1. Terrestrial ecosystems carbon balance in China during 1980s and 1990s
Tao Wang, Shilong Piao, Philippe Ciais
Oct

2. Partial absorption of CO2 at Mauna Loa
Land and ocean carbon sinks
offset climate change
Levin (2012) from Nature
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3. + Fate of Anthropogenic CO2 Emissions (2000-2008) 45% 29% 26%
1.4 Pg C y-1 +
7.7 Pg C y-1
3.0 Pg C y-1
29%
4.1 Pg C y-1
45%
26%
2.3 Pg C y-1
Le Quéré et al. 2009, Nature-geoscience;
Canadell et al. 2007, PNAS, updated
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4. Why do we need regional C budget estimates?
Link regional fluxes to the global increase in CO2
Understand regional processes by comparison between regions
Better predict the future impacts of humans and climate on the C cycle
Help define mitigation policies
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5. It is of critical importance to quantify China’s carbon budget
Large C emissions
2000
China
1600
USA
1200
Carbon Emissions per year
(tons x 1,000,000)
800
India
Russian Fed.
400
Japan
1990 03 05 07 99 01 03 05
2008
Time
Global Carbon Project 2009; Data: Gregg Marland, CDIAC 2009
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6. Afforestation/reforestation projects
China contributed about one quarter of the global plantation area.
Forest plantation benefit net carbon uptake
Kauppi et al., (2006)
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7. Rapid Urbanization Carbon loss from new urban settlements
Carbon gain since movement of rural population to cities have diminished the collection of fuel wood, accelerating the recovery of vegetation
Chinese Population urbanized (%)
Tian et al., (2005)
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8. Pronounced warming trend in China
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9. Dryer in the North, wetter in the South
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10. Significant change in Atmospheric composition
Nitrogen deposition enhances the net carbon fixation
Atmospheric O3 pollution cause a decrease in C storage
Magnani et al. 2007, Nature
Sitch et al. 2007, Nature
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11. Grassland
Shrub
How do vegetation activity and carbon storage respond to these climate and human disturbance?
Forest
Crop
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12. Ensemble Approach Remote-sensing Ecosystem modeling
Atmospheric inverse modeling
Inventory (biomass and soil carbon)
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13. Method 1: Inventory + Satellite
Datasets
1. Forest inventories and field biomass data
~200,000 permanent and temporary sample plots, 5 periods: , , , ,
2. Shrub and Grassland biomass inventory data
3. Cropland SOC survey data, statistics for crop yield, area, and others
4. GIMMS-NDVI dataset
8 km resolution; 15-day;
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14. Method 1: Inventory + Satellite
Forest biomass densitity change
We estimate forest biomass density from timber volume using BEF (Biomass expansion factor), the ratio of biomass to timber volume, expressed as a function of stem volume (x), BEF = a + b/x
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15. Method 1: Inventory + Satellite
Shrub biomass change
We estimate biomass C of shrubs using relationship between aboveground biomass and seasonal NDVI at 34 shrub sites.
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16. Method 1: Inventory + Satellite
Grassland biomass change
We estimate biomass C of grasslands using relationship between aboveground biomass and seasonal NDVI.
The difference of biomass C density between the late 1990s and early 1980s
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17. Method 1: Inventory + Satellite
Soil carbon storage change
Assumption: trends in litter input can be inferred from trends in NDVI, and that changes in decomposition of SOC are driven by temperature and precipitation.
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18. Method 1: Inventory + Satellite
Limitations
Not included wetland; trees out forests (four-side trees and individual tress)
Large uncertainties....
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19. Method 2: Atmospheric inversion
Prior flux information
LMDZ transport model
observations
Optimized fluxes
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20. Method 2: Atmospheric inversion
Limitations
Limited observing sites
Only measure net CO2 flux，and thus need further validation
Uncertainties from human CO2 emissions
Uncertainties from transport model
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21. convection de chaleur sèche
Method 3: Ecosystem model
Température
convection de chaleur sèche
de la surface
Interception par la canopée
Infiltration, stockage, drainage
ruissellement de surface
Evapotranspiration
Humidité de l’air
Précipitation
Solaire et
infra-rouge
Rayonnement
Photosynthèse nette
Respiration de
croissance & maintenance
Allocation des assimilats
litière
Bilan de carbone et de nutriments
Flux de CO2
Concentration en CO2
Vitesse du vent
Turbulence de l’air
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22. Method 3: Ecosystem model
Limitations
Uncertainties due to model parameterizations
Uncertainties from climate driving
Not consider land use change…
To overcome these (Trendy Project)
The same climate forcing
10 ecosystem models
HyLand, Lund–Potsdam–Jena DGVM, ORCHIDEE, Sheffield–DGVM, TRIFFID, LPJ-GUESS, NCAR-CLM4CN, OCN, VEGAS and VISIT
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23. Method 1: Inventory- and satellite- based estimation
Result
Method 1: Inventory- and satellite- based estimation
Forest
Grassland
Crop
Shrub
75±35 Tg C/yr
7±3 Tg C/yr
13±1 Tg C/yr
22±10 Tg C/yr
vegetation
4±4 Tg C/yr
6±1 Tg C/yr
26±11 Tg C/yr
39±9 Tg C/yr
Soil
Wood products
Fire
Bamboo ?
9 Tg C/yr
- 3 Tg C/yr
1±1 Tg C/yr
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24. Method 1: Inventory- and satellite- based estimation
Result
Method 1: Inventory- and satellite- based estimation
Forest
Grassland
Crop
Shrub
75±35 Tg C/yr
7±3 Tg C/yr
13±1 Tg C/yr
22±10 Tg C/yr
vegetation
4±4 Tg C/yr
6±1 Tg C/yr
26±11 Tg C/yr
39±9 Tg C/yr
Soil
Wood products
Fire
Bamboo
186±73 Tg C/yr
9 Tg C/yr
- 3 Tg C/yr
1±1 Tg C/yr
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25. Method 2: Atmosphere inversion estimation
Prior flux information
LMDZ transport model
observations
The mean result of the inversion ensemble over the period is a net CO2 uptake of 350 Tg C/yr.
Optimized fluxes
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26. Chinese terrestrial carbon balance from Method 2
261Tg C/yr
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27. Method 3: Ecosystem model estimation
Climate change
+ Rising CO2
Only Climate change
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28. Updated ecosystem carbon balance by ecosystem models (in East Asia)
Different factors’ (climate, climate +CO2, nitrogen deposition,
land-use change, O3 pollution, agricultural management,
fire and biofuels) contributions to the carbon balance of terrestrial
ecosystems in East Asia.
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29. Comparison of C balance in different regions
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30. Spatial distribution of C balance in China
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31. Conclusions Offsets ≈ 28-37% of emissions over 1980-2000
Comprehensive estimate of Chinese ecosystems carbon budget
A carbon sink of 0.19 to 0.26 Pg C / yr
Offsets ≈ 28-37% of emissions over
Offsets ≈ 16-22% of emissions over
50% forest; up to 30% in shrublands
More than 65% of the sinks are distributed in southern China owing to regional climate change, reforestation and afforestatioin programmes active, and shrubland recovery.
Recent trends in agricultural practice also cause an increase in carbon sequestration.
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32. Thank you!
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