Dr Stephen Crooks
Coastal Carbon Sinks and Sources Preliminary Analysis Dr Stephen Crooks Climate Change Director, ESA PWA
UNFCCC COP16, Cancun
Blue Carbon: Valuing CO2 Mitigation by Coastal Marine Systems Sequestration of Carbon Along our Coasts: Are We Missing Major Sinks? December 1st 2010.
Peat Accumulation with Sea Level Rise
McKee & Vervaeke, 2009
High Preservation Potential
Carbon Burial and Ecosystem Area
Drained Wetlands: Very High Emissions
Sacramento - San Joaquin Delta
Emissions from One Drained Wetland Area under agriculture
300,000 acres
Rate of subsidence (in)
1 inch
10 to 15 million tCO2/yr released from Delta 2 GtCO2 release in c.100 years 4000 years of carbon emitted Equiv. carbon held in 50% of California’s forests
Subsidence Reversal and Carbon Sequestration Net Sequestration: 62 tCO2/ ha/yr
Sequest: 44 tCO2 / ha / yr
Emission: 18 tCO2 / ha / yr
Unaccounted CO2 Emissions from Drained Wetlands Worldwide
0.3 GtCO2 1.4 GtCO2
>10GtCO2?
CO2 Emissions from Drained Wetlands (Preliminary Estimates)
Estimates of Coastal Carbon Pool Size Ecosystem
Global Extent (km2)
Annual Rate Of Loss (%)
Tidal Marsh
400,000
1-2
Mangrove
160,000
1-2
Seagrass
300-600,000
1-2
Emissions: 0.1 - 0.25 MtCO2 / km2 / meter depth of soil In peaty wetlands 1 m soils may be lost in >2 decades after drainage Global tidal marsh and mangrove sink at risk: 200 - 600 GtCO2
Coastal Carbon Sinks at Risk
Conclusions • Coastal wetlands hold dense stores of carbon. • Wetlands emit large quantities of CO2 directly to the atmosphere when drained. • Emissions from drained wetlands highest in first few year. Organic soils continue to lose carbon. • Organic rich soils may release centuries to millennia of carbon within a few decades. • Carbon emissions are readily quantifiable. • Emissions from seagrass beds may also be significant but we know less of the quantity and fate of carbon released.
Large-scale Open boundary Emissions Wetland loss: 100 km2 /yr If top 50 cm erodes then 0.3 GtCO2 /yr Released into circulation But what is its fate???
Relationship between watertable depth and CO2 emissions through peat decomposition
Hooijer et al., 2010
Rates of wetland loss Ecosystem
Global Extent (km2)
Annual Rate Of Loss (%)
Tidal Marsh
400,000
1-2
Mangrove
160,000
1-2
Seagrass
300-600,000
1-2
Emissions: 0.25 MtCO2 / km2 / meter depth of soil In peaty wetlands 1 m soils may be lost in >2 decades after drainage
Average rate of subsidence per year
Subsidence of Drained Wetlands: Malaysia
UNFCCC COP16, Cancun
Blue Carbon: Valuing CO2 Mitigation by Coastal Marine Systems Sequestration of Carbon Along our Coasts: Are We Missing Major Sinks? December 1st 2010.
Peat Accumulation with Sea Level Rise
McKee & Vervaeke, 2009
High Preservation Potential
Carbon Burial and Ecosystem Area
Drained Wetlands: Very High Emissions
Sacramento - San Joaquin Delta
Emissions from One Drained Wetland Area under agriculture
300,000 acres
Rate of subsidence (in)
1 inch
10 to 15 million tCO2/yr released from Delta 2 GtCO2 release in c.100 years 4000 years of carbon emitted Equiv. carbon held in 50% of California’s forests
Subsidence Reversal and Carbon Sequestration Net Sequestration: 62 tCO2/ ha/yr
Sequest: 44 tCO2 / ha / yr
Emission: 18 tCO2 / ha / yr
Unaccounted CO2 Emissions from Drained Wetlands Worldwide
0.3 GtCO2 1.4 GtCO2
>10GtCO2?
CO2 Emissions from Drained Wetlands (Preliminary Estimates)
Estimates of Coastal Carbon Pool Size Ecosystem
Global Extent (km2)
Annual Rate Of Loss (%)
Tidal Marsh
400,000
1-2
Mangrove
160,000
1-2
Seagrass
300-600,000
1-2
Emissions: 0.1 - 0.25 MtCO2 / km2 / meter depth of soil In peaty wetlands 1 m soils may be lost in >2 decades after drainage Global tidal marsh and mangrove sink at risk: 200 - 600 GtCO2
Coastal Carbon Sinks at Risk
Conclusions • Coastal wetlands hold dense stores of carbon. • Wetlands emit large quantities of CO2 directly to the atmosphere when drained. • Emissions from drained wetlands highest in first few year. Organic soils continue to lose carbon. • Organic rich soils may release centuries to millennia of carbon within a few decades. • Carbon emissions are readily quantifiable. • Emissions from seagrass beds may also be significant but we know less of the quantity and fate of carbon released.
Large-scale Open boundary Emissions Wetland loss: 100 km2 /yr If top 50 cm erodes then 0.3 GtCO2 /yr Released into circulation But what is its fate???
Relationship between watertable depth and CO2 emissions through peat decomposition
Hooijer et al., 2010
Rates of wetland loss Ecosystem
Global Extent (km2)
Annual Rate Of Loss (%)
Tidal Marsh
400,000
1-2
Mangrove
160,000
1-2
Seagrass
300-600,000
1-2
Emissions: 0.25 MtCO2 / km2 / meter depth of soil In peaty wetlands 1 m soils may be lost in >2 decades after drainage
Average rate of subsidence per year
Subsidence of Drained Wetlands: Malaysia
