POTENTIAL GLOBAL WARMING AND SEA
LEVEL RISE
LOAY GHAZALEH, MBA, BSC. CIVIL ENG.
BAHRAIN
APRIL, 2017

CLIMATE CHANGE
CLIMATE CHANGE AND SEA LEVEL RISE
SEA LEVEL RISEPREDICTIONS
EFFECTS OF SEA-LEVEL RISE
COASTAL IMPACTS OF SEA LEVEL RISE
TIDAL GAUGES & SATELLITE ALTIMETRY

CLIMATE CHANGE
Since the early 20th century,
temperature increased by 0.8 °C

PREVIEW
 Global warming is the rise in the average temperature of Earth's
atmosphere and oceans since the late 19th century and its projected
continuation.
 Since the early 20th century, Earth's mean surface temperature
has increased by about 0.8 °C (1.4 °F), with about two-thirds of
the increase occurring since 1980.
 Warming is believed to be caused by increasing concentrations of
greenhouse gases produced by human activities such as the burning of
fossil fuels and deforestation.
 The effects of an increase in global temperature include a rise in sea levels
and a change in the amount and pattern of precipitation, as well a
probable expansion of subtropical deserts.
 Other likely effects of the warming include a more frequent
occurrence of extreme-weather events including heat waves,
droughts and heavy rainfall, ocean acidification and species
extinctions due to shifting temperature regimes.
 Effects significant to humans include the threat to food security from
decreasing crop yields and the loss of habitat from inundation.

Where do WE come into this?
Burning Fossil Fuels Deforestation Agriculture
MOO!
By burning fossil fuels, cutting down entire forests and even
breeding cows, we are polluting our atmosphere.
By burning fossil fuels for
energy such as coal, oil
and gas, we are releasing
extra CO2 into the
atmosphere.
Trees use CO2 in the
atmosphere for
photosynthesis but
some trees are cut
down for agricultural
purposes.
We breed many cows
for milk and meat,
but when cows are
„windy‟… they release
methane methane!

The Greenhouse Effect
 Infrared (IR) active gases, principally water vapor (H2O),
carbon dioxide (CO2) and ozone (O3), naturally present in the
Earth‟s atmosphere, absorb thermal IR radiation emitted by
the Earth‟s surface and atmosphere.
 The atmosphere is warmed by this mechanism and, in
turn, emits IR radiation, with a significant portion of
this energy acting to warm the surface and the lower
atmosphere.
 As a consequence the average surface air temperature of the
Earth is about 30° C higher than it would be without
atmospheric absorption and re-radiation of IR energy.
 This phenomenon is popularly known as the greenhouse effect,
and the IR active gases responsible for the effect are likewise
referred to as greenhouse gases.
 Adding millions of tons of greenhouse gasses to the
atmosphere makes the greenhouse effect „too efficient‟,
causing climate change.

Incoming Solar
Radiation 343 W/m2
Reflected Solar
Radiation 103 W/m2
Long-wave Radiation
240 W/m
2
CO2 CH4,
N2O, O3,
Water
vapour,
aerosols,
clouds
Earth’s ground temperature, approx 13o
C with greenhouse
effect, approx - 20o
C without it. Doubling CO2 increases
temperature by between 1.5o
C and 4o
C.
The Greenhouse Effect
“Blanket” of Greenhouse Gases
The Green House Effect
The principal
greenhouse gas
concentrations
that have
increased over
the industrial
period are carbon
dioxide (CO2),
methane (CH4),
nitrous oxide
(N2O), and
chlorofluorocarbo
ns (CFCs).

