CO2 and CH4 exchanges between land ecosystems and the atmosphere in northern high latitudes over the 21st century

[1] Terrestrial ecosystems of the northern high latitudes (above 50°N) exchange large amounts of CO2 and CH4 with the atmosphere each year. Here we use a process-based model to estimate the budget of CO2 and CH4 of the region for current climate conditions and for future scenarios by considering effects of permafrost dynamics, CO2 fertilization of photosynthesis and fire. We find that currently the region is a net source of carbon to the atmosphere at 276 Tg C yr-1. We project that throughout the 21st century, the region will most likely continue as a net source of carbon and the source will increase by up to 473 Tg C yr−1 by the end of the century compared to the current emissions. However our coupled carbon and climate model simulations show that these emissions will exert relatively small radiative forcing on global climate system compared to large amounts of anthropogenic emissions.

[1]  K. Hirsch,et al.  Direct carbon emissions from Canadian forest fires, 1959-1999 , 2001 .

[2]  Ronald G. Prinn,et al.  Joint Program on the Science and Policy of Global Change Methane Fluxes Between Terrestrial Ecosystems and the Atmosphere at Northern High Latitudes During the Past Century : A Retrospective Analysis with a Process-Based Biogeochemistry Model , 2004 .

[3]  W. R. Cofer,et al.  Estimating fire emissions and disparities in boreal Siberia (1998–2002) , 2004 .

[4]  Yu‐Han Chen,et al.  Estimation of methane and carbon dioxide surface fluxes using a 3-D global atmospheric chemical transport model , 2004 .

[5]  E. Davidson,et al.  Temperature sensitivity of soil carbon decomposition and feedbacks to climate change , 2006, Nature.

[6]  E. Gorham.  Northern Peatlands: Role in the Carbon Cycle and Probable Responses to Climatic Warming. , 1991, Ecological applications : a publication of the Ecological Society of America.

[7]  S. Frolking,et al.  How northern peatlands influence the Earth's radiative budget: Sustained methane emission versus sustained carbon sequestration , 2006 .

[8]  M. Sarofim,et al.  Uncertainty Analysis of Climate Change and Policy Response , 2003 .

[9]  Henry D. Jacoby,et al.  Integrated Global System Model for Climate Policy Assessment: Feedbacks and Sensitivity Studies , 1999 .

[10]  Peter M. Cox,et al.  Climate feedback from wetland methane emissions , 2004 .

[11]  Acia.  Impacts of a Warming Arctic: Arctic Climate Impact Assessment , 2004 .

[12]  R. Protz,et al.  Role of the Hudson Bay lowland as a source of atmospheric methane , 1994 .

[13]  Time-dependent atmospheric CO2 inversions based on interannually varying tracer transport , 2003 .

[14]  E. Kasischke,et al.  Variability in the emission of carbon-based trace gases from wildfire in the Alaskan boreal forest , 2002 .

[15]  Corinna Rebmann,et al.  Productivity of forests in the Eurosiberian boreal region and their potential to act as a carbon sink –‐ a synthesis , 1999 .

[16]  A. McGuire,et al.  Global climate change and terrestrial net primary production , 1993, Nature.

[17]  Vladimir E. Romanovsky,et al.  Thawing of the Active Layer on the Coastal Plain of the Alaskan Arctic , 1997 .

[18]  H. H. Shugart,et al.  AVHRR-derived fire frequency, distribution and area burned in Siberia , 2004 .

[19]  F. Chapin,et al.  Permafrost and the Global Carbon Budget , 2006, Science.

[20]  A. McGuire,et al.  Modeling soil thermal and carbon dynamics of a fire chronosequence in interior Alaska , 2002 .

[21]  W. Schlesinger.  Biogeochemistry: An Analysis of Global Change , 1991 .

[22]  R. B. Jackson,et al.  THE VERTICAL DISTRIBUTION OF SOIL ORGANIC CARBON AND ITS RELATION TO CLIMATE AND VEGETATION , 2000 .

[23]  F. Woodward,et al.  Global response of terrestrial ecosystem structure and function to CO2 and climate change: results from six dynamic global vegetation models , 2001 .

[24]  Mingkui Cao,et al.  Global carbon exchange and methane emissions from natural wetlands : Application of a process-based model , 1996 .

[25]  C. Potter.  An ecosystem simulation model for methane production and emission from wetlands , 1997 .

[26]  E. Kasischke,et al.  Fire, Global Warming, and the Carbon Balance of Boreal Forests , 1995 .

[27]  Philippe Ciais,et al.  Transcom 3 inversion intercomparison: Model mean results for the estimation of seasonal carbon sources and sinks , 2004, Global Biogeochemical Cycles.

[28]  John S. Kimball,et al.  Importance of recent shifts in soil thermal dynamics on growing season length, productivity, and carbon sequestration in terrestrial high‐latitude ecosystems , 2006 .

[29]  R. Dargaville,et al.  Carbon cycling in extratropical terrestrial ecosystems of the Northern Hemisphere during the 20th century: a modeling analysis of the influences of soil thermal dynamics , 2003 .

[30]  J. Randerson,et al.  Continental-Scale Partitioning of Fire Emissions During the 1997 to 2001 El Niño/La Niña Period , 2003, Science.

[31]  Jerry M. Melillo,et al.  Soil Warming and Carbon-Cycle Feedbacks to the Climate System , 2002, Science.

[32]  Stephen Sitch,et al.  Methane flux from northern wetlands and tundra : An ecosystem source modelling approach , 1996 .

[33]  Mingkui Cao,et al.  Global methane emission from wetlands and its sensitivity to climate change , 1998 .

[34]  Taro Takahashi,et al.  Towards robust regional estimates of CO2 sources and sinks using atmospheric transport models , 2002, Nature.

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

[36]  C. Tucker,et al.  A large carbon sink in the woody biomass of Northern forests , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[37]  P. Ciais,et al.  A large Northern Hemisphere terrestrial CO_2 sink indicated by the C^ /C^ ratio of atmospheric CO_2. , 1995 .

[38]  P. Goovaerts,et al.  Uncertainty in estimating carbon emissions from boreal forest fires , 2004 .

[39]  Robert J. Scholes,et al.  The Carbon Cycle and Atmospheric Carbon Dioxide , 2001 .

[40]  Philippe Ciais,et al.  Inverse modeling of annual atmospheric CO2 sources and sinks , 1999 .

[41]  Andrei P. Sokolov,et al.  Linking a global terrestrial biogeochemical model and a 2‐dimensional climate model: implications for the global carbon budget , 1997 .

[42]  J. Melillo,et al.  Multi-gas assessment of the Kyoto Protocol , 1999, Nature.

[43]  J. Hansen,et al.  Global warming in the twenty-first century: an alternative scenario. , 2000, Proceedings of the National Academy of Sciences of the United States of America.

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

[45]  P. Ciais,et al.  A Large Northern Hemisphere Terrestrial CO2 Sink Indicated by the 13C/12C Ratio of Atmospheric CO2 , 1995, Science.

[46]  Andrei P. Sokolov,et al.  Transient climate change and net ecosystem production of the terrestrial biosphere , 1998, Global Biogeochemical Cycles.

[47]  D. Schimel,et al.  Terrestrial ecosystems and the carbon cycle , 1995 .