Biogeochmical Interactions and Feedbacks in the Permafrost Regions Martin H eimann Max-Planck-Institute for Biogeochemistry, J ena, Germany martin.heimann@ bgc-jena.mpg.de 1
Interactions between physical climate system and biology Landvegetation Marine biota Surface color (Albedo) Surface roughness Surface color (Albedo) Biophysical feedbacks Evapotranspiration control Turbidity (Energy absorption) Soil moisture Biogeochemical Emission and absorption of greenhouse gases feedbacks Emission and absorption of aerosols and aerosol precursors 2
The Current Carbon Cycle 3
Recent history of atmospheric CO 2 und O 2 concentration Data: R. Keeling, SIO 4
Temporal Evolution of the Global Carbon Balance Implied Landbiosphere Land Use Uptake Change Flux Inferred N et Landbiosphere Fossil Fuel Emissions Atmosphere (direct observations) O cean (direct observations, modeled) M arland et al. 2005, BP 2006, Hougthon et al., 2006 in prep., Keeling et al., 2005 (updated), Wetzel et al., 2005 5
Δ N atm Q emiss Annual estimates D ecadal average + s.d. 6
Carbon Cycle - Climate System Feedbacks Emissions from CO2 burning of fossil Climate Atmosphere fuels and cement production Changes in landuse and land management Landbiosphere Ocean 7
Coupled Carbon Cycle - Climate Model Simulation Experiments (C 4 MIP) 11 models, SRES-A2 emission pro fi le C 4 M IP Simulations, Friedlingstein et al., 2006 8
Simulated Changes in Carbon Storage Hadley Center Model 1860-2100 Carbon Cycle “Hotspots”: 9
Simulated Changes in Carbon Storage Hadley Center Model 1860-2100 Carbon Cycle “Hotspots”: Boreal Forests, Tundra (Permafrost) 9
Simulated Changes in Carbon Storage Hadley Center Model 1860-2100 Carbon Cycle “Hotspots”: 9
Simulated Changes in Carbon Storage Hadley Center Model 1860-2100 Carbon Cycle “Hotspots”: Tropical Ecosystems 9
Simulated Changes in Carbon Storage Hadley Center Model 1860-2100 Carbon Cycle “Hotspots”: 9
Simulated Changes in Carbon Storage Hadley Center Model 1860-2100 Carbon Cycle “Hotspots”: Soils 9
Regional Responses: HadCM3LC and MPI Model Simulations Tropics N orthern Extratropics Climate effect N PP N EP C 4 M IP Simulations, Friedlingstein et al., 2006 10
Global Carbon Cycle - Climate Feedbacks 11
Global Carbon Cycle - Climate Feedbacks • D ominance of terrestrial sources and sinks 11
Global Carbon Cycle - Climate Feedbacks • Dominance of terrestrial sources and sinks • Tropics dominate terrestrial response 11
Global Carbon Cycle - Climate Feedbacks • Dominance of terrestrial sources and sinks • Tropics dominate terrestrial response • Models assume substantial CO 2 fertilization: 11
Global Carbon Cycle - Climate Feedbacks • Dominance of terrestrial sources and sinks • Tropics dominate terrestrial response • Models assume substantial CO 2 fertilization: ∆ NP P NP P 0 β = = 0 . 2 − 0 . 6 ∆ C C 0 11
Global Carbon Cycle - Climate Feedbacks • Dominance of terrestrial sources and sinks • Tropics dominate terrestrial response • Models assume substantial CO 2 fertilization: ∆ NP P NP P 0 β = = 0 . 2 − 0 . 6 ∆ C C 0 • Carbon cycle - climate feedback gain, range of C 4 MIP models: 11
Global Carbon Cycle - Climate Feedbacks • Dominance of terrestrial sources and sinks • Tropics dominate terrestrial response • Models assume substantial CO 2 fertilization: ∆ NP P NP P 0 β = = 0 . 2 − 0 . 6 ∆ C C 0 • Carbon cycle - climate feedback gain, range of C 4 MIP models: • 4 - 20% (10 models), 11
Global Carbon Cycle - Climate Feedbacks • Dominance of terrestrial sources and sinks • Tropics dominate terrestrial response • Models assume substantial CO 2 fertilization: ∆ NP P NP P 0 β = = 0 . 2 − 0 . 6 ∆ C C 0 • Carbon cycle - climate feedback gain, range of C 4 MIP models: • 4 - 20% (10 models), • 31% (HadCM3LC) 11
