Global Change In Sea Level

Seds Lab 9

Currently Rising

May lead to

• Loss of property and coastal habitats

• Flood risk and potential loss of life

• Loss of renewable/subsistence resources

• Loss of Tourism, Recreation and Transportation Functions

• Loss of non-monetary cultural resources

• Loss in agriculture/aquaculture

History

• Evidence from Fossil and Sedimentary Record

• Correlation in time in significant part of sedimentary record

• Oxygen isotope evidence from plankton or ice cores

Mass Extinctions

• Strong relationship between Eustatic sea level and Mass Extinctions

• 5 of 6 show evident correlation

Ordovician Permian Triassic Cretaceous Late Devonian

Methods of Sea-Level Change

Isostacy• Regional continental uplift

Glaciation• Global (glacieustatic)

Greenhouse Effect• Expansion of water at higher T

Tectonic activity• Displacement due to mid-oceanic ridges, or Continental Flood

Basalts (tectonoeustatic)• Increased sedimentation due to continental uplift• Breakup of super continents, creation of less dense Oceanic crust

Modern Sea Level Rise

Various Projections• 18-60cm by 2050, 24-108cm by 2080 (Gornitz)• 100yr storm flood could be reduced to 19-68yr by 2050, 4-60yr by 2080• Rates of Beach Erosion will increase 3-6 times by 2050, 4-8 times by 2080• 9-88cm by 2100, 12m in the next 1000 years (Nichols)

Once lost, a return to present atmospheric conditions will NOT be adequate to regenerate modern ice sheets

Consequences

• Loss of property and coastal habitats

• Flood risk and potential loss of life

• Loss of renewable/subsistence resources

• Loss of Tourism, Recreation and Transportation Functions

• Loss of non-monetary cultural resources

• Loss in agriculture/aquaculture

Canada Susceptibility

Map based on 7 attributes• Geology• Modern rate of sea level rise• Coastal type• Relief• Tidal range• Wave energy• Modern rates of erosion

Eg. A highly sensitive area has low relief, a high rising sea level already, a high tidal range, high tidal energy, high rates of erosion today, and is composed of beaches or marshes

• High Risk: Atlantic Canada, the Beaufort Sea and the Frazer Delta

What can we do?

• A mitigated sea level rise is likely to be less devastating

• Correlation with paleo-sea level and atmospheric CO2 is observed but direct consequence of burning of hydrocarbons uncertain

Bibliography• Couch S, Gornitz V, 2002. Impacts of Sea Level Rise in the New

York City Metropolitan Area. Global and Planetary Change. 32: 61-88

• Hallam A, Wignall P, 1999. Mass Extinctions and Sea Level Changes. Earths-Science Reviews. 48:217-250

• Herrmann A, Huapt B, Patzkowsky M, Seidov D, Slingerland R, 2004. Response of late Ordovician Paleoceanography to changes in sea level, continental drif, and atmospheric pCO2: otential cases for longterm cooling and glaciation. Paleo 210:385-401

• Hitz S, Smith J, 2004. Estimating Global Impacts from climate change. Global and Environmental Change. 14:201-218

• Leeder M, 2003. Sedimentology and Sedimentary Basins: From Turbulence to Tectonics. Blackwell, pp 258-266

• Monroe J, Wicander R, 2004. Historical Geology. Edited by Dodson K. Thomson Brooks/Cole, pp192, 213, 335

• Nicholls R, Lowe J, 2004. Benefits of Mitigation of climate change for coastal areas. Global and Environmental Change.

14:229-244• UNEP-www.grida.no/climate/vital/33.htm

Thanks to John Shaw of the GSC for the swift and concise response to my email