fires and the contemporary global carbon cycle
DESCRIPTION
Fires and the Contemporary Global Carbon Cycle Guido van der Werf (Free University, Amsterdam, Netherlands) In collaboration with: Jim Randerson (UCI, CA, USA) Louis Giglio (SSAI, MD, USA) Prasad Kasibhatla (Duke University, NC, USA) Jim Collatz (NASA GSFC, MD, USA). Main Objectives - PowerPoint PPT PresentationTRANSCRIPT
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Fires and the Contemporary Global Carbon Cycle
Guido van der Werf (Free University, Amsterdam, Netherlands)
In collaboration with:
Jim Randerson (UCI, CA, USA)
Louis Giglio (SSAI, MD, USA)
Prasad Kasibhatla (Duke University, NC, USA)
Jim Collatz (NASA GSFC, MD, USA)
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Main Objectives
1. Quantify the contemporary amount of biomass burned on a global scale
2. Assess the role of biomass burning in the global CO2 and CH4 cycle
3. Determine the climate sensitivity of biomass burning
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‘Classical’ approach: Emissions = Σx,t A × B × CC × EF
Giglio et al, submitted to ACPD
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Net PrimaryProduction
Allocation=f (treecover)
AbovegroundBiomass C
BelowgroundBiomass C
Combustion
BelowgroundLitter C
AbovegroundLitter C
f(A,CC,M) f(A,CC)
Respiration
Fuelwoodcollection
Herbivoreconsumption
A = area burnt
CC = combustion completeness
M = fire induced mortality
Fires embedded in the CASA satellite-driven biogeochemical model
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Annual fire emissions, averaged over the 1997 – 2004 period
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Annual fire emissions as percentage of NPP, averaged over the 1997 – 2004 period
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Fuel consumption as calculated by CASA
Emission (g) per m2 burned
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On a global scale, IAV in burned area and emissions are decoupled
BA driven by savannas
Emissions driven by forest fires (including deforestation)
1997 peat burning in Asia
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Observed CO anomalies
Boreal region CO (forward modeling)
Atmospheric CO as a constrain on fire emissions
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• CO: forward modeling optimized in inversion to fit observations
• CO2: fires explain ~2/3 of the growth rate anomaly
(60% SE-Asia, 30% C+S America, 10% Boreal)
• CH4: fires explain most of the growth rate anomaly.
Contribution of IAV in fire activity to CO2 and CH4 growth rates
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Mismatch in seasonality between top-down and bottom-up observations (southern Africa)
Atmosphere: peak in September - October
Satellite surface observations: peak in June – July - August
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Effect of IAV in precipitation on fire activity
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Concluding remarks
1. Global (vegetation) fire emissions as calculated by our modeling framework is ~2.5 Pg C / year, largest uncertainties in deforestation regions
2. IAV in fire emissions contributed significantly to variability in the 1997-2001 growth rate of CO2 and CH4.
3. IAV in fire emissions is dominated by IAV in forest fires. Implications:
• IAV in burned area and emissions are decoupled
• IAV in CO and CH4 is larger than IAV in C or CO2
4. (Multi-specie) inversions and high resolution (deforestation) fire modelling ideally employed to further improve estimates