Global Carbon Cycle - Climate Feedbacks • Dominance of terrestrial sources and sinks • Tropics dominate terrestrial response • Models assume substantial CO 2 fertilization: ∆ NP P NP P 0 β = = 0 . 2 − 0 . 6 ∆ C C 0 • Carbon cycle - climate feedback gain, range of C 4 MIP models: • 4 - 20% (10 models), • 31% (HadCM3LC) • Limitations: Land use effects, permafrost and wetlands 11
Anticipated critical boreal and arctic changes • W arming ⇒ lengthening of vegetation period ⇒ increase in carbon uptake • W arming ⇒ enhanced soil decomposition ⇒ enhanced CO 2 release • W arming + drying ⇒ wetland degradation • W arming + drying ⇒ changes in fi re regimes • W arming ⇒ permafrost carbon degradation ⇒ CO 2 , CH 4 • W arming + hydrological regime shifts ⇒ ecosystem composition changes ⇒ shifts in carbon balance • Antropogenic impacts: Logging, fi re, agriculture 12
Permafrost - a missing feedback link in present Earth System Models Cherskii (68.5N ,161.2E) 13
ermafrost Extent 14
ermafrost Extent Cherskii 14
O2 CO2 CH4 Heat Permafrost Surface Respiration Thawing Aerated Zone Heat Water Table Car bon Water Flooded Zone Melting T=0C Frozen Carbon Permafrost Zimov et al., 1993 15
“Critical” Carbon Content ρ w L = ρ C γ kgC -1 γ ~12.5 MJ • Caloric heat release by respiration ~10 kgC m-3 ρ C • Soil carbon content • ρ w Soil water (ice) content 35% � 350 kg m -3 • Fusion energy kg-1 L 0.334 MJ Typical values in permafrost 16
Simulated Depth of Permafrost Thawing Zone with W arming Scenario of 0.1K /yr W ith heating feedback Depth N o feedback 17
1-d Model of CH 4 , CO 2 and O 2 in permafrost soil Fo Figure 1. Scheme of the permafrost carbon cycle model Khvorostyanov et al., Tellus, 2007 18
Modelled soil processes • Heat conduction • Simple soil hydrology • Soil organic matter decomposition • O rganic matter decomposition to CO 2 • Methanogenesis and methanotrophy • Gas fl uxes: O 2 , CO 2 , CH 4 by diffusion, ebullition, plant transport Khvorostyanov et al., Tellus, 2007 19
Model predicted CH 4 fl ux evaluation Cherskii site (68.5N ,161.2E) Khvorostyanov et al., Tellus, 2007 20
KHVOROSTYANOV ET AL Biogeochemical Feedbacks in Permafrost Soils Khvorostyanov et al., Tellus, 2007 21
Idealized step-change 50yr warming experiment eer R 22
Atmospheric step change warming experiment (+5 °C at model year 1000) For Peer W ith metabolic heat generation W ithout metabolic heat generation Fo (a) Soil temperature ( ◦ C): talik formation when decomposi- (c) Soil temperature ( ◦ C): no talik formation when decompo- tion heat is ’On’. Contour interval is 4 ◦ C sition heat is ’Off’. Contour interval is 4 ◦ C Talik formation 23
Response to F (b) Soil oxygen in g per m 3 soil (a) Soil temperature ( ◦ C) o 50 year warming r P experiment e e r R e v (c) Soil carbon density (kgC m − 3 ) (d) Methanogenesis (positive values) and methanotrophy (neg- i ative values) rates (gC m − 3 day − 1 ) e w Khvorostyanov et al., Tellus, 2007 (e) Soil respiration rate (gC m − 3 day − 1 ) (f) Soil methane in g per m 3 soil 24
Limitations • 1-d approach • Hydrology • Microbiological decomposition functions 25
W hy Siberia? • Siberian boreal forest is a signi fi cant component of the global carbon cycle: • ~ 10% of global terrestrial carbon (vegetation+soils) • ~ 5-10% of global terrestrial productivity • ~ 65% of Siberian forests contain permafrost • Modest anthropogenic impacts • Expected large climate change impacts • Large interannual climate variability • Fire a crucial disturbance factor • W etlands - potential for emissions of CO 2 and/or CH4: ~ 83 PgC • Permafrost soil carbon: 400PgC (global), vulnerable: 5PgC (20yr), 100PgC (100yr) 26
Recommend
More recommend
