Download Scientific and policy requirements for

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