Biogeochmical Interactions and Feedbacks in the Permafrost Regions - - PowerPoint PPT Presentation

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Biogeochmical Interactions and Feedbacks in the Permafrost Regions - - PowerPoint PPT Presentation

Jun 26, 2023 232 likes •636 views

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

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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

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Interactions between physical climate system and biology

Landvegetation Marine biota Biophysical feedbacks Surface color (Albedo) Surface roughness Evapotranspiration control Soil moisture Surface color (Albedo) Turbidity (Energy absorption) Biogeochemical feedbacks Emission and absorption of greenhouse gases Emission and absorption of aerosols and aerosol precursors

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The Current Carbon Cycle

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Data: R. Keeling, SIO

Recent history of atmospheric CO 2 und O 2 concentration

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Temporal Evolution of the Global Carbon Balance

O cean (direct observations, modeled) Atmosphere (direct observations) Fossil Fuel Emissions Inferred N et Landbiosphere Land Use Change Flux Implied Landbiosphere Uptake

M arland et al. 2005, BP 2006, Hougthon et al., 2006 in prep., Keeling et al., 2005 (updated), Wetzel et al., 2005

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ΔNatm Qemiss

D ecadal average + s.d. Annual estimates

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Carbon Cycle - Climate System Feedbacks

CO2 Atmosphere Ocean Landbiosphere Climate Emissions from burning of fossil fuels and cement production Changes in landuse and land management 7

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Coupled Carbon Cycle - Climate Model Simulation Experiments (C 4MIP)

C4M IP Simulations, Friedlingstein et al., 2006

11 models, SRES-A2 emission profile

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Simulated Changes in Carbon Storage Hadley Center Model 1860-2100 Carbon Cycle “Hotspots”:

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Simulated Changes in Carbon Storage Hadley Center Model 1860-2100 Carbon Cycle “Hotspots”:

Boreal Forests, Tundra (Permafrost)

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Simulated Changes in Carbon Storage Hadley Center Model 1860-2100 Carbon Cycle “Hotspots”:

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Simulated Changes in Carbon Storage Hadley Center Model 1860-2100 Carbon Cycle “Hotspots”:

Tropical Ecosystems

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Simulated Changes in Carbon Storage Hadley Center Model 1860-2100 Carbon Cycle “Hotspots”:

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Simulated Changes in Carbon Storage Hadley Center Model 1860-2100 Carbon Cycle “Hotspots”:

Soils

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Regional Responses: HadCM3LC and MPI Model Simulations

N PP N EP Tropics N orthern Extratropics

C4M IP Simulations, Friedlingstein et al., 2006

Climate effect

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Global Carbon Cycle - Climate Feedbacks

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Global Carbon Cycle - Climate Feedbacks

  • D ominance of terrestrial sources and sinks

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Global Carbon Cycle - Climate Feedbacks

  • Dominance of terrestrial sources and sinks
  • Tropics dominate terrestrial response

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Global Carbon Cycle - Climate Feedbacks

  • Dominance of terrestrial sources and sinks
  • Tropics dominate terrestrial response
  • Models assume substantial CO 2 fertilization:

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Global Carbon Cycle - Climate Feedbacks

  • Dominance of terrestrial sources and sinks
  • Tropics dominate terrestrial response
  • Models assume substantial CO 2 fertilization:

β =

∆NP P NP P0 ∆C C0

= 0.2 − 0.6

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Global Carbon Cycle - Climate Feedbacks

  • Dominance of terrestrial sources and sinks
  • Tropics dominate terrestrial response
  • Models assume substantial CO 2 fertilization:

β =

∆NP P NP P0 ∆C C0

= 0.2 − 0.6

  • Carbon cycle - climate feedback gain, range of C4MIP models:

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Global Carbon Cycle - Climate Feedbacks

  • Dominance of terrestrial sources and sinks
  • Tropics dominate terrestrial response
  • Models assume substantial CO 2 fertilization:

