Quantify ecosystem carbon and water fluxes, and their consequences in terms of primary productivity and carbon storage, can now expand from beyond the local scale to regional, ecosystem and continental-scales
Shows range in climates
Shows range in climates
Currently, there is significant uncertainty about Australia’s net primary productivity - the difference between carbon that is taken up by vegetation from the atmosphere and carbon respired by plants and microbes. There is corresponding significant uncertainty about rates of water loss through transpiration from plants and evaporation from soil and water bodies. This obviously limits our understanding of and capacity to manage Australia’s interlinked carbon and water cycles.
Note that each obs. type has different space and time scales
Currently, there is significant uncertainty about Australia’s net primary productivity. There is corresponding significant uncertainty about rates of water loss through transpiration from plants and evaporation from soil and water bodies. This obviously limits our understanding of and capacity to manage Australia’s interlinked carbon and water cycles. Long-term continental Carbon balance (RHS) using BIOS2, constrained by data including OzFlux dataPrior parameters and their uncertainties lead to a continental NPP of 2.5±1.1 PgCyr−1, while the estimate constrained by all three data sets is2.1±0.4 GtCyr−1,->including eddy fluxes reduces uncertainty considerably (strongest effect). The impact of each of three data sets (leaf –NPP (litter-fall), streamflow and eddy flux data) and combinations thereof on the long-term mean Australian continental NPP estimate and its uncertainty. Each data set individually leads to a reduction in uncertainty compared with the prior estimate, although with quite different values, reflecting possible biases in the model and/or observations for the particular observable. The estimates are more convergent when 2 data sets are used simultaneously, and the estimate constrained by all three is a compromise between the results obtained using each data set individually.The error bars in Figure 3 indicate that eddy flux data provide a stronger constraint than leaf-NPP, even though leaf NPP observations more widely distributed (Figure 2). This reflects the high precision of the eddy flux measurements, compared with disparate litterfall observations which do not share a common methodology and are subject to large errors from fine scale heterogeneity. Long-term evaporation from streamflow provides a relatively weak constraint because in most regions of Australia, it is largely driven by rainfall (continentally, evaporation accounts for 90% of precipitation).
Verification – using allConstraints - Tumba, HS and Daly’s – see map at Slide 20
Long-term continental water balance (LHS) and Carbon balance (RHS) using BIOS2, constrained by data including OzFlux data
Here, the top two panes of the previous slide (NPP and ET) are shown with all elements greyed out. Superimposed in colour on the NPP pane are the various Roxburgh results. Superimposed on the ET pane are most of the WIRADA ET estimates. The old CABLE results from WIRADA will be removed for publication. Also left out of the WIRADA results are those of Yongqiang, which have some problems. All ET results are for the period Jan 2000-Dec 2005, except etlook which is for 2002/07-2005/06.
Net primary production is slightly larger (uptake) than heterotrophic respiration, largely because of the CO2 fertilisation effect. This leads to a small positive net ecosystem production (uptake), which is negated by fire and land use change emissions to give a small net biome production that is an emission. The interannual variability of net biome production is driven largely by variation in net ecosystem production due to moisture availability. This interannual variability is significantly larger than the entire greenhouse gas emissions (in GT C(eq) y-1).NBP = 0.056 Pg C year – emission; interannual variability about 0.4 Pg C, cf 0.15 CO2 emissionsNEP (NEE) Uptake about 0.1; cf 0.15 for anthropogenicTotal land atmopshere exchange for Australia is 0.15 + 0.0506 = 0.205 Pg C year.
Helen Cleugh_Near-real-time measurement of carbon dioxide, water and energy fluxes: determining the best available estimates of ecosystem carbon and water fluxes at continental scales
Near-real-time measurement of CO2, water and energy fluxes: Determining the bestavailable estimates of continental carbon and water fluxesHelen Cleugh, Eva van Gorsel and Vanessa Haverd CSIRO Marine and Atmospheric Research
Some climate policy questions andthe research needed to provide theanswersWhat is the role of natural land and ocean sinks insequestering greenhouse gas (GHG) emissions and what willhappen to these sinks in the future?• Carbon cycle observations that track the uptake and release of greenhouse gases in land, air and oceans• How does climate change and variability affect Australia’s carbon budget (sources and sinks; anthropogenic and biogenic)?• Climate models (such as ACCESS) include coupled carbon and water cycle
Some climate policy questions andthe research needed to provide theanswersHow can we use our natural land sinks to mitigate Australia’sGHG emissions?What is the impact of natural disturbance regimes; how arethey changing?• Investigate how climate and land management affect the stability of Australia’s land-based carbon sinks• How will carbon dioxide fertilisation affect Australian vegetation?• Ensuring global and regional climate simulations represent Australian terrestrial ecosystem processes
A capability to determine carbon and waterbudgets at ecosystem to continental scales• Uptake and release of CO2 and other GHG [fluxes]• Carbon stocks in soil, plants and air [stores]• Water and carbon• Measurements and models…. the TERN infrastructure “ecosystem”
AusPlots and OzFlux Australian Network Supersites Network Site characteristics CO2 and H2O Fluxes Biomass Radiation Soil carbon & nutrients Meteorology Leaf-level photosynthesis AusCover eMAST Data assimilation and Vegetation type integration into GPPVeg indices (NDVI, EVI) Knowledge of modelling applications Leaf area index ecosystem exchange Fire of carbon, water & Canopy properties ..... energy …. the TERN infrastructure “ecosystem”
OzFlux: a continental network of flux stations to measure ecosystem fluxes using nationally-consistent approachesFlux towers measuring vineyardand forest CO2 and water H fluxes ET Q • CO2 (NEE) and water use (ET) • Energy: Radiation (Q) and heat (H, G) Q NEE • Spatially-averaged at canopy-scale • Continuous: hourly to multi-annual G
OzFlux: carbon and water fluxes available via a data portal for a range of Australian climates and ecosystemsSee OzFlux DataPortal demo. byPeter Isaac thisafternoon
What is Australia’s net carbon balance? • How does climate change and variability affect Australia’s carbon budget (sources and sinks; anthropogenic and biogenic)? • How much water is required for an ecosystem to sequester CO2?