Ozone Layer Depletion and Climate Change
 The ozone layer absorbs harmful ultraviolet-B radiation
from the sun. Over the past 30 years ozone levels over
parts of Antarctica have dropped by almost 40% during
some months and a 'hole' in ozone concentrations is
clearly visible in satellite observations.
 Ozone is been damaged mainly by:
1. Chlorofluorocarbons (CFCs) that are used in
refrigerators, aerosols, and as cleaners in
many industries.
2. Halons that are used in fire extinguishers.
3. Aircraft emissions of nitrogen oxides and
water vapour.
 As Ozone is considered to be a greenhouse gas, a depleted
ozone layer may partially dampen the greenhouse effect.
 Conversely, efforts to tackle ozone depletion may
result in increased global warming!

Climate Change vs Accelerating
Climate change
According to NASA, the rate
of change is TEN times
faster than the Earth‟s
usual rate of recovery to
warmer temperatures after
an ice age.
The IPCC project that the
average global temperature
will probably rise more than
2 degrees Celsius in the
next 100 years.

The Melting Snows
Mt Kilimanjaro
Summer 1979
Summer 2003
Arctic Sea

Seasonal variation in Arctic sea ice
(2014)
March
maximum
September
minimum
Murmansk

Projected Global Temperature
Change

-3 -2.5-1.5 -1 -.5 -.1 .1 .5 1 1.5 2.5 3.4
2005 Temperature Changes
Compared to 1951-1980

CLIMATE CHANGE AND SEA LEVEL RISE
Most records show a gradual rise in
mean sea level over last century.

Terrestrial water storage,
Extraction of groundwater,
Building reservoirs Subsidence in river
delta, Land
movements,
Tectonic
displacements
Seepage into aquifers
Circulation changes,
Storm surges,
Water expands as it
warms
Exchange of ocean
water With glaciers
and ice sheets
Causes of Sea Level Change

CLIMATE CHANGE AND SEA LEVEL RISE
 Sea-level rise due to global warming occurs primarily
because water expands as it warms up.
 The melting ice caps and mountain glaciers also add
water to the oceans, thus rising the sea level.
 The contribution from large ice masses in Greenland
and Antarctica is expected to be small over the
coming decades. But it may become larger in future
centuries.
 Changes in land-levels due to coastal subsidence or
geological movements can also affect local sea-levels.
 Sea-level rise can be offset up by irrigation, the
storage of water in reservoirs, and other land
management practices that reduce run-off of water
into the oceans.

Sea-level rise: Historic changes
 Since the Last Glacial Maximum (~20,000 years BP)
MSL has risen by over 120 m at locations far
from present and former ice sheets.
 Between 15,000 and 6,000 years ago MSL rose
rapidly at an average rate of 10 mm/yr.
 Following last glacial period local vertical land
movements are still occurring today as a result of
large transfers of mass from the ice sheets to the
ocean.
 During the last 6,000 years, global MSL
variations on time-scales of a few hundred
years and longer are likely to have been less
than 0.3 to 0.5 m

Climate Change and Sea Level
Rise During the 20th Century
 During the 20th century, tide gauge data shows MSL rises
in the range 1.0 to 2.0 mm/yr (more than during 19th
century)
 Between 1870 and 2004, global average sea levels rose
195 mm (7.7 in).
 From 1950 to 2009, measurements show an average annual
rise in sea level of 1.7 ± 0.3 mm per year, with satellite data
showing a rise of 3.3 ± 0.4 mm per year from 1993 to 2009,
a faster rate of increase than previously estimated.
 The most recent estimate during the 20th century is 1.4 -
2.0 mm/yr, with a central value of 1.7 ± 0.3 mm/yr.
 The IPCC has estimated that, if the emission of
greenhouse gases continues at the current rate, the level
of the sea surface will rise by an additional 8-20 cm by
2030, 21-71 cm by 2070 and 31-110 cm by 2100.

