IUBAT- International University Of
Business Agriculture And Technology
Submitted By
sumiya kuntula shithy
I’d no: 20109055
sec:A
IMPACTS OF SEA LEVEL RISE

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.

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

Greenhouse Effect
Greenhouse Effect
Sun

The Greenhouse Effect
The rapid
increase in
concentrations
of greenhouse
gases since
the industrial
period began
has given rise
to concern
over potential
resultant
climate
changes

Greenhouse Gases and Global Climate Change
 The principal greenhouse gas concentrations that
have increased over the industrial period are carbon
dioxide (CO2), methane (CH4), nitrous oxide (N2O),
and chlorofluorocarbons (CFCs).
 The observed increase of CO2 in the atmosphere
from about 280 ppm in the pre-industrial era to
about 364 ppm in 1997 has come largely from fossil
fuel combustion and cement production.
 Of the several anthropogenic greenhouse gases,
CO2 is the most important agent of potential future
climate warming because of its large current
greenhouse forcing, its substantial projected future
forcing, and its long persistence in the atmosphere.

-0.6
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
1880 1900 1920 1940 1960 1980 2000
Year
D
Mean
Temperature
(°C)
Recorded Worldwide Temperatures

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

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. This
may therefore lead to increased global warming.
 Conversely, efforts to tackle ozone depletion may result in
increased global warming!

The Melting Snows of Mt Kilimanjaro

RELATIVE SEA LEVEL CHANGE
 Sea level varies as a result of processes operating on a great range of
time-scales, from seconds to millions of years, so that current sea level
change is also related to past climate 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 because it can come about 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.
 Relative sea levels are also measured by dating buried coastal vegetation
(salt marshes, mangroves, etc.).
 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, the GIA corrections used, and localized tectonic activity.

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.
 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. Changes in land-levels due to coastal
subsidence or geological movements can also affect
local sea-levels.

CLIMATE CHANGE AND SEA LEVEL RISE
 About 20,000 years ago during the LGM, large ice sheets
melted causing a rise in sea level of about 100m, most of
the melting occurred about 6,000 years ago.
 Over the past 1,000 years and prior to the 20th century,
the average global sea level rise was of the order of 0.2
mm/yr.
 The rate of sea level rise climbed to about 1-2 mm/yr
during the 20th century, with a central value of 1.5 mm/yr
(IPCC TAR). 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 (Church & White, 2006).
 This significant rate of rise in sea level is attributed to
global warming caused by industrialization during the
second half of the 19th century.

CLIMATE CHANGE AND SEA LEVEL RISE
 There is no evidence for any acceleration of sea level rise
in data from the 20th century data alone. Mediterranean
records show decelerations and even decreases in sea
level in the latter part of the 20th century.
 Most records show evidence of a gradual rise in global
mean sea level over the last century. However, signals
caused by land movements (e.g. uplift or submergence)
can mask this signal due to actual changes in sea level.
 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.

Global Sea Level Change Over the
Last 140,000 Years (IPCC TAR)

Mean Sea Level Variations at Selected
Locations [Data: www.pol.ac.uk/psmsl]

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 dryland 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.

Objective
 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.