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Methane Emission from Natural Wetlands in Northern Mid and High Latitudes since 1980s

Methane Emission from Natural Wetlands in Northern Mid and High Latitudes since 1980s. Xiaofeng Xu 1 , Hanqin Tian 1 , Vivienne Payne 2 , Janusz Eluszkiewicz 2 , Lori Bruhwiler 3 , Steve Wofsy 4 1. Auburn University 2. Atmospheric and Environmental Research Inc.

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Methane Emission from Natural Wetlands in Northern Mid and High Latitudes since 1980s

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  1. Methane Emission from Natural Wetlands in Northern Mid and High Latitudes since 1980s Xiaofeng Xu1, Hanqin Tian1, Vivienne Payne2, Janusz Eluszkiewicz2, Lori Bruhwiler3, Steve Wofsy4 1. Auburn University 2. Atmospheric and Environmental Research Inc. 3. National Oceanic and Atmospheric Administration 4. Harvard University

  2. Acknowledgements • Financial support: (NASA projects (ACMAP); DOE: DUKE UN-07-SC-NICCR-1016); NIFA McIntire-Stennis project) • Drs. Mingliang Liu, Chaoqun Lu, Wei Ren, Guangsheng Chen

  3. What is the role of natural wetlands in northern mid and high latitudes in the global methane cycle?

  4. Objectives • To characterize the spatial distribution of CH4 flux in northern mid and high latitudes and its variations over time • To examine the underlying mechanisms of the changes in CH4 flux • factorial contributions (Elevated CO2, Climate variability, Ozone pollution, nitrogen deposition) • To compare with other results • Vs. inverse results & satellite results

  5. Methodology • Model • DLEM: Dynamic Land Ecosystem Model (Tian et al., 2010, Biogeosciences) • Model driving forces • Climate: NCEP II (daily) • Fractional wetland distribution(Aselmann and Crutzen 1989; Lehner and Noll 2004) • Seasonal herbaceous and woody wetlands • Permanent herbaceous and woody wetlands • Others (soil, ozone, nitrogen deposition, CO2, etc)

  6. DLEM Tian et al., 2010

  7. Methane module Xu et al., 2010

  8. Click here to view movie

  9. Changes in CH4 flux over the three decades 1990s to 2000s 1980s to 1990s

  10. Methane emission in Northern mid and high latitudes from 1980 to 2008

  11. Simulation experiments

  12. Climate variability contributed more than 95% to the accumulated CH4 flux

  13. All: simulations with all driving forces changed over time; Climate_only: simulation with climate factor changed while all others unchanged. Climate could explain more than 99% of the interannual variations in methane flux (R2 > 0.99)

  14. Multiple linear regression also indicates that temperature is stronger than precipitation upon controlling regional CH4 flux

  15. Anomaly of CH4 flux during 2005-2007 relative to the average between 1980 and 2008 Temperature anomaly Precipitation anomaly

  16. Comparison with satellite data 2003-2007 average CH4 flux simulated by DLEM 2003-2007 average CH4 flux derived by satellite data and an empirical method (Bloom et al., 2010)

  17. Seasonal comparison with inverse results 2004 Fraserdale, Ontario Miller et al., 2010

  18. Summary • Methane emission from Northern mid and high latitudes showed substantial inter-annual variability during 1980-2008 and a significant increase in the first decade of 21st century • Temperature was the major factor controlling the increase of regional CH4 emission, while precipitation control spatial changes of CH4 flux. • Spatiotemporal patterns of simulated CH4 flux were consistent with other results derived by both bottom-up and top-down approaches

  19. Future work • Development of high-resolution time-series map of natural wetlands • Intensive field observations in natural wetlands • Wetland model improvements and comparisons • Integrative study by combining bottom-up and top-down approaches

  20. Thanks for your attentions!! Questions or comments???

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