1 BHS Third International Symposium, Managing Consequences of a Changing Global Environment, Newcastle 2010 © British Hydrological Society The CREW project: Towards a toolkit for the use of probabilistic climate change projections S. Blenkinsop 1 , S. Hallett 2 , I. Truckell 2 and H.J. Fowler 1 1 School of Civil Engineering and Geosciences, Newcastle University,UK; 2 National Soil Resources Institute, Cranield University, UK Email: s.blenkinsop@ncl.ac.uk Abstract The CREW (Community Resilience to Extreme Weather) project aims to develop a set of tools for improving the capacity for resilience of local communities in south-east London to the impacts of extreme weather events. Here, probabilistic projections of local climate derived using the UK Climate Projections (UKCP09) Weather Generator for two future time periods, the 2020s and 2050s and assuming a medium emissions trajectory, are presented. These show that by the 2050s the central estimate of mean July maximum temperature is projected to increase by ~3°C whilst precipitation is projected to decrease by ~21%. Within CREW these changes are applied to produce probabilistic projections of a series of weather-related hazards, demonstrated here by the vulnerability to clay related soil subsidence which is in part related to the Potential Soil Moisture Deicit (PSMD). By the 2020s increased vulnerability is likely across the south and particularly south-east of the region and by the 2050s this is extended to the central part of the region. These changes are illustrated within the wider context of the CREW project, particularly its aims to develop a toolkit to allow different users to evaluate potential impacts, manage the impacts on the ground and develop intervention strategies. Introduction Society faces considerable challenges from the prospect of climate change; however the large-scale climate models used to provide projections of future climate are not designed to be applied to the problem of assessing regional- and local-scale impacts of climate change. Furthermore, projections of future climate derived from models are associated with signiicant uncertainties, especially on regional and local scales (Randall et al., 2007). This uncertainty principally arises due to natural variations in climate, uncertainty in the trajectory of future greenhouse gas emissions and also in the models themselves (Collins, 2007). Although such uncertainties may be addressed through the use of probabilistic climate change scenarios, to date these have only been employed to a limited extent in impact studies. However, New et al. (2007) have demonstrated that the output from large model ensembles have the potential to add much useful information to decision- making processes in climate change impact assessments. The Community Resilience to Extreme Weather (CREW) project seeks to use state-of-the-art probabilistic climate change scenarios from the UK Climate Projections (UKCP09; Murphy et al., 2009) to further our understanding of the probability of current and future extreme weather events (EWEs) and their likely socio-economic impacts. Whilst initiatives, such as the Stern Review (Stern, 2006), consider high-level socio-economic impacts they do not provide the sub-regional or local estimates relevant at the level of local communities and individuals. Using an area of south-east London as a case study, the CREW project is investigating a range of hazards at the local level including heat waves, looding from pluvial and tidal sources, wind, drought and subsidence. The project will use innovative physical modelling methods integrated with social research to improve understanding of the risks, vulnerabilities, barriers and drivers that affect the resilience of a local community to climate change. It is envisaged that this will facilitate an adaptation-based approach by investigating the opportunities for improving local communities’ adaptive capacity and thus increase resilience to climate change (Smit and Wandel, 2006). The approach will be based on the needs of key stakeholders, comprising householders, small and medium size enterprises (SMEs) and local policy/decision makers. A key means of delivering information to these groups is the development of a ‘What-If Scenario Portal’ (WISP), a web-based information dissemination tool for integrating the project outputs to deliver maps, reports and guidance on impacts and resilience measures for EWEs. In this paper we demonstrate the CREW framework to describe how UKCP09 probabilistic scenarios may be generated using a stochastic weather generator and demonstrate the nature of the projections by summarising the main climatic changes in this area. These are used to provide projections of future vulnerability to subsidence, one of the hazards considered in the CREW project. Finally, the end user delivery of this information via the WISP tool is described. Study area and data The South East London Resilience Zone (SELRZ) covers an area of approximately 380 km 2 comprising the ive London boroughs of Lewisham, Greenwich, Bexley, Croydon and Bromley, stretching from the Thames in the north to the fringes of the North Downs to the south (Figure 1). At the 2001 census the ive boroughs had a total population of around 1.3 million people whilst south-east London in general contains over 15% of London’s industrial land area, provides over 500 000 jobs and includes part of the Thames Corridor, designated a national priority regeneration corridor. Furthermore, the London Plan (Mayor of London, 2008) designates this area important for London’s strategic objectives with capacity for up to 55 000 additional homes by 2016 and over 100 000 additional jobs projected up to 2026. Among the key strategic priorities for south-east