Global Climate Model (GCM) Scenarios forGlobal Climate Model (GCM) Scenarios forClimate Change Impacts Research Climate Change Impacts Research

Trevor Murdock, M.Sc. Trevor Murdock, M.Sc. tmurdocktmurdock@@uvicuvic.ca.ca

Canadian Institute for Climate Studies Canadian Institute for Climate Studies www.cics.uvic.cawww.cics.uvic.ca

14 Sep 200414 Sep 2004

OutlineOutline

1.1. Context & definitionsContext & definitions

2.2. Global Climate Models (GCMs) Global Climate Models (GCMs) • ScenariosScenarios• UncertaintyUncertainty• EmissionsEmissions• VegetationVegetation

3.3. Applying scenarios to impacts studiesApplying scenarios to impacts studies• Downscaling: RCMs & other approachesDownscaling: RCMs & other approaches• Climate normalsClimate normals

4.4. Scenarios for BCScenarios for BC

5.5. SummarySummary

Context and definitionsContext and definitions• Identify Identify VulnerabilitiesVulnerabilities - - what aspects of what aspects of

climate change is a community / region climate change is a community / region susceptible to?susceptible to?

• Study potential Study potential ImpactsImpacts of climate of climate change; projections of future climate are change; projections of future climate are required; use a range of required; use a range of ScenariosScenarios from from Global Climate Models (Global Climate Models (GCMsGCMs) to deal ) to deal with uncertaintywith uncertainty

• AdaptationAdaptation strategies involve managing strategies involve managing for current and potential future climate for current and potential future climate (change and variability) impacts(change and variability) impacts

What are Global Climate Models?What are Global Climate Models?• GCMs compute global weather

patterns several times per day

projected over the next century

• GCMs are the“…only credible tools currently

available for simulating the

physical processes that determine

global climate...” [IPCC]

Sources of UncertaintySources of Uncertainty

[Source: Hadley Centre for Climate Prediction and Research, UK Met. Office]

Emissions ScenariosEmissions Scenarios– Emissions scenarios Emissions scenarios

based on different based on different assumptions aboutassumptions abouthow the globalhow the globaleconomy will economy will evolve and emitevolve and emitfossil fuels overfossil fuels overthe next centurythe next century

– SRES recommendedSRES recommended

– IS92a gg & ga also availableIS92a gg & ga also available

– Naming convention also denotes members of Naming convention also denotes members of ensembles with numbers and ensemble averages ensembles with numbers and ensemble averages with x (i.e. CGCM2 A11, A12, A13, A1x)with x (i.e. CGCM2 A11, A12, A13, A1x)

Emissions & ConcentrationsEmissions & Concentrations

GCMsGCMs

Each GCM has different parameterizations of physics of the Atmosphere, Ocean, Cryosphere & Biosphere

CGCM1CGCM1 Canadian Centre for Climate Modelling and Analysis Global Coupled Canadian Centre for Climate Modelling and Analysis Global Coupled Model 1Model 1

CGCM2CGCM2 Canadian Centre for Climate Modelling and Analysis Global Coupled Canadian Centre for Climate Modelling and Analysis Global Coupled Model 2Model 2

HadCM2HadCM2 Hadley Centre Coupled Model 2Hadley Centre Coupled Model 2

HadCM3HadCM3 Hadley Centre Coupled Model 3Hadley Centre Coupled Model 3

GFDLR15GFDLR15 Geophysical Fluid Dynamics Laboratory R15Geophysical Fluid Dynamics Laboratory R15

GFDLR30GFDLR30 Geophysical Fluid Dynamics Laboratory R30Geophysical Fluid Dynamics Laboratory R30

ECHAM4ECHAM4 European Centre/Hamburg Model 4European Centre/Hamburg Model 4

CSIROMk2CSIROMk2bb

Commonwealth Scientific Industrial Research Organization Mk2bCommonwealth Scientific Industrial Research Organization Mk2b

CCSRNIESCCSRNIES Center for Climate Research - National Institute for Environmental Center for Climate Research - National Institute for Environmental StudiesStudies

NCARPCMNCARPCM National Center for Atmospheric ResearchNational Center for Atmospheric Research

