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Scientific and policy requirements for comprehensive and dynamic carbon budgets Why regional carbon budgets? Scientific and Policy Background Mike Apps GCP Scientific Steering Committee & Natural Resources Canada Canadian Forest Service MJ Apps, Canadian Forest Service Nov 2004 Two Overarching Questions How will rates of atmospheric C accumulation change? – Impacts – Adaptation measures Can the fluxes causing the atmospheric accumulation be controlled? – Mitigation: what can be done to reduce sources and or increase sinks – Can these be monitored effectively? – How long will they last? MJ Apps, Canadian Forest Service Nov 2004 Active Carbon Cycle Exchange of 120 GtC/yr (land), and 90 GtC/yr (ocean) C is cycled, not permanently stored A natural cycle that has operated for at least 4 glacial cycles Provocative insight: Kleidon Climatic Change 2004 MJ Apps, Canadian Forest Service Nov 2004 Variation in T and CO2 over last 4 glacial cycles Today Future? CO2 A stable mode of behaviour for at least the past ½ million years Temperature Falkowski et al., 2000 MJ Apps, Canadian Forest Service Nov 2004 Petit et al., 1999 Perturbed PerturbedActive ActiveCarbon CarbonCycle Cycle Human activity alters mechanisms of the cycle Fossil deposits How the Earth system handles these perturbations will determine the impacts How human activities are modified will influence the magnitude and timing of the perturbation MJ Apps, Canadian Forest Service Nov 2004 And adds additional carbon to the active cycle Global Budget: Top Down Perspective Data for 1990s from Houghton 2003 Re-analyses of Ocean (Plattner) and LUC data Atmospheric accumulation rate 3.2 GtC per year 1990s Atmosphere Surface biosphere 6.3 2.2 F Fuel, Land-Use Cement Change 6 GtC/yr - equivalent to burning all of Canada’s trees every two years. MJ Apps, Canadian Forest Service Nov 2004 2.9 Land Uptake Net: 0.7 1990s 2.4 Ocean Uptake Global Budget: Main questions Atmospheric accumulation rate 3.2 GtC per year 1990s Atmosphere Surface biosphere 6.3 2.2 F Fuel, Land-Use Cement Change 2.9 Land Uptake 2.4 Ocean Uptake How good are estimates? Where are the release occurring? How will they change over time? Can human behavior be modified? MJ Apps, Canadian Forest Service Nov 2004 Global Budget: Main questions Atmospheric accumulation rate 3.2 GtC per year 1990s Atmosphere Surface biosphere 6.3 2.2 F Fuel, Land-Use Cement Change 2.9 Land Uptake 2.4 Ocean Uptake Similar set of questions MJ Apps, Canadian Forest Service Nov 2004 Global Budget: Main questions Atmospheric accumulation rate 3.2 GtC per year 1990s Atmosphere Surface biosphere 6.3 2.2 F Fuel, Land-Use Cement Change 2.9 Land Uptake 2.4 Ocean Uptake What are the mechanism responsible? Where is the uptake occurring? How will it change over time? Can management influence? MJ Apps, Canadian Forest Service Nov 2004 Global Budget: Scoping mitigation opportunities Atmospheric accumulation rate 3.2 GtC per year 1990s Atmosphere Surface biosphere 6.3 2.2 F Fuel, Land-Use Cement Change 2.9 Land Uptake 2.4 Ocean Uptake Comprehensive Activities are REGIONAL undertaken budgets within REDUCE SOURCES INCREASE SINKS are regions needed at for localguidance levels MJ Apps, Canadian Forest Service Nov 2004 carried outC at local to regional scales Mitigation: Regional Budget requirements: • Comprehensive/sectoral perspective – Implementation and accuracy • Spatially complete – Resolution appropriate for decision making or reporting • Appropriate time scales – Resolution years, horizon 10-100 yrs • Forecasting/scenario ability – Planning strategies • Tracking/monitoring ability with uncertainties – Evaluating, assessing, and adaptive management. Reporting • Transparency, credibility, explicit uncertainty – Accountability and comparability MJ Apps, Canadian Forest Service Nov 2004 Global Perspective: reconciling top-down and bottom up Land uptake currently inferred as residual. – Bottom up estimates are incomplete – limited by sectors, regions, and data Houghton reviewed the recent top down and bottom up estimates and attempts to reconcile. Houghton concludes – global land net uptake : net tropical source and a net northern sink, – magnitudes depend on accuracy of estimates of tropical LUC and – Both net tropical source and net northern sink appear to change R.A.Houghton, 2003. over time Global Change Biology 9: 500-509, MJ Apps, Canadian Forest Service Nov 2004 Importance of mechanisms for land uptake What we now know: • No single region is responsible • No single mechanism is responsible Rather • Spatial mosaic of sources and sinks – at many scales, across landscapes, across biomes, across regions • Biological sources and sinks are often autocorrelated (but with time delays) • The spatial mosaic changes with time Gaining a quantitative understanding of the processes underlying the land uptake is INTRINSICALLY a REGIONAL AND LOCAL problem, with scaling up challenges REGIONAL CARBON BUDGETS MJ Apps, Canadian Forest Service Nov 2004 Importance of mechanisms for land uptake 1) Different mechanisms different mitigation approaches policy interest, scientific challenge 2) Different mechanisms different future trajectories (climate implications) scientific challenge, policy need – though not always appreciated! 