methane
; snow
; surface water
; methane
; soil
; air temperature
; arctic tundra
; Article
; autumn
; exhaust gas
; global climate
; greenhouse gas
; growing season
; methanogenesis
; microbial metabolism
; oxidation
; permafrost
; priority journal
; sea ice
; snow cover
; soil temperature
; summer
; surface property
; surface soil
; temperature sensitivity
; United States
; warming
; wetland
; winter
; Arctic
; cold
; environmental monitoring
; season
; soil
; theoretical model
; tundra
; Arctic Regions
; Cold Temperature
; Environmental Monitoring
; Methane
; Models, Theoretical
; Seasons
; Soil
; Tundra
; Wetlands
英文摘要:
Arctic terrestrial ecosystems are major global sources of methane (CH4); hence, it is important to understand the seasonal and climatic controls on CH4 emissions from these systems. Here, we report year-round CH4 emissions from Alaskan Arctic tundra eddy flux sites and regional fluxes derived from aircraft data. We find that emissions during the cold season (September to May) account for ≥50% of the annual CH4 flux, with the highest emissions from noninundated upland tundra. A major fraction of cold season emissions occur during the "zero curtain" period, when subsurface soil temperatures are poised near 0°C. The zero curtain may persist longer than the growing season, and CH4 emissions are enhanced when the duration is extended by a deep thawed layer as can occur with thick snow cover. Regional scale fluxes of CH4 derived from aircraft data demonstrate the large spatial extent of late season CH4 emissions. Scaled to the circumpolar Arctic, cold season fluxes from tundra total 12 ± 5 (95% confidence interval) Tg CH4 y-1, ~25% of global emissions from extratropical wetlands, or ~6% of total global wetland methane emissions. The dominance of late-season emissions, sensitivity to soil environmental conditions, and importance of dry tundra are not currently simulated in most global climate models. Because Arctic warming disproportionally impacts the cold season, our results suggest that higher cold-season CH4 emissions will result from observed and predicted increases in snow thickness, active layer depth, and soil temperature, representing important positive feedbacks on climate warming.
Zona, D., Department of Biology, San Diego State University, San Diego, CA 92182, United States, Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, United Kingdom; Gioli, B., Institute of Biometeorology, National Research Council, Firenze, 50145, Italy; Commane, R., School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, United States; Lindaas, J., School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, United States; Wofsy, S.C., School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, United States; Miller, C.E., Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109-8099, United States; Dinardo, S.J., Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109-8099, United States; Dengel, S., Department of Physics, University of Helsinki, Helsinki, FI-00014, Finland; Sweeney, C., Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80304, United States, Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305, United States; Karion, A., Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80304, United States; Chang, R.Y.-W., School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, United States, Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada; Henderson, J.M., JAtmospheric and Environmental Research, Inc., Lexington, MA 02421, United States; Murphy, P.C., Department of Biology, San Diego State University, San Diego, CA 92182, United States; Goodrich, J.P., Department of Biology, San Diego State University, San Diego, CA 92182, United States; Moreaux, V., Department of Biology, San Diego State University, San Diego, CA 92182, United States; Liljedahl, A., Water and Environmental Research Center, University of Alaska Fairbanks, Fairbanks, AK 99775-7340, United States, International Arctic Research Center, University of Alaska Fairbanks, Fairbanks, AK 99775-7340, United States; Watts, J.D., Numerical Terradynamic Simulation Group, College of Forestry and Conservation, University of Montana, Missoula, MT 59812, United States; Kimball, J.S., Numerical Terradynamic Simulation Group, College of Forestry and Conservation, University of Montana, Missoula, MT 59812, United States; Lipson, D.A., Department of Biology, San Diego State University, San Diego, CA 92182, United States; Oechel, W.C., Department of Biology, San Diego State University, San Diego, CA 92182, United States, Department of Earth, Environment and Ecosystems, Open University, Milton Keynes, MK7 6AA, United Kingdom
Recommended Citation:
Zona D.,Gioli B.,Commane R.,et al. Cold season emissions dominate the Arctic tundra methane budget[J]. Proceedings of the National Academy of Sciences of the United States of America,2016-01-01,113(1)