This document discusses sea level processes and changes. It aims to provide an understanding of mean sea level, the factors that influence sea level changes, and measurements of sea level change. Key points covered include the difference between geoids and ellipsoids, processes that control mean sea level and cause its changes over various timescales, measuring sea level using tide gauges and satellite altimetry, sea level rise in the last century linked to global warming, and the economic implications of sea level changes. Graphs and tables are presented showing records of sea level change from tide gauge stations over the last century.

1. 1
Presented by:-
Ulagadde R.P.
Dept.Of Applied Geology (M.sc.Part-Ii] School Of
Earth Science Solapur University, Solapur
Seminar on
Sea level processes & changes

2. 2

3. 3

4. 4
Learning Objectives
The shape of the planet: difference between Geoids and
Ellipsoid
The concept of Mean Sea Level
Processes that control the Mean Sea Level and its changes
Sea level changes over millions of year
Measuring sea level (tide gauges, altimetry, δ18
)
Sea level rise in the last century and global warming
Economic implications of Sea level changes

5. 5
Gravitational field effects on sea level

6. Sea Level Variation
Astronomical Tidal Forces
Earth’s water closest to the moon is acted on more strongly by the
moon’s gravity
The solid Earth is pulled harder than the water on the side opposite
the moon
The Sun produces similar tidal forces and accounts for about 1/3 of
ocean tides

7. 7
What does it mean to be at an altitude
of 4000 m?
It mean that I am 4000 m above the
Mean Sea Level (MSL)

8. Causes of Sea Level Change
Terrestrial water storage,Terrestrial water storage,
Extraction of groundwater,Extraction of groundwater,
Building reservoirsBuilding reservoirs
Subsidence in river delta,Subsidence in river delta,
Land movements,Land movements,
Tectonic displacementsTectonic displacements
Seepage into aquifersSeepage into aquifers
Circulation changes,Circulation changes,
Storm surges,Storm surges,
Water expands as it warmsWater expands as it warms
Exchange of ocean waterExchange of ocean water
withwith
glaciers and ice sheetsglaciers and ice sheets

9. 9

10. 10
by definition:
Mean Sea Level = 0 m = equilibrium level
 Changes in volume of water
 Changes in shape and volume of ocean basins
Changes are measured as relative changes to a
reference datum
This reference datum can be a fixed one (e.g.
distance from the center of the earth) or local
(coastline).

11. 11
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

12. 12

13. 13

14. 14

15. 15
Sea Level Change

16. 16
Other effects of plate tectonics
e.g. Upper Cretaceous (90 Ma) MSL > 300 m

17. 17
Summary of spatial-temporal scale of
processes contributing to Mean Sea Level
TIME (years)
∆MSL(meters)
100 1000 100 Ka 10 Ma 100 Ma
1 cm
1 m
10 m
100 m
1 day
(A) Exchange of water with continents (Groundwater, Lakes, etc.)
(B) Temperature expansion
(D) Plate Tectonics(C) Melting of ICE
• Thickness and area of continental crust
• Thermal state of crust
• Load on oceanic by land mass and sediments
(can generate localized changes in MSL,
e.g. subsidence of North Sea )
A,B,C  change in volume of water
D  change in shape of container
NOTE:

18. 18
Sea Level Change in the last 100 yr (from Tidal Gauges)
Tides
Atmospheric
Pressure
+
=
Observations
of Sea Level
Res. Curve = Obs. – Tides - Atmos. Press.

19. WOCE Sea Level Stations as of February 2000 (from Tidal Gauges)

20. 20
Arica
Iquique
Coquimbo
6/23/2001 6/24/2001
What can we say about these
tide gauges record?

21. 21
The Earth's climate has warmed about 1°C (1.8°F) during the last 100 years.
(the warming follows the Little Ice Age (19th
century)  1-2 mm/yr sea level rise)
reduction in volume of ice caps, ice fields,
and mountain glaciers
thermal expansion of ocean water
Increase in greenhouse-gas emissions:
 Global Warming  expansion of oceans
 many of the world's mountain glaciers will disappear
 sea level rise acceleration
IMPACTS of HUMAN on SEA LEVEL:
Numerical models of the Climate System
can be used to predict future changes in Sea Level
FUTURE:

22. 22

23. 23
Thank You……