Transcript Slide 1

Terrestrial Carbon Sequestration
Adrian Martin
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Global terrestrial C budgets
Historical C emissions from land use change
Global potential for LULUCF sequestration
Reforestation
Managing agricultural lands
Institutional framework: Kyoto and CDM
Social issues
IIED (2002)
Carbon cycling on land
270 PgC/yr dissolved in leaf water
~ 1/3 atmospheric C
>½ directly released
to atmosphere
120PgC/yr fixed through
Photosynthesis
= Gross Primary Productivity
60Pg/yr Respired by plants
60Pg/yr plant growth
= Net Primary Productivity
60Pg/yr Net Primary Productivity
Heterotrophic respiration
Bacteria, fungi
Herbivores
Net Ecosystem Productivity
Releases through fire,
harvests, soil erosion, …
Net Biome Production
Net Ecosystem Productivity
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Tropical Forests: 0.7- 5.9 MgC/ha/yr
Temperate forests: 0.8 – 7.0 MgC/ha/yr
Boreal forests: (<0?) – 2.5 MgC/ha/yr
(IPCC 2001)
Global C02 Budgets (PgC/yr)
1980s
1990s
Atmosphere Increase
3.3 ± 0.1
3.2 ± 0.1
Emissions (fossil fuel, cement)
5.4 ± 0.3
6.3 ± 0.4
Ocean-atmosphere flux
- 1.9 ± 0.6
-1.7 ± 0.5
Land-atmosphere flux
(net biome production)
-0.2 ± 0.7
-1.4 ±0.7
- Land use change
1.7
- Residual terrestrial sink
-1.9
Historical Losses of Terrestrial Carbon through
Land Use Change
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Houghton (1990) estimates 121PgC lost 1850 – 1990
De Fries et al (1999) further 60PgC lost prior to 1850
Total 180PgC (280 from fossil fuels)
Approx 40% of this in atmosphere
Substantial (but ultimately limited) opportunities for
modifying above and below ground carbon storage
Deforestation (cont.)
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Deforestation responsible for estimated 90% of
land use change emissions since 1850
FAO (2001) Global Forest Resources
Assessment 2000:
Gross annual loss 1990-2000: 14.6 million ha.
Net annual loss 1990-2000: 9.4million ha.
Forest Area Changes 1990-2000
Tropical
Natural Forest
(Million Ha)
Non-tropical
1990
2000
1990
2000
1945
1803
1863
1879
68
107
119
Plantation Forest 48
(Million Ha)
Source: FAO 2001
Main cause of loss in tropical areas: conversion to agriculture
Global Potential: LULUCF
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IPCC (1996 SAR) slowing deforestation and promoting
reforestation could increase carbon stocks by 60-87PgC 19952050
IPCC (2000 SRLULUCF) various management options could
lead to global land-atmosphere flux of -1.3PgC/yr in 2010 and
-2.5PgC/yr in 2040
Plantations:
Coniferous AUS & NZ:
Coniferous EUR & US:
Canada and former SU:
Tropical:
10 t/ha/yr
1.5 - 4.5 t/ha/yr
0.9 –1.2 t/ha/yr
6.4 – 10 t/ha/yr
Biomass
Above
Ground
Litter/woody
debris
Below
Ground
Short
Term
Long
Term
Soil
Organic
Matter
Wood
Products
&
Landfill
Cultivated
land→ Forest
↑
↑
-
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↑
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Non-cultivated
land→ Forest
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-
↑
?
↑
IPCC 2000 SRLULUCF, Table 3-6
Repositories for extra carbon storage in terrestrial ecosystems
Repository
Fraction
Examples
Mean Residence
Time (MRT)
Biomass
Woody
Tree boles
Decades to centuries
Non-woody
Crops/leaves
Months to years
Litter
Surface litter, crop residues
Months to years
Active
Partially decomposed litter; Years to decades
carbon in macro-aggregates
Soil organic
matter
Stable
Products
Wood
Paper, cloth
grains
waste
Stabilised by clay;
chemically recalcitrant
carbon; charcoal
Centuries to
millennium
Structural, furniture
Paper products, clothing
Food and feed grain
landfill
Decades to centuries
Months to decades
Weeks to years
Months to decades
Predicted responses to different pools of soil organic matter for
agricultural land converted to forest in northeastern United States of
America (Gaudinski et al. 2000, in SRLULUCF)
Carbon sequestration through reforestation in
the tropics
80 year average:
2.36Mg/ha/yr
First 20 years:
6.17 Mg/ha/yr
Silver et al (2000)
100 year average:
0.41 Mg/ha/yr
First 20 years:
1.30 Mg/ha/yr
Silver et al (2000)
Silver et al (2000)
Can sequestration continue beyond 80 years?
