Review of sea level variability

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A Review of Sea Level Variability

Damilola Oluwatobi Shyllon3460359

Rise

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Measurement of SLVCauses of SLV

Effects Of SLV

Forecasts of SLV

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SLV Measurements Causes Effects Forecasts

• Sea level variation measurements started in late 17th to early 18th century

• Measurements with Tide gauges started in the mid 18th century at Sheerness, United Kingdom

• First long tidal observation recorded was in 1854 in San Francisco

• In the 19th Century spread through Europe, the UK, Netherlands, Sweden, France, Poland and in that same period to the sub continent of Australia

• Satellite Altimetry was used to measure SLV since 1993 with the launch of the Topex/Poseidon satellite in 1992.

• Current global sea level rise rate is (3.3 ± 0.4 millimeters) per year and regional sea level rise varies at between 5 and 95% of this value.

Background of SLV Measurements


Source: Douglas, B. C. (1997). Global sea rise: A redetermination. Surveys in Geophysics, 18, 279-292.

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Methods of SLV Measurements:

• Tide Gauges

• Satellite Altimetry

• Proxy Records

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Tide Gauge Measurements

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Other Types of Tide GaugesFloat Gauges Acoustic Gauges

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Radar Gauges

Radar Gauges are tide gauges that work on the principle of radar. They are made up of downward looking sensors that can be mounted over the side of a wharf or any permanent structure that gives a clear view of the water and the need to construct a stilling well is removed.

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Challenges of Tide gauge Measurements

• Positioning of the tide gauges

• Shift in plate tectonics and other earth movements

• Local subtle movements of the land

• Seasonal variations or anomalies


Satellite Altimetry Measurements• Began in 1993 with the launch of the Topex/Poseidon

Satellite

• In 2001, the Jason-1 satellite was launched

• In 2008, the Jason-2 satellite

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Satellite Altimetry Measurement Principle

CNES


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Sea level reconstruction from tide gauge data

(Meyssignac & Cazenave, 2012).

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Error Sources of Satellite Altimetry Measurements

• Geoid Modeling Errors

• Effects of Temporal Variations in the Ocean Surface

• Propagation Medium Corrections

• Size of the Beam Footprint

• Instrument errors

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Sea level variation occurs in two dimensions, namely: Global and Regional Sea level variation.

Causes of global SLV

• Ocean Warming

• Mountain Glaciers

• Greenland and Antarctica Ice Sheets

Causes of Regional SLV

• warming of ocean water causing an expansion of the water mass

• change in levels of the continental land masses with change in location

• Variation in ocean currents

• extraction of groundwater or petroleum exploration/exploitation in a coastal area

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Effects of Sea Level Rise

• Erosion of beaches

• Flooding and storm damage

• Salt intrusion into aquifers and surface waters

• higher water tables

• Increased budgets for rebuilding of damaged areas due to

flooding

• Beach nourishment programs

• Where farmland flooding occur it leads to excessively salty

farmlands rendering the farmlands

• threatening of coastal ecosystems and disappearance of coastal

wildlife


Effects of Regional Sea Level Rise on Florida

Map credits: Jeremy Weiss PhD, University of Arizona

• more than 100 Florida

towns live on land 4 feet

below sea level

• salt water is pushing

through porous bedrock

• Retreating shoreline

• Coastal Erosion

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Effects of Regional Sea Level Rise on Netherland• Netherland is geographically located on a low lying delta and more

than a third of the land mass lies below 1 meter above sea level

• They’ve fought the effects of sea level since the 9th century

• The Dutch have experienced several sea storms and flood damage but most notable is the storm of 1953 that claimed 1853 casualties and flooded 165 000 hectares

• The first floods documented occurred in 838 and that led to 2437 casualties, another was in 1014 which was also as catastrophic as the former

• The St. Elizabeth floods, ( The Elizabeth 1 in 1404, The Elizabeth 2 in 1421)

• Other prominent floods include the St. Felix flood (1530), the All saints flood (1570), the Christmas flood (1717), the Zuider Zee flood (1916). 18


Effects of Sea Level Rise on Netherland

The Dutch Sand Engine as seen in 2012

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Effects of Sea Level Rise on Netherland

A so-called "Smart Dike," which contains embedded sensors that relay real-time status reports on the condition of the dike to decision makers

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Effects of Sea Level Rise on the Maldives

• The Maldives, a collection of about 1200 islands in the Indian oceans has its highest point at 8 feet above sea level

• In December of 2004, the islands were inundated by a tsunami that killed 82 people and displaced 12600

• The IPCC forecasts that climate change will lead to milder winters in North America and Europe and this will lead to people not travelling from there to the Maldives.


NOAA, 201422

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IPCC AR4 2007 Sea Level Rise Scenarios and Forecasts

IPCC, 2007


(Thomson et al., 2011).

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(Grinsted, Moore, & Jevrejeva, 2010) 25


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(Rahmstorf, 2007)

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What the Forecasts Suggest Regionally

• Low lying islands such as the Maldives will be inhabitable by the year 2100 or worse totally submerged.

• Florida is already facing the impacts of sea level rise and with the forecasted increase in the rate of sea level rise, the adverse effects will hit Florida geographically and economically .

• The Netherlands risks being flooded by the river Rhine.

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THE END ?

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• The IPCC’s AR5 released in November 2013, agrees that sea level forecast in the was quite optimistic in the 4th report owing to the fact that sea level rise has accelerated at a higher rate due to more emissions from industrialization resulting in increased global warming ;

• There is an increase in understanding of the contribution of Ice sheets and Glaciers to Sea Level Rise

• They also dismissed forecasts from most researchers over the years highlighting that they were mostly bias to one factor or have a biased approach.

• Factors considered include; Thermal expansion, Glaciers, Greenland ice sheet, Antarctic ice sheet, Greenland ice-sheet rapid dynamics, Antarctic ice-sheet rapid dynamics and Land water storage

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Some Discredited forecasts mentioned in the IPCC AR5

• Hansen et al. (2007) giving 5m by 2100, • Pfeffer et al. (2008) constructed scenarios of

0.8 m and 2.0 m, • Katsman et al. (2011) 1.15 m by 2100, • 1.21 m (Schaeffer et al., 2012) (for RCP4.5), • 1.40m (National Research Council, 2012), • 1.65 m (Jevrejeva et al., 2012b) (for RCP8.5), • 1.79 m (Vermeer and Rahmstorf, 2009), • 1.90 m (Rahmstorf et al., 2012b) (with proxy

calibration, for RCP8.5), • 2.25m (Sriver et al., 2012)• 2.4 m (Nicholls et al., 2011)


(Stocker et al., 2013).

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Documents

Review of sea level variability