Causes Of SEA LEVEL RISE
 This significant rate of rise in sea level is attributed to global
warming caused by industrialization during the second half of
the 19th century.
 There is decadal variability in extreme sea levels but no
evidence of widespread increases in extremes other than that
associated with a change in the mean sea level. Most records show
evidence of a gradual rise in global mean sea level over the
last century.
 land movements (e.g. uplift or submergence) can mask this
signal due to actual changes in sea level.
 PRIMARY CAUSES OF Sea Level Rise;
 Thermal expansion: as ocean water warms, it expands.
 The contribution of land-based ice due to increased
melting. The major store of water on land is found in
glaciers , polar ice caps and (Greenland and West
Antarctica)

THE PROSPECT OF SATELLITE
ALTIMETRY IN SEA LEVEL STUDIES
 Satellite altimetry provides near-global coverage of the
world‟s oceans and thus the promise of determining the
global-averaged sea level rise, its regional variations,
and changes in the rate of rise more accurately and
quickly than is possible from the sparse array of in situ
gauges.
 TOPEX/Poseidon satellite altimeter missions with its
(near) global coverage from 66°N to 66°S was launched
in August 1992. Estimates of the rates of rise from the
short T/P record are 2.5 ± 1.3 mm/ yr over the 6-yr
period 1993–98 (Church et al, 2004).
 Using a combination of tide gauge records and satellite
altimetry, Jevrejeva et al. (2006) have estimated this
rate to be 2.4 mm/yr over the same period.

SEA LEVEL RISE
Between 1870 and 2004, global
average sea level rose 195 mm

RELATIVE SEA LEVEL CHANGE
 The local change in sea level at any coastal location as measured by a
tide gauge depends on the sum of global, regional and local factors
and is termed relative sea-level change.
 It is so called “RELATIVE” because it is affected by either by
movement of the land on which the tide gauge is situated or by the
change in the height of the adjacent sea surface.
 Most of the tide gauges are located in mid-latitude northern
hemisphere, few in middle of oceans, and contaminated by earth
movements.
 The main source for the uncertainties in using tide gauge records still
remain: poor historical distribution of tide gauges, lack of data from
Africa and Antarctica, and localized tectonic activity.
 Relative Sea Level (height above a local datum) depends on:
 Global Mean Sea Level
 Regional Variability
 Vertical Land Movement (uplift/subsidence)

Sources of sea level rise: 1993 -
2003

Average Rate of Sea Level Rise (mm) and Estimated
Contributions from Different Processes: 1910 - 1990
Factor Min Mid value Max
Ocean thermal expansion 0.3 0.5 0.7
Glaciers and ice caps 0.2 0.3 0.4
Greenland – 20th
Century effects 0 0.05 0.1
Antarctica – 20th
Century effects -0.2 -0.1 0
Ice sheets – Adjustment since LGM 0 0.25 0.5
Permafrost 0 0.025 0.05
Sediment deposition 0 0.025 0.05
Terrestrial storage -1.1 -0.35 0.4
Total -0.8 0.7 2.2
Estimated from tide gauge records
mm)
1 1.5 2

How fast are sea levels rising?

Trends in sea level rise

Past and Projected Changes in
Global Sea Level

Predictions OF Sea Level Rise
 In 2007, the Intergovernmental Panel on Climate
Change (IPCC) projected that during the 21st
century, sea level will rise another 18 to 59 cm (7.1
to 23 in), but these numbers do not include
"uncertainties in climate-carbon cycle
feedbacks nor do they include the full effects
of changes in ice sheet flow".
 On the timescale of centuries to millennia, the
melting of ice sheets could result in even higher sea
level rise. Partial de-glaciation of the Greenland ice
sheet, and possibly the West Antarctic ice sheet,
could contribute 4 to 6 m (13 to 20 ft) or more
to sea level rise.