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One way is to harvest biomass for energy
The other is to ensure wood products have a long residence time
Paper products like
packaging, newspapers,
magazines
0.5
Paper products like books
15
Fruewald & Scharai-Rad
(2000)
Furniture
20
Fences, garden products etc
20
NB The fate of stored
carbon in wood products
is poorly known
Railway sleepers,
transmission poles
40
Timber in buildings
75
Average estimated
lifetime of wooden
products [Germany]
Changing agricultural practices for
below ground carbon storage
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Historical loss of soil C through oxidation~ 50 PgC
(Ingram & Fernandes, 2001)
Average loss of carbon from top 100 cm of soil following conversion to
agriculture = 15-40%
Restoration possible through land use change and land management
Global potential for C sequestration in agricultural soils 20-30 PgC over 50100 years. (Paustian et al, 1997, cited in Ingram & Fernandes)
Global sequestration from improved management of degraded lands 0.6 – 2
PgC/yr (Batjes, 1999, cited in Olsson & Ardo, 2002)
Carbon sequestration situation against soil organic carbon level.
Source: Ingram & Fernandes (2001)
Main Issues
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Soil erosion (especially
loss of clay content)
Oxidation of carbon
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Tillage
Temperature (e.g.
reduced canopy)
Removal of organic
residues
Drainage (aeration)
Management Options
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No tillage
Change of crops (raise
NPP)
Fertiliser
Land use change –
agroforestry, grassland
Fallow with
grasses/legumes
Grazing of rangelands (see
Schuman et al, 2002)
Olsson & Ardo (2002) case study from Sudan
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Modelling of 6 different management systems in
Sudanese cropland
System
Soil carbon in 2100
(gC m-2)
No change
70
5:6 crop: fallow
115
5:10 crop: fallow
128
5:15 crop: fallow
163
5:20 crop: fallow
170
Grazing only
245
Institutional Basis
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Kyoto article 3 “removals by sinks resulting from direct human-induced
land-use change and forestry activities, limited to afforestation,
reforestation and deforestation since 1990, measured as verifiable changes
in carbon stocks in each commitment period, shall be used to meet the
commitments under this Article….”
Other sinks (such as agricultural soils may be included in the future)
6th COP (resumed July 2001) agreement that reforestation and afforestation
allowed under Clean Development Mechanism.
CDM – allows developed countries to meet their own commitments by
funding emission reduction or carbon sequestration projects in developing
countries.
Limited to 1% of a country’s baseline emissions (i.e. can meet about 20%
of their reduction through CDM forestry projects).
Eligible Land Use Activities in the CDM. Source: IIED 2002
Sequestration: a few concerns
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Verification issues and transaction costs
What kind of forestry?
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Large-scale?
Monocultures
Fast-growing exotics?
Whose development priorities?
Will sinks solve the problem?
Global feedbacks
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FAO (2001) Global Forest Resources Assessment 2000,
www.fao.org/forestry/fo/fra/main/index.jsp
Fruehwald, A. & Scharai-Rad (2000) Wood products as carbon sinks: a methodological
approach,www.bib.fsagx.ac.be/coste21/ftp/2001-04-26/sharai-rad-sum.pdf
IPCC (2001) Climate Change 2001: the scientific basis. www.grida.no/climate/ipcc
IPCC (2000) Special Report on Land Use, Land Use Change and Forestry
IPCC (2001) Climate Change 2001: Mitigation. Section 4. Technological and Economic
Potential of Options to Enhance, Maintain, and Manage Biological Carbon Reservoirs and
Geo-engineering.
IIED (2002) Laying the Foundations for Clean Development: preparing the land use sector: a
quick guide to the Clean Development Mechanism, London: International Institute for
Environment and Development, www.cdmcapacity.org
Ingram, J. & Fernandes, E. (2001) Managing carbon sequestration in soils: concepts and
terminology, Agriculture, Ecosystems and Environment, 87, 111-117.
Schuman, G., Janzen, H. & Herrick, J. (2002) Soil carbon dynamics and potential carbon
sequestration by rangelands, Environmental Pollution, 116, 391-396
Silver, W., Ostertag, R. & Lugo, A. (2000) The potential for carbon sequestration through
reforestation of abandoned tropical agricultural and pasture lands, restoration Ecology, 8 (4),
394-407.
Olsson, L. & Ardo, J. (2002) Soil carbon sequestration in degraded semiarid agro-ecosystems
– perils and potentials, Ambio 30 (6), 471-477.
Seely, B., Welham, C., Kimmins, H. (2002) ‘Carbon sequestration in a boreal forest
ecosystem: results from the ecosystem simulation model, FORECAST’, Forest Ecology and
Management 169, 123-135
Ridgwell, A., Maslin, M. & Watson, A. (2002) Reduced effectiveness of terrestrial carbon
sequestration due to an antagonistic response of ocean productivity, Geophysical Research
Letters, 29 (6), 19