mj apps, canadian forest service nov 2004 why regional carbon budgets? scientific and policy...

MJ Apps, Canadian Forest Service Nov 2004

Why regional carbon budgets?Scientific and Policy Background

Scientific and policy requirements for comprehensive and dynamic carbon budgets

Mike Apps GCP Scientific Steering Committee

& Natural Resources CanadaCanadian Forest Service


How will rates of atmospheric C accumulation change?

– Impacts– Adaptation measures

Can the fluxes causing theatmospheric 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?

Two Overarching Questions


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


Variation in T and CO2 over last 4 glacial cycles

A stable mode of behaviour for at least the past ½ million years

Temperature

CO

2

Future?

Today

Falkowski et al., 2000

Petit et al., 1999


Perturbed Active Carbon CyclePerturbed Active Carbon Cycle

Fossil deposits

And adds additional carbon to the active cycle

Human activity alters mechanisms of the cycle

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


2.4OceanUptak

e

Land Uptake

2.2Land-UseChange

6.3 F

Fuel, Cemen

t

Global Budget: Top Down Perspective

Atmosphere

Surface biosphere

Data for 1990sfrom Houghton 2003Re-analyses of Ocean (Plattner) and LUC data

Net: 0.7 1990s

Atmospheric accumulation rate3.2 GtC per year 1990s

2.9

6 GtC/yr - equivalent to burning all of Canada’s trees every two years.


2.4OceanUptak

e

Land Uptake

2.2Land-UseChange

6.3 F

Fuel, Cemen

t

Global Budget: Main questions

Atmosphere

Surface biosphere


2.9

How good are estimates?Where are the release occurring?

How will they change over time?Can human behavior be modified?


Similar set of questions

2.4OceanUptak

e

Land Uptake

2.2Land-UseChange

6.3 F

Fuel, Cemen

t


Atmosphere

Surface biosphere


2.9


2.4OceanUptak

e

Land Uptake

2.2Land-UseChange

6.3 F

Fuel, Cemen

t


Atmosphere

Surface biosphere


2.9

What are the mechanism responsible?Where is the uptake occurring?

How will it change over time?Can management influence?


REDUCE SOURCES INCREASE SINKS

Global Budget: Scoping mitigation opportunities

2.4OceanUptak

e

Land Uptake

2.2Land-UseChange

6.3 F

Fuel, Cemen

t

Atmosphere

Surface biosphere


2.9

Activities are undertaken within regions at local levelsComprehensive REGIONAL

budgets are needed for guidance


Mitigation: carried out at local to regional scalesMitigation: Regional C 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


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

over time

R.A.Houghton, 2003.Global Change Biology 9: 500-509,


Importance of mechanisms for land uptakeWhat we now know:• No single region is responsible• No single mechanism is responsibleRather • 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


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


Increased growth rate, decreased decomposition

Different factors important for different regions

Increased Site fertility(Carrying capacity)

Two broad mechanisms for land uptake

1. Changes in productivity (stimulated NPP, reduced respiration) in response to CO2, climate, nutrient, management …

Examples

•Disturbed soils•Forest Stand

Biomass+ detritus +soils

age

Sit

e C

i

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)

stand age

Ci

Site level• 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)


stand age

stan

d C

i

Biomass+ detritus +soils

Source Sink

Subtle scaling issue: Site to Landscape

Local Tower

But, significant time before C released during/after disturbance is recaptured

Net loss Net removal

Site scale accumulation

Must be very careful when scaling up site to

regional

Contribution to landscape

remains deficit for much longer than instantaneous measurement suggests


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

Equivalent/complementary results (conservation of mass) IFF all significant fluxes, and all significant stock changes are accounted

Two basic approaches to carbon balance:

1) Flux estimates

2) Pool (stock) change

STAND LEVELCH4CO2

TOPS

STEMLITTER DEBRIS

PRODUCTS

ROOTS

Soil

PEAT

STAND LEVELCH4CH4CO2CO2

TOPS

STEMLITTER DEBRISLITTER DEBRIS

PRODUCTSPRODUCTS

ROOTS

Soil

ROOTSROOTSROOTSROOTS

Soil

PEATPEAT

Carbon balance at an ecosystem scalee.g., Barford et al (2001)(Harvard )

Carbon balance at a regional scale

e.g., Janssens et al (2004) (Europe)

Carbon balance at a global scale

e.g., Houghton (2003)


2.9 ± 1.1 Land uptake

2.4 ± 0.7 Oceans

3.2 ± 0.1 GtC/yrAtmosphere increase

6.3 ± 0.4F Fuel,Cement

Atmosphere

Surface biosphere

2.2 ±0.8Land-UseChange

Forests

?

Ocean Circulation

?

•Sarmiento et al 1998•Peterson et al 2001

>8Gt/yr?

Need for comprehensive system perspective

Especially important in predicting future atmospheric carbon if some of the present feedbacks fail …

Balance will be altered by global change

•Cox et al 2000•Kurz &Apps 1999


• Carbon feedbacks from dieback in Amazon

Ignoring climate change

UptakeIncluding climate change

Release

Betts: Future changes (?) global & region scale

Regional changes with global significance

Betts et al 2004

MJ Apps, Canadian Forest Service Nov 2004 MJA IOS Mar 2004 23

Kurz and Apps, Ecol. Appl. 1999

With large C consequences

Note Change after 1970

Kurz and Apps: Contemporary, regional scale

Stand replacing disturbances in Canadian forests have changed over last 50 years


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

Summary: Policy 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

Summary: Science issues and challenges


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


Think globally, analyze locally

mj apps, canadian forest service nov 2004 why regional carbon budgets? scientific and policy...

Documents

f fuel

gtcyr land

oceanuptakeland uptake2

year 1990s2

global land net uptake

perturbationglobal budget

regional c budget requirements

regional carbon budgets