Coastal & Marine. Environment. Sea Level Rise. Chapter. Mazen Abualtayef Assistant Prof., IUG, Palestine

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1 Sea Level Rise Mazen Abualtayef Assistant Prof., IUG, Palestine

2 What is Sea Level Rise? Sea Level Rise is defined as a mean rise in sea level

3 When sea level rises west How does the slope of the land influence the loss of shoreline? east What happens to the island? Steeper slope Island Gentle slope

4 Tide gauge increase due to climate warming decrease due to climate cooling present sea level

5 Tide gauge decrease due to land rising increase due to land subsidence present sea level

6 What about an area with excessive sediment input, does sea level change? Tide gauge present sea level Sea level remains constant, the container holding the water (oceans) is very large.

7 Relative Sea Level Change Climate warming Glacial ice melts and seawater volume expands Climate cooling More glacial ice forms and seawater volume contracts Land rebound (rising) Rebound of land due to former glaciation and removed Land subsidence (sinking) Withdrawal of groundwater or petroleum

8 Global Warming Processes The Greenhouse Effect is a process that makes the Earth inhabitable This process can lead to an increase in global temperature when greenhouse gases are added to the atmosphere (Source: An increase in global temperature can result in sea level rise due to the melting of glaciers (Source: 37F/automobile_traffic_pollution.jpg) (Source: NASA)

9 Background Ice and snow profoundly affect our climate. During the Northern Hemisphere winter, they blanket up to 16% of the Earth s surface with a bright covering that reflects much of the Sun s radiant energy back to space. During the Southern Hemisphere winter, they cover about half this area. An expected consequence of global warming is a decrease in the Earth s snow and ice cover, which would increase the global absorption of solar radiation and, in the event of a significant melting of land ice, increase sea level. Iceberg

10 Background Ice sheets and glaciers are important reservoirs for fresh water. Approximately 75% of the world s fresh water is stored in ice, the remainder being stored underground or in lakes, rivers and streams. Of the 75% in ice, approximately 91% is held in the Antarctic ice sheet, 8% in the Greenland ice sheet, and the remaining 1% in mountain glaciers.

11 Background Over the past century, sea level has slowly been rising. This is in part due to the expansion of ocean water as it warms and in part due to the addition of water to the oceans through either the melting or the calving off of icebergs from the world s land ice. A vast majority of individual mountain glaciers and ice caps are known to have been retreating, some very rapidly, and their melt and consequent runoff contribute to sea level rise. Although scientific evidence is increasing that on balance, both the Greenland and Antarctic ice sheets are shrinking, it is still uncertain what impact this will have on the world s population. If all the ice melted or otherwise entered into the oceans, global sea level would rise by approximately 70 meters.

12 Global Mean Sea Level from Tidal Gauge observations around world 2.0 mm/year 0.8 mm/year Average Rate ~ 1.8 mm/year

13 Global mean temperatures Warmest 12 years: 1998,2005,2003,2002,200,2006, 2001,1997,1995,1999,1990,2000 Period Rate Years /decade

14 Contribution to Sea Level by Thermal Expansion Rate = 0. mm/year ( ) DMSL (mm) Year

15 DMSL (mm) Coastal & Marine Contribution to Sea Level by Mountain Glaciers : 0.5 mm/year Year

16 Sea Level Budget (IPCC-2007, mm/year) + Thermal Expansion Mountain Glaciers ± ± ± ± Greenland Ice Melt 0.2 ± ± Antarctic Ice Melt 0.2 ± ± 0. Land Water Storage?? = Total of Observed Contributions Observed Sea Level Change 2.8 ± ± ± ± 0.5

17 1. According to observations and measurements, average global increase in sea level is 1-2 mm/year. 2. Mean Sea Level is projected to rise by 0.18 m to 0.59 m by 2100, But with Significant Regional Variations, IPCC 2007)

18 Factors affecting sea level Not directly climate related: Tides Periodic changes due to changing orbital motions of earth & moon Storm surges - Atmospheric effects inverse barometer, tropical storm/hurricane surges Wind-stress driven surge Directly climate related: Isostatic Vertical movement of land Eustatic changes of total sea water mass Steric Thermal expansion of water volume

19 Sea level Coastal & Marine Factors affecting sea level: Astronomical tides Time (days)

20 Factors affecting sea level: Atmospheric variations Inverse barometer effect The inverse response of sea level to changes in atmospheric pressure. A static reduction of mb in atmospheric pressure will cause a stationary rise of 1 cm in sea level Low Atmospheric Pressure 1000mb 20cm 980mb

21 Factors affecting sea level: Storm surges 1. A deep centre of low pressure situated over Scandinavia produces northerly winds. 2. Wind stress forces surface waters into the bottleneck of the English Channel. 3. Flow is restricted by the Straits of Dover and sea levels rise along the adjacent coasts of East Anglia and the Netherlands.. Other key ingredients include high Spring tides and on-shore winds.

