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Increasing Wetland Emissions of Methane From A Warmer Artic: Do we See it Yet?

Increasing Wetland Emissions of Methane From A Warmer Artic: Do we See it Yet?. Lori Bruhwiler and Ed Dlugokencky Earth System Research Laboratory Boulder, Colorado. Arctic Climate Change. Accelerating T increase since early-1990s (>0.3°C decade -1 ) resulting in warming of wetland soils.

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Increasing Wetland Emissions of Methane From A Warmer Artic: Do we See it Yet?

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  1. Increasing Wetland Emissions of Methane From A Warmer Artic: Do we See it Yet? Lori Bruhwiler and Ed Dlugokencky Earth System Research Laboratory Boulder, Colorado

  2. Arctic Climate Change • Accelerating T increase since early-1990s (>0.3°C decade-1) resulting in warming of wetland soils. • Decreasing snow cover and sea ice. • Increased plant growth; northward migration of tree line. • Increased terrestrial precipitation. • Destabilization of permafrost.

  3. Permafrost • Accelerating melting thermokarst formation Expanding wetland area. • Longer active season. • Increased transport DOC to Arctic Ocean. • Changing vegetation affects RF. • Soils contain 500 to 900 Pg C, implying a potential for huge CH4 and CO2 emissions.

  4. Impacts on Infrastructure

  5. Thermokarst Formation • Thermokarst (thaw) lakes migrate naturally and can be accelerated by climate change.

  6. Walter et al., Nature, Sept. 2006 Methane Bubbling From Siberian Lakes • Year-round flux measurements. • Remote sensing, aerial surveys quantify emissions. • 95% emissions from ebullition. • 3.8 TgCH4 yr-1 from Siberian thermokarst lakes • Increased by 58%, from 1974 to 2000. • Carbon source, 35-43k years old, d13C~-70‰.

  7. Simulation of Increased Wetland Emissions from Permafrost Destabilization • Model: TM5- 6x4 Horizontal Resolution, 25 Levels • Constant Sources/ Soil Sink optimized against observations from 2002 (e.g Bergamaschi,2005) • Constant Photochemical Sink with OH optimized against MC observations (courtesy of P. Bergamaschi) • HNH Wetlands - Perturbation Calculated Assuming Q10 Temperature Relationship and Observed Temperature Trends for High Northern Latitudes. Plus projected increases in coal, rice, oil and gas.

  8. Optimized 2001 Emissions 525.63 TgCH4/yr (Courtesy of P. Bergamaschi) Coal 30,72 (TgCH4/yr) Oil/Gas 50.86 Enteric Fermentation/Manure 100.46 Rice 59.74 Biomass Burning 32.30 Waste 73.62 Wetlands 174.49 Wild Animals 5.00 Termites 19.23 Soil -37.79 Oceans 17.00

  9. Wetland Warming CH4 emissions are very T sensitive. • ET = ET0Q10(T-T0/10) where Q10 = ET+10/ET • Q10 = 2-15 for CH4 wetland emissions. Mid-value used for this study.

  10. Estimated Emission GrowthSources: IRRI, EIA Coal 31 TgCH4/yr 2%/yr 40 4.2%/yr China 2.7 %/yr India Oil/Gas 51 0.4%/yr NA 66 2.4%/yr Russia 4.0%/yr SH/Mid-East Rice 60 0.75%/yr 127 Wetlands 45 136 (>60N)

  11. Simulated Time Series: Perturbation-Control

  12. Simulated Time Series:

  13. Simulated Time Series: Projected Emission Changes

  14. Detection • Changes in CH4 Growth Rate. • Changes in Amplitude or Phase Shifts in the Seasonal Cycle • Changes in Spatial Gradients • How Useful Are Satellite Column Averages?

  15. Global Growth Rate No significant Change in Growth Rate. Compensation among emissions changes? Methane could be approaching steady state (Dlugokencky et al., GRL, 2003) Picture the same for Polar Latitude Zone

  16. Simulated Growth Rate Increasing Emissions from Northern Wetlands Should Cause Increases In the Global Growth Rate

  17. The Annual Cycle Amplitude and Phase

  18. Spatial Gradients- The Interpolar Difference Dlugokencky et al., GRL 2003

  19. Simulated Inter-polar Difference The IPD will be a sensitive indicator of increased emissions from High Northern Latitudes

  20. Enhance Detection and Attribution • Add Arctic in situ measurement sites • Cherskii, NE Science Research Station (Siberia) • Tiksi (Siberia), Toolik Lake (Alaska), Eureka (Canada) • Yukon Basin (Alaska,USGS) • Develop robust analytical system • LGR optical CH4 analyzer • Assimilation and Estimation of CH4 fluxes using Ensemble Kalman Filter Method with TM5 • Regression Analysis suggests that current network won’t be able to differentiate emission changes from various sources.

  21. Conclusions • There is currently no evidence from the Cooperative Air Sampling Network of an increase in emissions from the Arctic • Several sensitive diagnostics may be used to detect Permafrost Destabilization in the Arctic

  22. Permafrost *Regions (dry or wet) below 0°C for two consecutive years. *On land *Undersea

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