Vegetation in GCMsVegetation in GCMs

• GCMs typically ignore climate/vegetation GCMs typically ignore climate/vegetation feedbacks:feedbacks:

• CCCMa (Canada)CCCMa (Canada)– CGCM2 - no vegetationCGCM2 - no vegetation– CGCM3 - simple CLASS schemeCGCM3 - simple CLASS scheme– CGCM4 - will include more sophisticated vegetation CGCM4 - will include more sophisticated vegetation

and biophysical processesand biophysical processes

• Hadley Center (UK) Hadley Center (UK) – HadCM3 includes representation of freezing and HadCM3 includes representation of freezing and

melting of soil moisture and evaporation includes melting of soil moisture and evaporation includes the stomatal resistance on temperature, vapour the stomatal resistance on temperature, vapour pressure, and COpressure, and CO22 concentration (Cox et al., 1998) concentration (Cox et al., 1998)

Applying Scenarios: DownscalingApplying Scenarios: Downscaling

• GCM scenarios coarse resolution (100s of kms / monthly)

• Dynamic methods • retain internal physical consistency• high resolution AGCMs, Regional Climate Models (RCMs)

• Statistical methods • less costly/less complicated• Weather generators – LARS-WG, Multiple linear regression

- SDSM

• Best solution often not to downscale at all• interpolate (introduces false geographical precision)• apply change fields from larger spatial scale to working

scale

Regional Climate ModelsRegional Climate Models

1.Account for sub-grid scale forcings such as topography and land cover in a physically-based way

2.Note: more physics can mean more uncertainty

Applying Scenarios: Climate Applying Scenarios: Climate NormalsNormals

- “ “Baseline Climates” Baseline Climates” - Usually 1961-1990Usually 1961-1990- Good baseline data needed for 2 reasons:Good baseline data needed for 2 reasons:

- GCM scenario differences need to be applied to an GCM scenario differences need to be applied to an observed baseline (to remove model bias).observed baseline (to remove model bias).

- Impacts assessment should include analysis of recent Impacts assessment should include analysis of recent climateclimate

- Types of observational baselines:Types of observational baselines:- Individual station data (raw, homogenized)Individual station data (raw, homogenized)- Gridded station data (interpolated)Gridded station data (interpolated)- Gridded satellite dataGridded satellite data- Gridded reanalysis data (statistical/dynamical/modeling)Gridded reanalysis data (statistical/dynamical/modeling)- PRISM 4km x 4km ( or resampled to 2km x 2 km ) grid – PRISM 4km x 4km ( or resampled to 2km x 2 km ) grid –

Temperature, Rainfall, SnowfallTemperature, Rainfall, Snowfall

CCIS – Custom RegionsCCIS – Custom Regions

http://www.cics.uvic.ca/scenarios/data/select.cgihttp://www.cics.uvic.ca/scenarios/data/select.cgi

• Predefined regions or create by clicking on Predefined regions or create by clicking on mapmap

• Control panel interface (rather than steps)Control panel interface (rather than steps)

• Dynamic map creation allows for user Dynamic map creation allows for user customization of many features (legend, customization of many features (legend, decimal places, grid, etc.)decimal places, grid, etc.)

• Meta-information about full map and region Meta-information about full map and region (min, max, median, area-weighted mean, (min, max, median, area-weighted mean, stddev)stddev)

http://www.cics.uvic.ca/scenarios/data/select.cgihttp://www.cics.uvic.ca/scenarios/data/select.cgi

SummarySummary• Impacts work most effective in the context of Impacts work most effective in the context of

Vulnerability, Impacts, and AdaptationVulnerability, Impacts, and Adaptation

• GCM based scenarios used to represent range of GCM based scenarios used to represent range of plausible future climates for impacts studiesplausible future climates for impacts studies

• Vegetation beginning to be included explicitly in Vegetation beginning to be included explicitly in GCMsGCMs

• Downscaling may be used to overcome differences Downscaling may be used to overcome differences in scale between GCMs and impacts analysisin scale between GCMs and impacts analysis

• GCM change fields are applied to climate normalsGCM change fields are applied to climate normals

• Scenarios for BC – see Scenarios for BC – see www.cics.uvic.ca/scenarioswww.cics.uvic.ca/scenarios for more tools, scenarios, and datafor more tools, scenarios, and data