Download Modelling the global marine carbon cycle

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Modelling the global marine carbon cycle
'end-to-end'
Christoph Heinze
University of Bergen, Norway
Geophysical Institute & Bjerknes Centre for Climate Research
Uni-Research Bjerknes AS
Outline:
1 Some principles about marine carbon cycling
2 The oceanic anthropogenic-carbon uptake problem is a kinetic problem
3 Models of global ocean biogeochemistry
4 Some recent findings…
This is a truncated version of the presenation as given at Brussels on
Oct. 4.
A more complete version of the talk can be requested for private use
from:
[email protected]
1 Some principles about marine carbon cycling
The ocean is a large carbon reservoir. Small changes in it can induce
considerable variations in the atmospheric CO2 content.
In the ocean CO2 is highly reactive due to the ability of seawater to disscociate
weak acids:
1. Dissociation step:
CO2 + H2O
HCO3- + H+
2. Dissociation step:
CO32- + H+
Sea water – buffer system!
CO2 + H2O + CO32-
(1+x)HCO3- + (1-x)CO32- + (1-x)H+
HCO3-
CO2 : HCO3- : CO321:
100 :
10
“ocean levers” to change atmospheric CO2:
IPCC AR4, ch. 7, after Heinze et al. (1991)
Major difficulty:
The pristine inorganic carbon system in the ocean has not been measured.
“Anthropogenic carbon” (the excess over the natural carbon) has to be
reconstructed from present day observations using transfer functions and
assumptions.
We can illustrate this problem in a model framework, where the “preindustrial” carbon system is known.
TCO2 from a model (HAMOOC4)
Pre-industrial 1751
Atlantic Ocean
Today 2004
TCO2 from a model (HAMOOC4)
Pre-industrial 1751
Pacific Ocean
Today 2004
TCO2 from a model (HAMOOC4)
Pre-industrial 1990
Atlantic Ocean
Today 2004
TCO2 from a model (HAMOOC4)
Pre-industrial 1990
Pacific Ocean
Today 2004
2 The oceanic anthropogenic-carbon uptake problem is a kinetic problem
The ocean has the potential to take up large amounts of human produced
CO2 but needs time for this.
What about biology?
3 Models of global ocean biogeochemistry
Ocean models are a key tool for understanding and predicting natural
and human induced changes of the carbon cycle.
Atlantic
Pacific
Model
HAMOCC2s
Observations
GEOSECS
HAMOCC2s model
BSi
(opal)
CaCO3
org. C
clay
avg. sediment (model)
Atl
Pac
[CO32-] (model)
Heinze, Hamocc2 model
BOGCM with NPZD ecosystem model
An isopycnic ocean carbon cycle model
K. M. Assmann, M. Bentsen, J. Segschneider, and C. Heinze
Geosci. Model Dev., 3, 143-167, 2010
BOGCM with NPZD ecosystem model
An isopycnic ocean carbon cycle model
K. M. Assmann, M. Bentsen, J. Segschneider, and C. Heinze
Geosci. Model Dev., 3, 143-167, 2010
Norwegian Earth System Model
“old”
Will include
land use
changes
“new” NorESM
Tjiputra, Assmann, Bentsen, Bethke,
Otterå, Sturm, and Heinze, 2010, GMD
Will include
improved N cycle
& river loads
4 Some recent findings…
…past ocean, modern ocean, and future challenges
Test of parameter changes scaled with EPICA Dome C ice core ∆D signal
All parameter changes (low rain ratio,
no Redfield ratio change yet).
Example, fit currently underway:
= observation
pCO2
= model
Vostok ice core, Antarctica,
Barnola et al., 1987, Nature
Sediment Core: RC24-07
Verardo&McIntyre Paleoceanography 1994
Lat: -1.35 S Lon: -11.917 W
Bottom depth: 3899 m
Region: Central eq. Atlantic
CaCO3
vs.
age
vs.
