Transcript Article2, Stabilisation, Uncertainty: Firenze

UNFCCC Article 2 <=> Article 6,
A web-based climate model for global
dialogue
Stabilisation scenarios under Uncertainty
WCCC-2003 Москва
Ben Matthews
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Jean-Pascal van Ypersele
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Institut d’astronomie et de géophysique G. Lemaître,
Université catholique de Louvain, Louvain-la-Neuve,
Belgium
Web: www.climate.be (UCL-ASTR)
jcm.chooseclimate.org (interactive model)
JCM also developed with:
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DEA-CCAT Copenhagen, UNEP-GRID
Arendal, KUPjcm.chooseclimate.org
Bern
UN Framework Convention on Climate
Change
Ultimate objective (Article 2):
Such a level should be achieved
within a time frame sufficient
- to allow ecosystems to adapt
naturally to climate change,
- to ensure that food production is
not threatened and
- to enable economic development
to proceed in a sustainable manner.'
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(technologies, lifestyles,
policy instruments)
inverse calculation
'...stabilization of greenhouse gas
concentrations in the atmosphere at
a level that would prevent
dangerous anthropogenic
interference with the climate
system.
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Emissions pathways
(biogeochemical cycles)
Critical Levels
(global temperature
/ radiative forcing)
Critical Limits
(regional climate changes)
Key Vulnerabilities
(socioeconomic factors)
jcm.chooseclimate.org
Role-play on Article 2 with students
Louvain la Neuve, Belgium, Dec 2002, as if COP11, Moscow, Dec
2005
UNFCCC-style-process,17 teams of National + NGO delegates.
Quantitative interpretation of Article 2:
●
Temperature rise (<1.9°C 2100-1990)
+ Sea-level rise (46cm 2100-1990)
•Principles for Adaptation funds :
Tax on emissions trading / JI (/CDM?)
+ Percapita emissions & GDP formula
Final compromise between Russia and Tuvalu (after US quit)
●
•Equity implications were key aspect of discussion
•Scientific inconsistency maybe realistic in policy compromises?
•Delegates used Java Climate Model to explore options / uncertainties.
By selecting parameters / indicators, same model can "justify" diverse
positions!
•Such "games" also help us to identify scientific issues.
Reconciling multi-criteria climate targets, Conversion to CO2 "equivalents"
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European Union 2 °C limit:
EU Council Of Ministers 1996:
"...the Council believes that global average temperatures
should not exceed 2 degrees Celsius above pre-industrial
level and that therefore concentration levels lower than 550
ppm CO2 should guide global limitation and reduction
efforts."
"This means that the concentrations of all GHGs should also be
stabilised. This is likely to require a reduction of emissions of
GHGs other than CO2, in particular CH4 and N2O"
However, widely varying interpretations of implications for emissions!
Why? Java Climate Model may help to investigate...
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Stabilisation scenarios in Java Climate
Model
(Article 2: critical limits => critical levels => emissions pathways)
Inverse calculation to stabilise
●
CO2 concentration (as IPCC "S"/ WRE scenarios)
●
Radiative Forcing (all-gases, "CO2 equivalent")
●
Global Temperature (e.g. to stay below 2C limit)
●
(Sea-level -difficult due to inertia in ocean / ice)
JCM Core science very similar to IPCC-TAR models, but
(unlike TAR SYR) includes mitigation of all greenhouse gases
and aerosols.
Iterative method to find concentrations attaining specified
forcing/temperature. Very fast response.
● Explore interactively by dragging target curve with mouse.
● Or systematically [email protected]
calculate probabilistic
analysis ...
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jcm.chooseclimate.org
Carbon Cycle
Other gases/Aerosols
Climate Model
Shifting the Burden of Uncertainty
On average, all sets of scenarios stabilise at the same
temperature level of 2°C above preindustrial level.
But their uncertainty ranges are very different!
(note picture in abstract book)
A Temperature limit rather than a Concentration
limit reduces the uncertainty for Impacts/
Adaptation...
(assuming we commit to adjust emissions to stay below
the limit, as the science evolves)
...however this increases the uncertainty
regarding emissions Mitigation pathways.
Which is better?
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81 Carbon cycle variants
3* Land-use-change emissions (Houghton, scaled),
3* CO2 fertilisation of photosynthesis ("beta"),
3* Temperature-soil respiration feedback ("q10"),
3* Ocean mixing rate (eddy diffusivity of Bern-Hilda model)
6 Ratios of emissions of different gases
Emissions of all gases (including CH4, N2O, HFCs, Aerosol and
Ozone precursors) reduced by same proportion as CO2 with respect
to one of six SRES baseline scenarios
note: atmospheric chemistry feedbacks included, but not varied
84 Forcing/Climate Model variants
3 * Solar variability radiative forcing
4* Sulphate aerosol radiative forcing
7* GCM parameterisations climate sensitivity, ocean mixing/upwelling,
surface fluxes (W-R UDEB model tuned as IPCC TAR appx 9.1)
note: for sea-level rise, should add uncertainty in Ice-melt parameters
Probability from fit to historical data
Relative probability of each set of parameters derived from
inverse of "error" (model - data)
 Measured global temperatures (CRU + proxies)
 Measured CO2 concentration (Mauna Loa + others)
Reject low-probability variants (kept 468 / 6804)
Ensures coherent combinations of parameters, e.g. :
 More sensitive climate models with higher sulphate forcing
 High historical landuse emissions with higher fertilisation
factor
Still 2808 curves per plot (including 6 SRES per set)
So show 10% cumulative frequency bands (using
probabilities)
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Carbon Cycle
Other gases/Aerosols
Climate Model
What CO2 level stabilises T<= 2°C ?
Range: 380 - 620ppm,
Mean ~ 475ppm, Median ~ 450ppm.
Over 90% of variants are below 550ppm
so a 550ppm target has a high risk of exceeding 2°C
If we want 90% of variants below 2C,
the concentration should not exceed 400ppm !
note: 550ppm "CO2 equivalent" (all gases) would bring us close to 2C.
However, to keep the temperature level, total radiative forcing (and
hence CO2 equivalent) must decline gradually. This is possible while
CO2 remains level, due to declining CH4 and O3 (short lifetime
gases).
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Article 2 needs global dialogue (Art 6)
Risk/Value Judgements (including equity implications):
Impacts: Key Vulnerabilities?
Acceptable level of
Change?
Risk:
Target Indicator?
Acceptable Level of
Certainty?
(choice of target indicator shifts the burden of uncertainty)
Such risk/value decisions cannot be made by scientific experts
alone.
The ultimate “integrated assessment model” remains the global
network of human heads.
To reach effective global agreements, we need an iterative global dialogue
including
citizens / stakeholders.
The correctivejcm.chooseclimate.org
feedback process is
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more important than the initial guess. So let's start this global debate!
Experiment with Java Climate
Model
Try JCM at jcm.chooseclimate.org
Works in web browser, Instantly responding graphics,
Based on IPCC-TAR methods / data, Open-source,
Labels in 10 languages, 50000 words documentation
JCM also used for teaching in several countries:
Univ Cath de Louvain (BE) Open University (UK),
Univ Bern (CH), Univ Washington (CA),...
Role-play "games" with students may be a useful way to experiment
wth the dialogue process and identify related scientific questions.
Longterm Vision: link such courses to make real global dialogue linking
students around the world. Please join in!
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jcm.chooseclimate.org