Michel Rixen, WCRP Joint Planning Staff World Climate Research Programme EAG-FRT I December 2011 Geneva, Switzerland Michel Rixen, WCRP Joint Planning Staff

(WCRP Strategic Framework 2005-2015). Mission & Objectives World Climate Research Programme supports climate related decision making and adaptation planning by coordinating research required to improve: climate predictions and understanding of human influence on climate “for use in an increasing range of practical applications of direct relevance, benefit and value to society” (WCRP Strategic Framework 2005-2015).

The Interdisciplinary Nature of Climate Science Atmosphere, Oceans and Climate Cryosphere and Climate Atmospheric Chemistry and Dynamics Water, Energy and Climate Meeting the Information Needs of Society Activities in Support of Key Deliverables Decadal Variability, Predictability and Prediction Sea-Level Variability and Change Climate Extremes Centennial Climate Change Projections Seasonal to interannual Climate Prediction Sub-seasonal to seasonal Predictions Regional Climate Science and information Activities in Support of WCRP Integrating Themes Climate-Quality Data Sets and Analyses A New Generation of Climate/Earth System Models Next Generation of Climate Experts: Developing Capacity Regionally and Globally 3

Global Framework for Climate Services

WCRP Open Science Conference 24-28 October 2011 Denver, Colorado, USA http://conference2011.wcrp-climate.org Promoting, Facilitating and Coordinating Climate Research in Service to Society Main outcome: ”actionable science“: scientists and private sector need to work together toward actionable climate information

Uncertainty, risk and decision making Probability and cost matter No risk estimate w/o reliable uncertainty/PDF No decision making w/o risk estimate From simple models’ spread/standard deviation to complex non-linear full PDF

WCRP Extremes crosscut Decrease in return period of extreme temperatures (left) and precipitation (right) for IPCC scenarios B1, A1B and A2

CORDEX Regional downscaling

Multi-model ensembles: more robust predictions and statistics

First CORDEX Africa projections based on CMIP5 Representative Concentration Pathways (radiative forcing based)

Joint WCRP/WWRP effort on sub-seasonal to seasonal predictions

Points for discussion International programs with key players WGCM/CMIP5: coupled modeling, now-2100 WGSIP: seasonal to interannual WGNE: understanding processes and parameterization YOTC/MJO: increase predictability, sub-seasonal CORDEX: regional downscaling GEWEX: strong extremes expertise Cross-cuts: extremes and droughts, sea level and cryosphere, tropical cyclones, etc

Points for discussion More research: Variability versus trend Observing systems and reanalyses Coupled modeling and data assimilation Multi-model (super-)ensembles, uncertainties, indices Downscaling techniques Process studies and predictability Extremes

Conclusions WCRP provides the scientific foundation for climate research on broad spatio-temporal scales Capturing/predicting uncertainty is central to risk management and robust decision making Multi-models ensembles are necessary

Thank you for your attention! mrixen@wmo.int