ temperature measurements to estimate saturated soil thermal properties by solving a sequence of optimization problems , 2007 .

[43]  T. E. Osterkamp,et al.  The effect of permafrost thaw on old carbon release and net carbon exchange from tundra , 2009, Nature.

[44]  S. Trumbore,et al.  Soil Data from a Moderately Well and Somewhat Poorly Drained Fire Chronosequence near Thompson, Manitoba, Canada , 2006 .

[45]  P. Wilcoxen,et al.  Salvaging the Kyoto Climate Change Negotiations , 1997 .

[46]  P. Camill,et al.  Permafrost Thaw Accelerates in Boreal Peatlands During Late-20th Century Climate Warming , 2003 .

[47]  W. Nordhaus.  Reflections on the Economics of Climate Change , 1993 .

[48]  S. Hagemann,et al.  Vulnerability of Permafrost Carbon to Climate Change: Implications for the Global Carbon Cycle , 2008 .

[49]  Vladimir E. Romanovsky,et al.  Effects of unfrozen water on heat and mass transport processes in the active layer and permafrost. , 2000 .

[50]  A. McGuire,et al.  Characteristics of organic soil in black spruce forests: Implications for the application of land surface and ecosystem models in cold regions , 2009 .

[51]  E. S. Melnikov,et al.  Circum-Arctic map of permafrost and ground-ice conditions. Washington, DC: U.S. Geological Survey in Cooperation with the Circum-Pacific Council for Energy and Mineral Resources. Circum-Pacific Map Series CP-45, scale 1:10,000,000, 1 sheet. , 1997 .

[52]  J. Randerson,et al.  The Impact of Boreal Forest Fire on Climate Warming , 2006, Science.

[53]  F. S. Chapin,et al.  The changing effects of Alaska's boreal forests on the climate system , 2010 .

[54]  Rouse Wr,et al.  The role of individual terrain units in the water balance of wetland tundra , 1995 .

[55]  J. Palutikof,et al.  Climate change 2007 : impacts, adaptation and vulnerability , 2001 .

[56]  R. Macdonald,et al.  Sensitivity of the carbon cycle in the Arctic to climate change , 2009 .

[57]  W. Nordhaus.  The 'DICE' Model: Background and Structure of a Dynamic Integrated Climate-Economy Model of the Economics of Global Warming , 1992 .

[58]  C. Burn,et al.  Observations of the "Thermal Offset" in Near-Surface Mean Annual Ground Temperatures at Several Sites near Mayo, Yukon Territory, Canada , 1988 .

[59]  Warwick J. McKibbin,et al.  A Better Way to Slow Global Climate Change , 1997 .

[60]  T. Schelling.  The Cost of Combating Global Warming: Facing the Tradeoffs , 1997 .

[61]  Thomas C. Schelling,et al.  Some economics of global warming , 1992 .

[62]  A. McGuire,et al.  Alaska's Changing Fire Regime - Implications for the Vulnerability of Its Boreal Forests , 2010 .

[63]  Martijn Gough.  Climate change , 2009, Canadian Medical Association Journal.

[64]  W. Nordhaus.  The Cost of Slowing Climate Change: a Survey , 1991 .

[65]  Jon Holmgren,et al.  Snow-Shrub Interactions in Arctic Tundra: A Hypothesis with Climatic Implications , 2001 .

[66]  F. Chapin,et al.  Role of Land-Surface Changes in Arctic Summer Warming , 2005, Science.

[67]  Soedjatmoko,et al.  Managing the global commons , 1982, International Organization.

[68]  Robert J. Evans,et al.  The disappearance of relict permafrost in boreal north America: Effects on peatland carbon storage and fluxes , 2007 .

[69]  M. Woo.  Consequences of Climatic Change for Hydrology in Permafrost Zones , 1990 .