World Climate Research Programme Climate Information for Decision Making

1. World Climate Research ProgrammeClimate Information for Decision Making Ghassem R. Asrar Director, WCRP

2. Outline • Science Based Decision Making • World Climate Conference-3: Climate info. for better future • OceanObs09: Ocean observations for society • ICSU visioning: Environment & sustainable development • WCRP Contribution • Seasonal Predictions • Decadal Predictions • Regional climate predictions • Sea Level variability and change

3. Seasonal Climate Prediction • WCRP, through its Working Group on Seasonal to Interannual Prediction (WGSIP), • Launched the Climate-system Historical Forecast Project (CHFP) a multi-model and multi-institutional experimental framework for sub-seasonal to decadal complete physical climate system prediction http://www.clivar.org/organization/wgsip/chfp/chfp.php • CHFP will provide: • A baseline assessment of seasonal prediction capabilities using the best available models of the climate system and data for initialization

4. Seasonal Climate PredictionChallenges • Quantifying Forecast Uncertainty Due to Uncertainty in Model Formulation • Multi-Model Helps, but Ad-Hoc • Quantifying Forecast Uncertainty Due to Uncertainty in Observational Estimates • Initial Condition Problem • Model Error • Need for International Coordinated Effort at Improving Models (Multi-Model is Not an Excuse for Neglecting Model Improvement) • Climate System Component Interactions • Coupled Ocean-Land-Ice-Atmosphere • External Forcing vs. Natural Variability • Quantifying the Limit of Predictability

5. Seasonal Prediction-South Africa Rainfall forecast issued in Dec. 2008 by a multi-model operational Seasonal Forecast by the South African Weather Service. 10%

6. additional predictions Initialized in ‘01, ’02, ’03 … ‘09 100-yr “control” & 1% CO2 hindcasts without volcanoes 10-year hindcast & prediction ensembles: initialized 1960, 1965, …, 2005 alternative initialization strategies prediction with 2010 Pinatubo-like eruption 30-year hindcast and prediction ensembles: initialized 1960, 1980 & 2005 extend ensembles from O(3) to O(10) members atmos. chemistry &/or aerosols &/or regional air quality prescribed SST time-slices Decadal Climate Experiments WCRP, through its Working Group on Coupled Modelling (WGCM) • has developed the coupled-model intercomparison project (CMIP5) that coordinates the decadal predictability/prediction experiments • will provide the foundation for the simulations to be assessed as part of the IPCC AR5

7. Decadal Climate Predictability Observed decadal climate variability in Pacific and Atlantic sectors (left) and first attempts to make decadal predictions (right)

8. Regional Climate The need for climate information at the regional-to-local scale is one of the central issues within the global change debate. In 2008 WCRP established a Task Force on Regional Climate Downscaling (TF-RCD), whose mandate is: • to summarize the shortcomings, difficulties and scientific basis of existing downscaling methods to serve as guidance to the climate change assessment community; • to develop a framework for evaluation and intercomparison of regional downscaling techniques.

9. Schematic depiction of the primary uncertainties in regional climate change projections. RCD Configuration (Multiple models) AOGCM Configuration (Multiple AOGCMs) Systematic Errors (Model eval./impr.) Uncertainty in regional climate projection Emis./Conc. (Multiple Scenarios) Regional cover (Multiple regions) RCD approach (Multiple RCD methods) Internal variability (Multiple realizations) Regional Climate

10. Regional Climate: Africa - Example January-February-March mean precipitation for 1998-2008 period.

11. Regional Climate:Africa - Example July-August-Septmeber mean precipitation for 1998-2008 period.

12. Sea-Level Variability and Change The main challenge is to address the uncertainties in the projection of future sea-level changes due to recently discovered processes in the Greenland and Antarctic regions. The joint WCRP/IOC Task Group on Sea-Level Variability and Change (TF-RCD) was established with the mandate to: • Improve further our ability to monitor, explain and predict changes in global and regional sea level and associated environmental factors. • Make available this information for stakeholders and policy-makers

13. Sea-Level Variability and Change:Regional Impacts Climate variability affects the regional distribution of sea-level rise. CSIRO - Australia

14. Sea-Level Variability and Change:Regional Impacts 20th Century – Fort Denison • 20th Century sea-level rise has already caused a significant increase in extreme events - three-fold increase post-1950. • By 2100, 1 in 100 year events are projected to happen several times a year! 2.35 2.30 +0.08m Pre-1950 2.25 2.20 Post-1950 x3.1 2.15 Sea Level (m) 2.10 2.05 2.00 0.1 1 10 100 Return Period (Years)

15. Conclusions WCRP will continue to: • Provide Scientific Knowledge on climate variability and change. • Facilitate research on climate projections and predictions on centuries, decades and seasons. • Place a major emphasis on regional climate variabilityand change with special attention to extreme events. • Support development and delivery of climate information for decision makers. • Sponsor training and development of next generation of regional and global climate experts.