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Sea Level Rise and Extreme Events

Sea Level Rise and Extreme Events. Bangkok, October 2012. Climate Change Projected to Cause Sea Levels to Rise. Warmer seas will expand (IPCC 2007) Likely effect 40-100 cm by 2100 Melting ice on land can also raise sea levels (IPCC 2007)

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Sea Level Rise and Extreme Events

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  1. Sea Level Rise and Extreme Events Bangkok, October 2012

  2. Climate Change Projected to Cause Sea Levels to Rise • Warmer seas will expand (IPCC 2007) • Likely effect 40-100 cm by 2100 • Melting ice on land can also raise sea levels (IPCC 2007) • Big concern is Greenland which could cause sea levels to rise several meters

  3. Primary Impact is Coastal Infrastructure • Rising seas will inundate coastal infrastructure and coastal land • Primary loss is infrastructure • Adaptations • Soft and dynamic ecosystems based responses • Move infrastructure inland • Build hard structures (walls) to protect • Raise structures

  4. Economic Analysis • Comparing value of lost infrastructure (inundation) with cost of protection (sea walls), economic analysis suggests it is worthwhile protecting dense urban developments (Yohe et al 1996) • Economic, environmental and social costs/benefits of rural lands will need to be examined; potential trade offs in protecting urban/rural land; equity issues • Faster SLR, earlier adaptation needed and more frequent and more costly improvements

  5. Example: Location with High Economic Value Infrastructure/Low economic value lands • Compare value lost from inundation to cost of sea walls • Examine urban buildings, beaches, marshes, and mangroves • Suggests worth protecting buildings and high valued beaches • Not worth protecting low valued beaches, marshes, and mangroves if sea level rise over 0.6m

  6. Singapore Urban SLR in 2100(Ng and Mendelsohn 2005)

  7. Beach Protection Singapore(Ng and Mendelsohn 2006)

  8. Extreme Events • Storms: tropical cyclones, extra tropical storms, thunderstorms, tornadoes, hail • Extremes: flooding, drought, heat waves, cold spells • Lead to economic damages (USD) and deaths • Climate change may exacerbate impacts

  9. Projecting Changes in Extreme Event Outcomes • As GDP and populations increase, the damages from many extreme events will increase- more in harm’s way • As income increases, deaths are likely to fall- society and people take precautions

  10. Asian Damages in 2010 and 2100 (million USD/yr)

  11. Asian Annual Deaths in 2010 and 2100

  12. Projecting Climate Change Impact on Extreme Events • Unclear how climate change will alter local storms • Higher temperatures and precipitation will increase mean values • Unclear how climate change will alter the distribution of precipitation and temperature around the new mean • Some evidence that intensity of tropical cyclones will increase

  13. Tropical Cyclones • Examine 4 climate models in 2100 • Examine how climate scenarios affect tropical cyclones • Calculate damage per cyclone • Estimate change in damage

  14. Change in Tropical Cyclone Power by Ocean Basin

  15. Estimate Climate Impacts • Calculate future baseline damages (current climate) • Calculate future damages with future climate • Subtract baseline from future damages with future climate to get net climate impact

  16. Climate Change Damages in AsiaFrom Tropical Cyclones in 2100 Billion USD/yr

  17. Increased Intensity • Not clear that the frequency of tropical cyclones will change • Some support for increasing intensity of largest storms • Currently, 10% worst storms cause 90% of damage from tropical cyclones • With climate change, 10% worst storms may cause 93% of damage

  18. Climate change increases frequency of high damage storms

  19. Conclusions SLR • Moderate sea level rise is extremely likely but can be relatively cheaply adapted to over time • Sea level rise from 2-5 meters, although less likely, would be more difficult to manage and would require a combination of defense and retreat

  20. Conclusions-Extreme Events • Frequent small storms are reasonably easy to manage with early warning systems and moderate precautions (building codes, hard structures) • Cat 4-5 tropical cyclones are more difficult • Costly to protect against powerful storm • Low benefit since they occur locally only once in 100 or 1000 years

  21. Extreme Events Continued • Food aid has been a very successful adaptation to droughts reducing deaths dramatically • Deaths from most extreme events are falling as countries get wealthier

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