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Effects of climate change on the North sea coastal zone. NAG-Coast

Effects of climate change on the North sea coastal zone. NAG-Coast. Background An increasing knowledge on expected scenarios for sea level change , including melting of glaciers and ice caps

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Effects of climate change on the North sea coastal zone. NAG-Coast

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  1. Effects of climatechangeon the North seacoastal zone.NAG-Coast • Background • An increasingknowledge on expected scenarios for sealevelchange, including melting of glaciers and icecaps • A betterunderstanding of the expected future wheatherconditions – especially storm patterns and frequencies, wavehigths, etc. • A lackinclusion of geology and slowearthmovements • A lack of a harmonisedcompilation of coastalvulnerability in a geologicsence (erosion, subsidence, flooding, progadation etc.) A need to act in an uncertainworld

  2. The future of ice sheets and sea-level rise David Vaughan and the ice2sea Consortium

  3. Contributions to sea-level change

  4. Possible future sea-level rise? Pfeffer “plausible limit” Vermeer and Rahmsdorf, 2009 Deltacommisee upper IPCC AR4 Upper Continuation of 1870-present = IPCC AR4 lower

  5. Regional sea-level rise (Gravity component) • Relative sea-level rise in 2100 (upper bound scenario)

  6. Local impact of the differentsources Antarctica Thermal+circulation High Mid Greenland Isostasy High Mid Glaciers High Mid Metres by 2100 Ice masses Ocean & land

  7. Recent observed global sea-level rise 3.2 mm/year 2.0 mm/year Satellites 0.8 mm/year Tide gauges Source – Steve Nerem

  8. Contributions the earthmovements • Tectonicuplift or subsidens • Uplift due to erosion – subsidens due to deposition • Isostaticadjustment due to loading-unloading (Ice-cover) Difficult - but may bo not impossible – seperatedifferentisostatic processes. Long time series based on coastlines is needed as the local true eustaticchangesneed to beisolatedfirst

  9. LiDAR-technologyGlobal z-precicionsbetterthan 4-6 cm, localprecision 1 cm 1 km

  10. The Kattegat Curve cm Calenderyear

  11. Establishment of regional reference level • Uses tide gauges outside the localtectonic zone (ca. 1850-2009) • UseHirthals and Varberg – parallel to the isobase line • And Smøgen (Gothenburg) and Hornbæk perpendicular to isobase line • Then a plane canbedefined and then a match in the Læsø eustaticcurvecanbeobtained and adjusted • Obtained a regional eustaticcurve for 900 years

  12. Defininglocal recent movement • Time gauge curvescannowbecompared to eachother and adjusted for the regional isotsticmovements. • Then the localisostaticmovement (to day= average for 150 years) canbedefined • The geologicalknowlegde is used in the explanation of variation • A new isostaticmap of ongoingmovementscanbeestablished

  13. Landrise (mm/yr) determined on the basis of 26 long term tide gauges and the ASL Kattegat Curve

  14. EMODNET sediment map Danish North Sea

  15. Mobile sand Danish North Sea

  16. Map of coastaldeposits Weichseliantill Hill island Meltwaterplain

  17. Adaption to rising sea level coastal vulnerability – coastal type

  18. 1meter sealevel rise

  19. Results and problems The Kattegat curve is a coherentASL-curve of the last 900 yearsshowing a Medievalmaximumaround AD 1200, a relative Little Ice Age low-stand by ≈40 cm in the period 1250 and 1750, and cyclic Atlantic Multidecadal Oscillations by ≈10 cm with tops around 1790, 1860, 1920-50 and at the present. The ASL-curve shows a larger general SL-risethannormallyfound. However, ”the late Cenozoic isostatic system” is a normallyunconsidered land-rise due to precedingbedrock erosion of western Scandinavia as well as ≈1.5-2 km sediment-load of the central North Sea during the Plio-Pleisto-Holocene. If unrecognised, thiseffectwouldlead to underestimation of the ASL-riseduring the lateHolocene. Similar erosion/sedimentation induced isostatic effectsareactivearound the British Isles, Greenland, and the Atlantic coast of North America.

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