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. Decreasing snow cover and sea ice. Increased plant growth; northward migration of tree line. Increased terrestrial precipitation. Destabilization of permafrost.

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 CH 4 and CO 2 emissions.

Impacts on Infrastructure

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

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 Carbon source, 35-43k years old, d13C~-70‰. Walter et al., Nature, Sept Methane Bubbling From Siberian Lakes

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.

Optimized 2001 Emissions TgCH4/yr (Courtesy of P. Bergamaschi) Coal 30,72 (TgCH4/yr) Oil/Gas Enteric Fermentation/Manure Rice Biomass Burning Waste Wetlands Wild Animals 5.00 Termites Soil Oceans 17.00

Wetland Warming CH 4 emissions are very T sensitive. E T = E T 0 Q 10 (T-T 0 /10) where Q 10 = E T+10 /E T Q 10 = 2-15 for CH 4 wetland emissions. Mid-value used for this study.

Estimated Emission Growth Sources: IRRI, EIA Coal 31 TgCH4/yr2%/yr %/yr China 2.7 %/yr India Oil/Gas %/yr NA %/yr Russia 4.0%/yr SH/Mid-East Rice %/yr127 Wetlands (>60N)

Simulated Time Series: Perturbation-Control

Simulated Time Series:

Projected Emission Changes

Detection Changes in CH 4 Growth Rate. Changes in Amplitude or Phase Shifts in the Seasonal Cycle Changes in Spatial Gradients How Useful Are Satellite Column Averages?

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

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

The Annual Cycle Amplitude and Phase

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

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

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 CH 4 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.

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

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