1. Impacts of Global Sea- Level Rise: The AVOID Analysis Robert Nicholls and Sally Brown School of Civil Engineering and the Environment and the Tyndall Centre for Climate Change Research University of Southampton Southampton SO17 1BJ UK r.j.nicholls@soton.ac.uk Earth Systems Science 2010

2. Plan Introduction Methods Results Conclusions

3. Global sea-level rise (IPCC, 2007, AR4 WG1)

4. DIVA (Dynamic Interactive Vulnerability Assessment)

5. Input Parameters A1B socio-economic scenarios Unmitigated vs. mitigated sea-level rise scenarios No protection versus quazi-optimum protection scenarios

6. Sea-level rise scenarios

7. A1B.2016 SLR scenario family

8. A1B.2030 SLR scenario family

9. Output Parameters Wetland Area (Natural Systems) Floods (Human Systems) Dike Costs (Adaptation)

10. Saltmarsh losses 2080s

11. Mangrove loss 2080s

12. Coastal Flooding Exposure –flood plain population (1 in 1000 year flood plain) Risk –expected annual frequency (or damage) Exposure x Probability (considers adaptation strategies)

13. Coastal flood plain population 0 50 100 150 200 250 300 No mitigation 2016.R 2030.R No mitigation 2016.R2030.R No mitigation 2016.R2030.R 2020s2050s2080s Millions of people 10th percentile 50th percentile 90th percentile

14. People flooded and no adaptation change in expected annual frequency

15. People flooded and adaptation change in expected annual frequency

16. Protection costs in 2050s to 2080s (1995 dollars) 0 5000 10000 A1B 2016.R2030.R A1B 2016.R2030.R 2050s2080s Cost (US dollars/year) (billions) 10th percentile 50th percentile 90th percentile

17. Results -- Summary Emission reductions will slightly reduce the global losses of saltmarsh and mangrove after the 2050s -- 4 to 7% of the global stock saved by the 2080s; The size of the coastal flood plain population is insensitive to emission reductions; Emission reductions will reduce the global number of people experiencing flooding by 2050, and the benefits are substantial by 2100, assuming no adaptation; However, flood impacts still increase by 10 to 20 times under mitigated scenarios and the reductions in flood impacts represent delayed (to the 22 nd Century) rather than avoided damages; Assuming quazi-optimum adaptation greatly reduces the benefits of emissions reduction identified above.

18. Conclusions For coasts, emission reductions mainly delay rather than avoid 21 st Century impacts; This reflects the commitment to sea-level rise; Need more information about mitigation and large sea-level rise and storms; Collectively, this supports the IPCC AR4 conclusion: the most appropriate response to sea-level rise for coastal areas is a combination of adaptation to deal with the inevitable rise, and mitigation to limit the long-term rise to a manageable level.

19. Impacts of Global Sea- Level Rise: The AVOID Analysis Robert Nicholls and Sally Brown School of Civil Engineering and the Environment and the Tyndall Centre for Climate Change Research University of Southampton Southampton SO17 1BJ UK r.j.nicholls@soton.ac.uk Earth Systems Science 2010