22 Factors affecting sea level: Isostatic changes Isostatic changes = vertical land movements Examples: Stockholm, Sweden (Glacial Isostatic Adjustment). Nezugaseki, Japan (abrupt jump in sea level record following earthquake in 196). Fort Phrachula Bangkok, Thailand (sea level rise due to increased groundwater extraction since about 1960). Manila, Philippines (recent deposit from river discharges and reclamation works). Honolulu, Hawaii (a site in the PGR 'far field' without evident strong tectonic signals on timescales comparable to the length of the tide gauge record and with secular trend 1.5 mm/year).

23 Factors affecting sea level: Eustatic changes Eustatic changes = volumetric (mass) changes Glaciers, ice-caps or ice-sheets: Gain mass by accumulation of snow (snowfall and deposition by wind-drift), which is gradually transformed to ice. Lose mass (ablation) mainly by melting at the surface or base with subsequent runoff or evaporation of the melt water. Net accumulation occurs at higher altitude. Net ablation at lower altitude. The mass balance for an individual body of ice is usually expressed as the rate of change of the equivalent volume of liquid water, in m 3 /yr; the mass balance is zero for a steady state.

24 Factors affecting sea level: Steric rise As oceans warm, density decreases and thus even at constant mass the volume of the ocean increases. Thermal expansion (or steric sea level rise) occurs at all ocean temperatures. Water at higher temperature or under greater pressure (at greater depth) expands more for a given heat input. Therefore, the global average expansion is affected by the distribution of heat within the ocean. Salinity changes within the ocean also have a significant impact on the local density and thus local sea level, but have little effect on global average sea level change. The rate of climate change depends strongly on the rate at which heat is removed from the ocean surface layers into the ocean interior if heat is taken up more readily, climate change is retarded but sea level rises more rapidly.

25 Δh (t) = X (t) + g (t) + G (t) + A (t) + I (t) + p (t) + s (t) The components of MSL rise are due to: X is the thermal expansion (steric rise); g is the loss of mass of glaciers and ice caps (eustatic rise); G is the loss of mass of the Greenland ice sheet due to current climate change (eustatic rise); A is the loss of mass of the Antarctic ice sheet due to current climate change (eustatic rise); I p s is the loss of mass of the Greenland and Antarctic ice sheets due to the ongoing adjustment to past climate change (eustatic rise); is the runoff from thawing of permafrost (eustatic rise); is the deposition of sediment on the ocean floor.

26 Sea-Level Rise Impacts Periodic flooding and permanent inundation a whole new floodplain Coastal squeeze Coastal ecosystem migration halted by engineered shoreline defenses Shoreline recession Inland migration of natural shorelines Ecosystem transformation Shift in aereal extent of coastal habitats and habitat relationships Saltwater intrusion Inland migration of salt/fresh surface and groundwater interface

27 Coastal erosion and accretion 1m cm rise in MSL erodes approx 1m horizontally of beach Sea level rise has a profound effect on rate of sedimentation Varying of sedimentation rates -> changing vegetation zones e.g. growth/shrinkage of marshes Storm surges force large quantities of shore-face sediments through inlets -> create tidal deltas/barriers

28 Vulnerable populated regions Large Coastal Cities: Populations >8 million (over 50% of US population live in coastal areas, >110 million) Highly populated Delta regions: Vulnerable to MSL rise

29 Flood and storm damage Coastal region more susceptible to storm surges, flooding, beach/coastal erosion => disruption of activities; danger to life; infrastructure damage 1 m rise in MSL would enable a 15-year storm to flood areas that today are only flooded by 100-year storms Urban flooding: contaminated water supply; drainage/waste systems overwhelmed Flood damages would increase 36-58% for a 30-cm rise in sea level, and increase % for sea level rise greater than 90 cm Source: National Hurricane Service

30 Increased salinity in estuaries Saltwater will penetrate farther inland and upstream in estuaries i.e. estuarine salt wedge. Higher salinity impairs both surface water and human groundwater water supply Saltwater intrusion would also harm ecosystems: aquatic plants and animals e.g. salt marshes, mangroves Higher salinity has been found to decrease seed germination Flooded agricultural land takes a long time to recover from saline water Decline of coastal commercial fisheries e.g. Salinity intrusion has already been cited as primary reason for reduced oyster harvests in Delaware and Chesapeake Bays in the USA

31 Potential Impacts on the Natural Loss of habitat such as coral reefs and wetlands may have significant impacts in the coastal zone

32 Potential Impacts on Humans and the Built As coastal populations increase, vulnerability of those populations to sea level rise increases as well. 7 million people live below the 1 meter contour line in Bangladesh. (Source: climatechange.htm)

33 Sea-Level Rise Policy Continuum Coastal County or Municipal Government

34 Protection To ensure adequate protection of the built environment through soft and hard shoreline stabilization that seeks to maintain a static shoreline position within the City.

