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Coastal Carbon Sinks and Sources Preliminary Analysis Dr Stephen Crooks Climate Change Director, ESA PWA Oceans Day at COP16, Cancun Linking the Science and Economics of Blue Carbon December 4 st 2010. High Preservation Potential. Carbon Burial and Ecosystem Area.
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Coastal Carbon Sinks and SourcesPreliminary AnalysisDr Stephen CrooksClimate Change Director, ESA PWAOceans Day at COP16, Cancun Linking the Science and Economics of Blue CarbonDecember 4st 2010.
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
Unaccounted CO2 Emissions from Drained Wetlands Worldwide 0.3 GtCO2 >10GtCO2? 1.4 GtCO2
CO2 Emissions from Drained Wetlands (Preliminary Estimates)
Estimates of Coastal Carbon Pool Size 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
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.
Stephen Crooks Climate Change Director, ESA PWA s.crooks@pwa-ltd.com 415 262 2300
Peat Accumulation with Sea Level Rise McKee & Vervaeke, 2009
Subsidence Reversal and Carbon Sequestration Net Sequestration: 62 tCO2/ ha/yr Sequest: 44 tCO2 / ha / yr Emission: 18 tCO2 / ha / yr
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 Emissions: 0.25 MtCO2 / km2 / meter depth of soil In peaty wetlands 1 m soils may be lost in >2 decades after drainage
Subsidence of Drained Wetlands: Malaysia Average rate of subsidence per year