Projections of the future

EFFECTS OF SEA-LEVEL RISE
Vulnerable populated regions,
Populations >8 million

Vulnerable populated regions,
Populations >8 million

Effects of sea-level rise
 Increased coastal erosion,
 Higher storm-surge flooding,
 More extensive coastal inundation,
 Changes in surface water quality and groundwater
characteristics,
 Increased loss of property and coastal habitats,
 Increased flood risk and potential loss of life,
 Loss of non-monetary cultural resources and values,
 Impacts on agriculture and aquaculture through
decline in soil and water quality, and loss of tourism,
recreation, and transportation functions.
Sea-level rise potentially affects human populations
(e.g., those living in coastal regions and on islands) and
the natural environment (e.g., marine ecosystems).

Storm Surges and Extreme Events
We might complain when it‟s
raining, but, in the South Pacific,
rising sea levels bring an increased
risk of storm surges.
Storm surges are a threat to
the people who live by the
coast. They can destroy homes,
crops and water supplies. Along
with sea level rise, they could
make islands uninhabitable.
“The weather forecast for today is cloudy with a good chance of
a cyclone induced storm surge”. Best bring an umbrella then eh?

Stronger Hurricanes
 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 102-200% for sea level rise
greater than 90 cm
 Tropical cyclones to shift towards strong storms (2-11%
intensity increase by 2100)
 Decrease in global frequency of tropical cyclones (6-34%)
 Increase in rainfall rate, 20% within 100 km of storm
center
Andrew (1992)
$26.5 billion

Ocean Acidification
Some of the excess CO2 in the atmosphere is also
being dissolved into the ocean. This is causing
the water to become more acidic.
This is bad news for marine
ecosystems, especially to coral
reefs, fish, marine mammals and
other animals who call the ocean
their home. It is also bad news for
those who rely on fishing for their
businesses or as a source of food.

Health and Disease
It might not be obvious, but
climate change can cause people
to get sick, and not just from
injury or drowning.
• Malnutrition- Storms and rising sea
levels can destroy food sources.
• Sickness and Diarrhoea - Often the
islands only have only one source of
fresh water, and storms can often
cause this supply to be
contaminated.

Climate Change and
Environmental Issues

Climate Change and Food

Other Effects
• The climate in some areas will become unsuitable for some
animal and plant species, causing mass migration or
population declines e.g. Polar bears in the Arctic
• Some species will be able to live in places that they never
could before. This means that many places will see an increase
in alien species (and that doesn't mean little green men!)
The impacts of climate
change are numerous and
will affect all sorts of plant
and animal species.

COASTAL IMPACTS OF SEA LEVEL RISE
Saltwater intrusion, Flooding,
erosion, displacement of wetlands

PHYSICAL IMPACTS OF SEA LEVEL RISE
PRIMARY IMPACTS
 Inundation and displacement of wetlands and lowlands
 Increased vulnerability to coastal storm damage and
flooding
 Shoreline erosion
 Saltwater intrusion into estuaries and freshwater aquifers
SECONDARY IMPACTS
 Altered tidal ranges in rivers and bays
 Changes in sedimentation patterns
 Decreased light penetration to benthic organisms
 Increase in the heights of waves

Inundation and displacement of
wetlands and lowlands
 This, the most obvious impact of sea
level rise, refers both to the
conversion of dry land to wetland and
the conversion of wetlands to open
water.
 In salt marsh and mangrove habitats,
rapid sea-level rise would submerge
land, waterlog soils, and cause plant
death from salt stress.

Increased vulnerability to coastal
storm damage and flooding
 Sea level rise would increase the impact of tropical
cyclones and other storms that drive storm surges.
 The effects would be disastrous on small island
States and other low-lying developing
countries, such as the Maldives, where 90 per cent
of the population lives along the coast.
 Flooding due to storm surges will increase under
conditions of higher sea level. As is true at present,
damage due to flooding will be most severe when
the surges strike during high tide.