depth
in
core
= observation
Paleo tracer
change
Time yr BP
Single sequential fits of model to observations,
time slice by time slice,
time series of maximum likelihood solutions for parameter changes
valid for each of the single time slices
= observation
Paleo tracer
change
Time yr BP
Single sequential fits of model to observations,
time slice by time slice,
time series of maximum likelihood solutions for parameter changes
valid for each of the single time slices
= observation
Paleo tracer
change
Continuous fit through entire climatic cycle,
Time yr BP
optimal T and pCO2 dependent parameters of
physical/chemical/biological functional relationship between C cycle
(ocean acidification and others) and climate change;
less free parameters and system has higher chance to become
overdetermined
= observation
Paleo tracer
change
one sweep, no sequential time slice consideration
Continuous fit through entire climatic cycle,
Time yr BP
optimal T and pCO2 dependent parameters of
physical/chemical/biological functional relationship between C cycle
(ocean acidification and others) and climate change;
less free parameters and system has higher chance to become
overdetermined
Ocean internal carbon re-distribution
Atmospheric
CO2
Upper
ocean
CO2
intermediate w.
CO2
Deep
ocean
CO2
Eemian
130 kyrBP
Last glacial
maximum
20 kyrBP
Preindustrial
1750
Low
CO2
High
Ocean internal carbon re-distribution
Large external carbon input into ocean
Atmospheric
CO2
Upper
ocean
CO2
intermediate w.
CO2
Deep
ocean
CO2
Eemian
130 kyrBP
Last glacial
maximum
20 kyrBP
Preindustrial
1750
Today
Low
CO2
High
Ocean internal carbon re-distribution
Large external carbon input into ocean
Atmospheric
CO2
Upper
ocean
CO2
intermediate w.
CO2
Deep
ocean
CO2
Eemian
130 kyrBP
Last glacial
maximum
20 kyrBP
Preindustrial
1750
Today
Year 20502150
Low
CO2
High
3-D is important for air-sea CO2 fluxes !!!
Southern Ocean key in anthropogenic
CO2 uptake in future
Study with Bergen Climate Model
(predecessor of NorESM model)
Ocean: MICOM (isopycnic) & HAMOCC
Uptake
Storage
Anthropogenic carbon dynamics in the changing
ocean
J. F. Tjiputra, K. Assmann, and C. Heinze
Ocean Sci., 6, 605-614, 2010
= meridional transport into region
= uptake form atmosphere
Anthropogenic carbon dynamics in the changing
ocean
J. F. Tjiputra, K. Assmann, and C. Heinze
Ocean Sci., 6, 605-614, 2010
C cycle
perturbation
amplitude
1. Climate Earth system models must
reproduce natural system changes and
should be calibrated through the paleoclimate record.
C cycle
perturbation
time scale
Last glacial cycle, Holocene
Anthropocene 1750 - ?
C cycle
perturbation
amplitude
1. Climate Earth system models must
reproduce natural system changes and
should be calibrated through the paleoclimate record.
C cycle
perturbation
time scale
Last glacial cycle, Holocene
2. The
“glacial”
parameter
calibration will
help to
improve the
model skill for
long-term and
low amplitude
changes.
Anthropocene 1750 - ?
3. In addition for predicting strong short-term
changes are required:
C cycle
perturbation
amplitude
(a) Process understanding (qualitative,
quantitative)
(b) Sustained long-term observations including
legacy data sets from NOW.
(c) Efficient high resolution Earth system models.
(d) Optimisation of coupled models.
(e) Development of early warning indicators.
1. Climate Earth system models must
reproduce natural system changes and
should be calibrated through the paleoclimate record.
C cycle
perturbation
time scale
Last glacial cycle, Holocene
2. The
“glacial”
parameter
calibration will
help to
improve the
model skill for
long-term and
low amplitude
changes.
Anthropocene 1750 - ?
CHANGING CLIMATE
International coordination, GEO, GEOSS, GMES
Guard rails for
policies,
mitigation
FP6
CARBOOCEAN integrated project
Core Theme 2 - Observing systems
(Towards ICOS)
Core Theme 1 - Key processes,
feedbacks, future scenarios, vulnerabilities
Global and regional synthesis and
synergies with international projects
Core Theme 3 - Data model integration
IPCC
assessments
5 and 6
ICOS
global &
regional
monitoring &
prediction
systems
FP8
Emerging
knowledge
gaps to be
closed
Securing our
sustainable
future
Projects on ocean acidification, impacts, ecosystems