3) Ability to factor out direct human interventions from indirect responses and natural variability policy request, strong scientific challenge MJ Apps, Canadian Forest Service Nov 2004 Two broad mechanisms for land uptake Changes in productivity (stimulated NPP, reduced respiration) in response to CO2, climate, nutrient, management … Examples •Disturbed soils •Forest Stand Site Ci 1. Biomass+ detritus +soils age Different factors important for different regions MJ Apps, Canadian Forest Service Nov 2004 Increased Site fertility (Carrying capacity) Increased growth rate, decreased decomposition Deceased site fertility, growth rate, … Two broad mechanisms for land uptake 2. Changes in demographics (age distribution) due to change in mortality (LUC or natural distrubances) • At landscape or regional scale, must take into account age distribution • Shift of average age to right increases C (i.e., landscape becomes a sink) • Shift to left decreases C (i.e. source) MJ Apps, Canadian Forest Service Nov 2004 Site level Ci stand age Subtle scaling issue: Site to Landscape But, significant time Must be very careful before C released when scaling up site to during/after disturbance regional is recaptured stand Ci Site scale accumulation Biomass+ detritus +soils stand age Local Tower Source Sink Contribution Net loss Net removal to landscape remains deficit for much longer than instantaneous measurement suggests MJ Apps, Canadian Forest Service Nov 2004 Need for comprehensive system perspective At any scale, net flux to atmosphere is a complex balance of many individual time varying fluxes each having different controls Two basic approaches to carbon balance: 1) Flux estimates 2) Pool (stock) change CO2 PEAT STAND LEVEL TOPS CH4 LITTER STEM DEBRIS PRODUCTS ROOTS Soil Equivalent/complementary results (conservation of mass) IFF all significant fluxes, and all significant stock changes are accounted MJ Apps, Canadian Forest Service Nov 2004 Carbon Carbon balance balance at at a regional global scale scale scale an ecosystem e.g., Barford et al (2001)(Harvard ) e.g., Janssens e.g., Houghton et al (2004) (2003)(Europe) Need for comprehensive system perspective Especially important in predicting future atmospheric carbon if some of the present feedbacks fail … 3.2>8Gt/yr? ± 0.1 GtC/yr Atmosphere increase Atmosphere Balance will be altered by global change Ocean Forests Surface biosphere ? Circulation ? •Sarmiento et al 1998 •Cox et al 2000 •Peterson et al 2001 •Kurz &Apps 1999 2.4 ± 0.7 6.3 ± 0.4 2.2 ±0.8 2.9 ± 1.1 F Fuel, Cement MJ Apps, Canadian Forest Service Nov 2004 Land-Use Land Change uptake Oceans Betts: Future changes (?) global & region scale • Carbon feedbacks from dieback in Amazon Ignoring climate change Including climate change Regional changes with global significance Betts et al 2004 MJ Apps, Canadian Forest Service Nov 2004 Uptake Release Kurz and Apps: Contemporary, regional scale Stand replacing disturbances in Canadian forests have changed over last 50 years With large C consequences Note Change after 1970 Kurz and Apps, Ecol. Appl. 1999 MJA IOS Mar 2004 23 MJ Apps, Canadian Forest Service Nov 2004 Summary: Policy issues and challenges Policy and decision makers focus on: – Likely impacts (party/country level and globally) • Of not doing anything (impacts and adaptation potential) • Of mitigation measures (cost/benefit) • Timing of these impacts – Feasible mitigation opportunities • Within country • Globally – Robust analysis of party (country) level budgets • Trade and negotiations • Planning and monitoring MJ Apps, Canadian Forest Service Nov 2004 Summary: Science issues and challenges Quantitative understanding the spatial and temporal dynamics of the perturbed carbon cycle: – Reconciling top-down and bottom-up estimates of the global carbon budget – Understanding the mechanisms that control the major fluxes (anthropogenic and biospheric) making up the budget – Predicting how the budget will change over time – Observation and measurement challenges posed by the above needs MJ Apps, Canadian Forest Service Nov 2004 The way forward? ‘Better’ regional carbon budgets • Data, comprehensive (processes, sectors, pools), spatial representation, dynamic that can be used • to constrain and augment global budgets • to inform decision makers at regional scales • to enable implementation of carbon management strategies • to monitor progress at relevant scales and facilitate adaptive management MJ Apps, Canadian Forest Service Nov 2004 Think globally, analyze locally MJ Apps, Canadian Forest Service Nov 2004