Shoreline erosion
 While acknowledging that erosion is also caused by
many other factors, as sea level rises, the upper
part of the beach is eroded and deposited just
offshore in a fashion that restores the shape of
the beach profile with respect to sea level.
 A rise in sea level immediately results in shoreline
retreat due to inundation. However, a 1 m rise in
sea level implies that the offshore bottom must
also rise 1 m. The sand required to raise the bottom
can be supplied by beach nourishment. Otherwise
waves will erode the necessary sand from the upper
part of the beach.
 1 cm rise in MSL erodes approx 1m horizontally
of beach

Saltwater intrusion into estuaries
and freshwater aquifers
 Sea level rise would generally enable saltwater to advance
inland in both aquifers and estuaries. In estuaries, the gradual
flow of freshwater toward the oceans is the only factor
preventing the estuary from having the same salinity as the
ocean.
 A rise in sea level would increase salinity in open bays because
the increased the cross-sectional area would slow the average
speed at which freshwater flows to the ocean.
 The impact of sea level rise on groundwater salinity could
make some areas uninhabitable even before they were actually
inundated, particularly those that rely on unconfined aquifers
just above sea level.
 As sea level rises, the depth of the freshwater lens in the
coastal zone is greatly reduced, leading to salinization of water
supplies. In extreme cases exacerbated by over-pumping, the
aquifer may rapidly become unsuitable for drinking and even
for irrigation.

Saltwater Intrusion
• 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

Altered tidal ranges in rivers and bays
 Sea level rise could change tidal ranges by:
o Removing barriers to tidal currents
o Changing the resonance frequencies of tidal
basins.
 Greater tidal currents would tend to form larger ebb tidal
deltas, providing a sink for sand washing along the shore and
thereby causing additional erosion.
 Some of the bathymetric changes that might amplify tides
would have the same impact on storm surges.
 higher tidal ranges would further increase the salinity
in estuaries due to increased tidal mixing.

Changes in sedimentation patterns
 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
 Under natural conditions, most of the sediment washing down
rivers is deposited in the estuary due to settling and
flocculation.
 Flocculation is a process by which salty water induces easily
entrained fine-grained sediment to coalesce into larger globs
that settle out. A rise in sea level would cause both of these
processes to migrate upstream.

Decreased light penetration to benthic
organisms
 If sea levels were to rise at a pace faster than
corals could build their reefs upward, eventually
light conditions would be too low for the to
continue photosynthesis.
 On reefs near low-lying coastal areas, sea-level
rise would likely increase coastal erosion
rates, thus degrading water quality and
decreasing light penetration, thus reducing
the depth to which reefs can grow.
 Losses of coral reefs would mean losses in the
high biodiversity of these systems as well as
the fisheries and recreational opportunities they
provide.

Increase in the heights of waves
 In shallow areas, the depth of the water itself limits the
size of waves, which could be the most important impact of
sea level rise along shallow tidal shores with steep, muddy
shores.
 The steep slopes imply that inundation would not be a
problem. However, with water depths one meter
deeper, waves could form large enough to
significantly erode the muddy shores.
 Bigger waves could also increase the vulnerability of lands
protected by coral reefs. In many areas, these reefs
protect mangrove swamps or sandy islands from the direct
attach by ocean waves; but deeper water would reduce
the reef’s ability to act as a breakwater.
 The extent to which this will happen would depend on the
ability of the corals to keep pace with sea level rise.

RESPONSE STRATEGIES
 There are three response strategies to rising sea level and its physical
impacts: RETREAT, ADAPT or DEFEND. In practice, many responses
may be hybrid and combined elements of more than one approach.
 Retreat can involve chaotic abandonment of property and cultural
investments, or it can be an ordered, planned program that minimizes
losses from rising sea level and maximizes the cost-effectiveness of
the operation.
The operation also seeks to leave surrendered areas as aesthetic
looking as possible and to avoid abandoned structures that are an
operational hazard to other social and economic activities.
 Adaptation/Accommodation – all natural system effects are
allowed to occur and human impacts are minimized by adjusting
human use of the coastal zone. For East African countries, adaptation
is the immediate priority to respond to sea-level rise.
 Defence/Protection – natural system effects are controlled by soft
or hard engineering, reducing human impacts in the zone that would
be impacted without protection.