35 Hard Stabilization Soft Stabilization Living Shorelines Seawall - Kailua-Kona, HI Motorway Dike - Netherlands Living Shorelines

36 Protection Considerations Advantages Protects important private and public infrastructure Creates investor certainty Can be used with other strategies Disadvantages Requires long-term maintenance May be unsustainable (depending on SLR rates) Ecologically problematic Loss of sandy beaches, coastal squeeze

37 Accommodation To accommodate increasing sea levels and the additional flooding that will result by adapting the built environment and enhancing the resiliency of the natural environment where it is economically and ecologically practicable to do so.

38 Floating Bridge - Seattle, WA Floating House Brad Pitt s Make it Right Foundation, New Orleans, LA Multi-family floating canal houses - Scheepstimmermanstraat, Amsterdam House on stilts New Orleans, LA

39 مطول Prolonged: قابلية اإلصابة Vulnerability: Accommodation Considerations Advantages Allows development to proceed in transition areas and where SLR is uncertain threat of sea level rise is prolonged Minimizes damage Disadvantages Increases vulnerability Alters the characteristics of shorelines Short-term solutions that eventually lead to protection or managed relocation strategy

40 Managed Relocation To Reduce vulnerability in the built environment and preserve coastal ecosystems through changes in land use and the orderly abandonment and /or landward relocation of structures and associated infrastructure

41 Managed Relocation Considerations Advantages Promotes ecosystem migration Minimizes threats to humans Financially sustainable in the long-term Potentially expensive for areas that are significantly developed Disadvantages Politically problematic to implement May be subject to legal challenge Relocation issues

42 Scenarios by Projected SLR for the Nile Delta CASE STUDY

43 Station Average Annual ASLT (Cm) Trend and Accelerated Sea Level Rise (ASLR) Measured Along the Nile Delta Coast. (CoRI-2007), First Scenario Sea Level Rise (Cm) 2025 Sea Level Rise (Cm) 2050 Sea Level Rise (Cm) 2075 Sea Level Rise (Cm) 2100 Alex Al-Burullus Port Said

44 Year Expected SLR Till 2100 by Projected Increase in Air Temperature (B1 Scenario ( Temperature (ºC) ASLR at Alexandria 7.0 cm 16.0 cm 27 cm 28 cm ASLR at Al-Burullus 8.75 cm 19.5 cm cm 35.0 cm ASLR at Port Said cm 39.5 cm 6.3 cm 72.5 cm

45 Total affected area and its percentage to the Nile Delta area According to CoRI measurements till 2100 Year (Without Mohammed Ali wall and zero level for lakes borders) Total Area Affected (km2) Total % of the Nile Delta Area

46 Total affected area and its percentage to the Nile Delta Area According to CoRI measurements till 2100 Year (With Mohammed Ali wall lakes borders) Total Area Affected (km2) Total % of the Nile Delta Area

47 Muhammed Ali Sea Wall Protected Cultivated Low Lands (1.5m - 2.5m Below Sea Level)

48 Muhammed Ali Sea Wall Abu Quir Bay Low Lands ( m Below Sea Level) Protected By Muhammed Ali Sea Wall

49 Ras Al-Bar Resort Has Gained Lands After the Construction of Protection Works Detached Breakwater

50 Adaptive Process and Policies Sand dunes systems should be treated as the first defensive line for the Nile Delta. Decision makers in coastal governorates as well as concerned ministers should be aware of the importance of sand dunes systems and their role in protecting the coastal zone of the Nile Delta. Consideration should be paid to coastal lakes as one of the most appropriate adaptive measure against sea level rise. Coastal international road should be considered as the second protection measure and studies to support it are urgently required. Coastal protection constructions need regular maintenance and should be considered in any coastal zone management plans. The northwest coast extended from Alexandria to the Egyptian-Libyan borders is not vulnerable as it has elevation more than 10 m above average sea water level.

51 References 1. Global ice and snow presentation, National Aeronautics and Space Administration, NASA 2. ENVI310: Coupled Ocean & Atmosphere Climate Dynamics 3. Krystle Macadangdang, LL.M, Melissa Newmons, J.D. Sea Level Rise Ready.. Prof. Ibrahim Elshinnawy, Vulnerability Assessment and Adaptation Policies for C C Impacts on the Nile Delta Coastal Zones.