β =

∆NP P NP P0 ∆C C0

= 0.2 − 0.6

  • Carbon cycle - climate feedback gain, range of C4MIP models:
  • 4 - 20% (10 models),

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Global Carbon Cycle - Climate Feedbacks

  • Dominance of terrestrial sources and sinks
  • Tropics dominate terrestrial response
  • Models assume substantial CO 2 fertilization:

β =

∆NP P NP P0 ∆C C0

= 0.2 − 0.6

  • Carbon cycle - climate feedback gain, range of C4MIP models:
  • 4 - 20% (10 models),
  • 31% (HadCM3LC)

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Global Carbon Cycle - Climate Feedbacks

  • Dominance of terrestrial sources and sinks
  • Tropics dominate terrestrial response
  • Models assume substantial CO 2 fertilization:

β =

∆NP P NP P0 ∆C C0

= 0.2 − 0.6

  • Carbon cycle - climate feedback gain, range of C4MIP models:
  • 4 - 20% (10 models),
  • 31% (HadCM3LC)
  • Limitations:

Land use effects, permafrost and wetlands

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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 fire 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, fire, agriculture

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Permafrost - a missing feedback link in present Earth System Models Cherskii (68.5N ,161.2E)

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ermafrost Extent

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Cherskii

ermafrost Extent

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Permafrost Water Flooded Zone Surface Car bon Frozen Carbon Aerated Zone CH4 CO2 Respiration Heat Melting Heat Water Table T=0C O2

Zimov et al., 1993

Permafrost Thawing

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  • Caloric heat release by respiration
  • Soil carbon content
  • Soil water (ice) content
  • Fusion energy

ρwL = ρCγ

ρw ρC L

γ

~10 kgC m-3 35% 350 kg m-3 ~12.5 MJ kgC -1 0.334 MJ kg-1

“Critical” Carbon Content

Typical values in permafrost

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W ith heating feedback N o feedback

Depth

Simulated Depth of Permafrost Thawing Zone with W arming Scenario of 0.1K /yr

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1-d Model of CH4, CO 2 and O 2 in permafrost soil

Fo

Figure 1. Scheme of the permafrost carbon cycle model

Khvorostyanov et al., Tellus, 2007 18

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Modelled soil processes

  • Heat conduction
  • Simple soil hydrology
  • Soil organic matter decomposition
  • O rganic matter decomposition to CO 2
  • Methanogenesis and methanotrophy
  • Gas fluxes:

O 2, CO 2, CH 4 by diffusion, ebullition, plant transport

Khvorostyanov et al., Tellus, 2007 19

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Khvorostyanov et al., Tellus, 2007

Model predicted CH 4 flux evaluation

Cherskii site (68.5N ,161.2E)

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Biogeochemical Feedbacks in Permafrost Soils

Khvorostyanov et al., Tellus, 2007

KHVOROSTYANOV ET AL

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Idealized step-change 50yr warming experiment

eer R

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Atmospheric step change warming experiment (+5 °C at model year 1000)

Fo

(a) Soil temperature (◦C): talik formation when decomposi- tion heat is ’On’. Contour interval is 4◦C

For Peer

(c) Soil temperature (◦C): no talik formation when decompo- sition heat is ’Off’. Contour interval is 4◦C

W ith metabolic heat generation W ithout metabolic heat generation Talik formation

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Response to 50 year warming experiment

F

  • r

P e e r R e v i e w

(a) Soil temperature (◦C) (b) Soil oxygen in g per m3 soil (c) Soil carbon density (kgC m−3) (d) Methanogenesis (positive values) and methanotrophy (neg- ative values) rates (gC m−3 day−1) (e) Soil respiration rate (gC m−3 day−1) (f) Soil methane in g per m3 soil

Khvorostyanov et al., Tellus, 2007 24

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Limitations

  • 1-d approach
  • Hydrology
  • Microbiological decomposition functions

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W hy Siberia?

  • Siberian boreal forest is a significant 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)

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