OUCE Oxford University Centre for the Environment “Applying probabilistic climate change information to strategic resource assessment and planning” Funded by ENVIRONMENT AGENCY TYNDALL CENTRE

OUCE Oxford University Centre for the Environment Overall Objective To develop a risk-based framework for handling probabilistic climate change information and for estimating uncertainties inherent to impact assessments performed by the Agency for strategic planning (water resources and biodiversity in the first instance).

OUCE Oxford University Centre for the Environment Specific Objectives  To develop and compare methods for generating regional/local scale climate change probabilities from coarse resolution CP.net data.  To trial the application of probabilistic climate change information to Agency-relevant case studies (initially for water resources and biodiversity management).  To explore the added-value of probabilistic scenarios for strategic planning and practical lessons learnt from the case studies.  To share the techniques and experience gained from the exemplar projects with a wider community of partner organisations and stakeholders.

OUCE Oxford University Centre for the Environment climateprediction.net aims to…  Sample uncertainty in climate models across –Physics –Initial conditions –Climate forcing  Provide better understanding of plausible future climate changes that can be forecast with one GCM species

OUCE Oxford University Centre for the Environment Experimental Strategy  Distributed public computing – port HadCM3 to windows/linux/mac  Each participant runs a specific experiment –Different model physics, initial conditions, forcing –Currently 17 million model years

OUCE Oxford University Centre for the Environment Phase 1  2 x CO 2 equilibrium experiments –15 years calibration at 1 x CO 2 –15 years control at 1 x CO 2 –15 years at 2 x CO 2

OUCE Oxford University Centre for the Environment ClimatePrediction.net

OUCE Oxford University Centre for the Environment Data Available  Global mean time series  Eight year seasonal climatologies –Surface air temperature –Precipitation –Cloudiness –Surface heat budget

OUCE Oxford University Centre for the Environment Phase 2  Transient simulations with HadCM3 – “hindcast” – forecast  Launched with BBC in February

OUCE Oxford University Centre for the Environment Data Available in Phase 2  More variables  Global mean monthly time series  Regional monthly time series (Giorgi; NAO; MOC)  UK grid-box monthly series  Ten-year seasonal climatologies ( )

OUCE Oxford University Centre for the Environment First Results  Use of CP.Net probabilistic climate change data for water resource assessment in the Thames basin –CATCHMOD: water balance model of River Thames basin –CP.net data available from Experiment 1 –Results and discussion

OUCE Oxford University Centre for the Environment CATCHMOD: water balance model of River Thames basin.

OUCE Oxford University Centre for the Environment River Thames Basin upstream of Kingston gauge and GCM grid-boxes

OUCE Oxford University Centre for the Environment CATCHMOD: parameters  Six key parameters controlling –Direct runoff –Soil WC at which evaporation is reduced –Drying curve gradient –Storage constant for unsaturated zone –Storage constant for saturated zone Wilby and Harris (2005)

OUCE Oxford University Centre for the Environment CATCHMOD  Inputs: daily time series of precipitation (PPT) and potential evaporation (PET)  Output: daily time series of river flow  Parameters :chosen as the ones that best reproduce observed flows for the period

OUCE Oxford University Centre for the Environment CP.net Data  Grand ensemble of 2578 simulations of the HadAM3 GCM  Explores 7 parameter perturbations and perturbed initial conditions  450 IC ensembles (model versions)

OUCE Oxford University Centre for the Environment CP.net variables and CATCHMOD Inputs  8-year seasonal means for: –total cloud amount in LW radiation –surface (1.5m) air temperature –total precipitation rate  Use these to calculate change factors for PPT and PET over Thames  Change factors used to perturb CATCHMOD daily time series of PPT & PET

OUCE Oxford University Centre for the Environment Results: Change Factors PPT (%CF)PET (%CF)Temperature at 2xCO2 PPT vs PET

OUCE Oxford University Centre for the Environment + unperturbed HadAM3 * present day Results: Standard CATCHMOD

OUCE Oxford University Centre for the Environment Results: CP.net and CATCHMOD Q50

OUCE Oxford University Centre for the Environment Results: CP.net and CATCHMOD Q95

OUCE Oxford University Centre for the Environment Factors not Considered  Full set of CP.net perturbations  Emissions uncertainty  Downscaling uncertainty  Alternative model structures (GCM and Hydrological)  Coupled transient climate response

OUCE Oxford University Centre for the Environment Are Probabilistic Approaches Useful?  CP.net provides useful climate information – particularly joint probabilities of key variables  Enable more informed decision making  Issues for Water Utility stakeholders –Understanding the information –Having time and resources to use information –Regulatory constraints –In many cases other (non-climate) factors are more uncertain

OUCE Oxford University Centre for the Environment CP.net parameters ParameterDescription VF1(m/s) Ice fall speed. CT(1/s) Cloud droplet to rain conversion rate. RHCRIT Threshold of relative humidity for cloud formation. CW_sea (1/kgm^3) CW_land Cloud droplet to rain conversion threshold. EACF Empirically adjusted cloud fraction. ENTCOEF Scales rate of mixing between environmental air and convective plume.

OUCE Oxford University Centre for the Environment Potential Evaporation Penman PET is a function of mean air T, mean vapour pressure (vp), sunshine and wind speed Present : calculate monthly Penman PET using observed climate variables for London (monthly long term means , UK national grid) 2xCO2 : calculate monthly Penman PET assuming: wind speed = constant relative humidity = constant thus relative change in vp=relative change in svp relative change in sunshine = - relative change in cloud amount T at 2xCO2= observed T + deltaT vp at 2xCO2= observed vp x (1+CF(svp)) sunshine at 2xCO2 = observed sunshine x (1-CF(cloud)) CF calculated using control and 2xCO2 phases for all the variables.

OUCE Oxford University Centre for the Environment Smoothed frequency distributions and CDFs: Q50 Uncertainties: Climate model parameterization Hydrological model parameterization No downscaling No hydrological model structure

OUCE Oxford University Centre for the Environment Smoothed frequency distributions and CDFs: Q95 Uncertainties: Climate model parameterization Hydrological model parameterization No downscaling No hydrological model structure

OUCE Oxford University Centre for the Environment Smoothed frequency distributions and CDFs: Q95 Uncertainties: Climate model parameterization Hydrological model parameterization No downscaling No hydrological model structure

OUCE Oxford University Centre for the Environment Frequency distribution of flows: annual statistics Uncertainties: CP.net parameter dependence No hydrological model No downscaling No hydrological model structure

OUCE Oxford University Centre for the Environment Frequency distribution of flows: annual statistics Uncertainties: CP.net parameter dependence No hydrological model No downscaling No hydrological model structure

OUCE Oxford University Centre for the Environment Frequency distribution of flows: annual statistics Uncertainties: CP.net parameter dependence No hydrological model No downscaling No hydrological model structure