Determining Australia’s net biogenic carbon & waterbalance by combining models and observations • Haverd et al (2012) Using multiple observation types to reduce uncertainty in Australia’s terrestrial carbon and water cycles, Biogeosciences Discuss., 9 (2012) • BIOS2 modelling environment • Multiple observations
BIOS2 Model Environment (Haverd et al, 2012) BIOS2 = CABLE-SLI-CASAcnp in AWAP operational frameworkCABLE = Community SLI = Soil-Litter-Iso CASAcnp =Atmosphere-Biosphere-Land • Soil hydrology, evaporation Biogeochemical modelExchange model • Soil & plant C, N, P Haverd et al. (2011)• Water, energy, carbon fluxes dynamicsWang et al. (2011) Wang et al. (2007)AWAP = Australian Water Availability Project• Meteorology and soil data• Continental processing framework• Model-Data FusionRaupach et al. (2009)
Determining Australia’s net biogenic carbon & waterbalance by combining models and observations • Haverd et al (2012) • BIOS2 modelling environment = CABLE + CASAcnp + SLI • Multiple data sets: • OzFlux carbon, water and energy fluxes • Streamflow from gauged catchments • Litterfall (leaf NPP) • Carbon pools (above ground biomass, soil carbon)
Including OzFlux data to constrain BIOS2 simulations of NPP (Net Primary Production) for Australian continent Prior estimate Eddy fluxes Streamflow Litterfall Eddy fluxes + Litterfall error bars = uncertainty Streamflow + Litterfall from propagated parameter Streamflow + Eddy fluxes uncertainties (1 std. dev.)Eddy fluxes + Litterfall + Streamflow 0 1 2 3 4 Net Primary Production (NPP) =y2.1 GT carbon per year NPP (GtC ) -1 Including OzFlux flux data yields the greatest reduction in uncertainty in NPP and ET
A reality check - comparing OzFlux measured GPP and BIOS2 simulationsOzFlux = ensembleannual cycleBIOS2 = long-termmean annual cycle
A reality check - comparing OzFlux measured ET and BIOS2 simulationsOzFlux = ensembleannual cycleBIOS2 = long-termmean annual cycle
A reality check - comparing OzFlux measured ET and BIOS2 simulationsMonthly AnnualMonthly Annual
Australia’s water and carbon balance from BIOS2, constrained by data Soil Evaporation• Energy, carbon, water budgets• 1990 – 2009 (monthly)• 5 km resolution• Using BIOS2 (CABLE + SLI + CASAcnp) Total NPP Transpiration
NPP (g m-2 d-1) 3pg 3 i AussieGrass BiosEquil Century 2 CenW dLdP Miami-oz12 mean NPP estimates 1 Miami Olsonfor Australia RFBN TMS(Roxburgh et al 2004) 0 Vast ET (mm y-1) ii AWAP7 mean ET estimates for 1000 AWRA GuerschmanAustralia NDTI etlook(King et al 2012) MODIS 500 0 Australia Savanna Tropics Warm Temp Cool Temp Mediterr Desert 1 2 3 4 5 6 A
Concluding Comments (1)• Climate mitigation and adaptation policy drivers requires a capability to determine carbon and water budgets at ecosystem to continental scales – TERN provides model – data research infrastructure needed – OzFlux + AusCover + Supersites + AusPlots + Soils• OzFlux data have been used to: – Test and improve the land surface model [CABLE] for Australian ecosystems. – CABLE is part of Australia’s newly developed global climate model [ACCESS] – Significantly reduce the uncertainty in estimated NPP for Australia, using CABLE as part of BIOS2
Concluding Comments (2)• Insights into the dynamic carbon and water budgets for the Australian continent, e.g.: – Large inter-annual variability in NPP driven by variation in available moisture – And larger than anthropogenic greenhouse gas emissions