Challenges
 The assessment of impacts of sea level rise over the
next century is hindered by lack of knowledge of
the detailed topography of the near shore.
 New global elevation maps based on detailed
surveys at cm resolution will make it possible to
accurately determine the areas which will be inundated
by storm surges under conditions of rising sea level.
 This will require a concerted effort by the satellite
altimetry community as well as local ground-based
geodetic surveyors in all coastal areas world-wide.

TIDAL GAUGES / STATIONS & SATELLITE
ALTIMETRY IN MSL STUDIES
Mean Sea Level Rise, 1870-2000:
~1.7 mm/yr, on the rise

GLOSSARY
 Bathymetry : The measurement of the depth of large
bodies of water.
 Geoid : A surface of constant gravitational potential that
would represent the sea surface if the oceans were not in
motion.
 Geoid: The equipotential surface of the Earth's gravity
field which best fits, global mean sea level (MSL)
 Satellite altimeter : A space-based ranging technique,
which usually analyzes laser or radar pulses reflected off
of the surface of a planet. When combined with precise
orbit determination of the satellite, these ranging's can be
used to determine ocean, ice, and land surface
topography. The height of the sea level accuracy is 2 cm.
 Tide gauge: An instrument for measuring the rise and fall
of the tide (water level).
54

Model of the shape of the Earth
55

The height of the Earth surface
56

by definition: Mean Sea Level = 0
m = equilibrium level
57
A change in volume of
seawater in one ocean will
affect the level in all others.
Any such world-wide change
in sea-level is called
EUSTATIC SEA-LEVEL
change

Sea Level Datum

Tide Gauges

Monitoring Stations

Sea Level Stations as of February
2000
61

Satellite altimetry
 TOPEX / Poseidon: 1992 - 2005
 Jason-1 &2 : 2001 - present
Ocean Altimetry
 Deep ocean
couldn‟t be
measured until
about 25 years
ago.
 Satellites now
measure
elevation using
altimetry.
 Sea level
determined by
comparing
measured height
and GPS data

JASON-2
satellite GPS
Range
Altimeter
Microwave radiometer
measuring water vapor
Ellipsoid
Satellite
altitude Sea surface
height
Measuring Global Sea Level

Measuring sea level
64

THE PROSPECT OF SATELLITE ALTIMETRY
IN MEAN SEA LEVEL STUDIES
 Analysis of TOPEX/Poseidon satellite altimeter data has
demonstrated that meaningful estimates of global averaged
mean sea level change can be made over much shorter periods
than possible with tide gauges because the global satellite data
account for horizontal displacements of ocean mass.
 However, achieving the required sub-millimeter
accuracy is demanding and requires satellite orbit
information, geophysical and environmental corrections
and altimeter range measurements of the highest
accuracy. It also requires continuous satellite operations
over many years and careful control of biases.

Mean Sea Level Rise, 1870-2000:
~1.7 mm/yr, on the rise
Church et al., 2004, 2006
Holgate and Woodworth, 2004
1.8 +/- 0.3 mm/yr (1960 to 2000)
Satellite altimetry

•Sea Level Rise is spatially, highly non-uniform
GLOSS Tide Gauges
Sea Level Rise From Topex &
Jason-1: 1993-2007

Distribution of sea level (in mm/yr)
from TOPEX/POSEIDON altimetry
68
Yellow and red colors correspond to sea level rise, while blue color corresponds to sea level drop.

Sea Level Change in the last 10 yr
(from Satellites)
69

Reconstruction of MSL using all
data sources
70

SOME GIS / Spatial Data
Developers

72
Loay Ghazaleh, MBA, BSc. Civil Eng.
loay.ghz@gmail.com, +973-36711547
Advisor, Undersecretary Office,
Ministry of Works, Bahrain