4/28/2016
5 Billion Years of Earth’s Climate History
Sea Level Changes
• Why Important?
•
•
•
•
•
The dark blue areas indicate periods of continental glaciations or Glacioeustatic
Sea Level Changes
Possible driving forces for
climate and S.L. change:
Time Orders
Eustacy
Recognizing Eustacy?
Glacioeustatic S.L. Change
Geoeustatic S.L. Changes
•Plate Tectonics (location of
continents / ocean currents + long
term changes in SFS rates)
•Greenhouse Gases (anthropogenic
or natural)
•Milankovitch Cycles
Future Estimates of Sea Level Rise
.5 meters / 50cm / 1.64ft
or 5mm/yr
0.2 meters / 20cm / .72ft
or 2mm/yr
Milutan Milankovic, 1879 – 1958
Serbian geophysicist, Civil
Engineer
GLACIOUESTATIC SEA LEVEL CHANGES
These changes in sea level have been occurring for the last
~2.8 MY.
This Epoch of time is called the Pleistocene. Many refer to
the Pleistocene as “The Ice Ages”.
The Pleistocene consists of both “Glacial Maximums” = cold
times, larger polar caps, low stands of sea Level, AND
“Interglacials” = warmer times, less ice and high stands of sea
level.
Some people regard Glacial Maximums & Ice Ages as
Synonyms
We are currently in an Interglacial, a high stand of SL, warmer.
Most of the Pleistocene consisted of Glacial Maximums, colder.
GLACIOUESTATIC SEA LEVEL CHANGES
1. Very important for coastal landforms.
2. They result from advancing and retreating glaciers and the
polar ice caps. A long term climatic puzzle ???
3. There is a change in volume of seawater and ice (polar caps)
4. Last Glacial Maximum was approximately 16,000 to 18,000 years B.P.
Sea level has been rising ever since..........
most places.......
Sea level is still slowly rising in
5. During glacial episodes as much as 50 million cubic kilometers (12 million
cubic miles) of sea water were removed from the oceans and transformed
into glacial ice – sea level dropped 350 – 410 feet.
6. During the last Glacial Maximum sea level was approximately 120
meters lower than today. San Francisco Bay was mostly dry.....
much of Monterey Bay Continental Shelf was exposed......
7. If all the ice in Greenland and Antarctica melted in one week, sea level would
rise approximately 70 meters worldwide.
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4/28/2016
Some Evidence of Climatic Instability and past
Glacioeustatic Sea Level Changes
1.
2.
3.
4.
5.
6.
Glacial Deposits on Continents / Cont. Shelves
Pluvial Lakes
Relic River Sediments
Tidal Gauge Data and Satellite Altimetry
Wave Cut Terraces near shorelines
Carbon Dioxide and Oxygen Isotopes preserved in
Glacial Ice and Planktonic oozes.
7. Seismic Reflection Profiling Continental Shelves......
onlapping and offlapping sediments
8. Estuarine stratigraphy
U-shaped Valley in Alaska
Glacial Grooves at Kellys Island Lake Erie and Manhatten NY
Glacial Events recorded in the Mid-continent
region of North America during the Pleistocene
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•
•
•
•
•
•
Postglacial Age (Holocene)
WISCONSIN STAGE (late Pleistocene)
Sangamon Interglacial Age
ILLINOIAN STAGE
Interglacial Age
KANSAN STAGE
Interglacial Age
• NEBRASKAN STAGE (early Pleistocene)
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4/28/2016
Some Evidence of Climatic Instability and past
Glacioeustatic Sea Level Changes
1.
2.
3.
4.
5.
6.
Glacial Deposits on Continents / Cont. Shelves
Pluvial Lakes
Relic River Sediments
Tidal Gauge Data and Satellite Altimetry
Wave Cut Terraces near shorelines
Carbon Dioxide and Oxygen Isotopes preserved in
Glacial Ice and Planktonic oozes.
7. Seismic Reflection Profiling Continental Shelves......
onlapping and offlapping sediments
8. Estuarine stratigraphy
Some Evidence of Climatic Instability and past
Glacioeustatic Sea Level Changes
Glacial
Maximum
17,000 years
B.P.
1.
2.
3.
4.
5.
6.
Glacial Deposits on Continents / Cont. Shelves
Pluvial Lakes
Relic River Sediments
Tidal Gauge Data and Satellite Altimetry
Wave Cut Terraces near shorelines
Carbon Dioxide and Oxygen Isotopes preserved in
Glacial Ice and Planktonic oozes.
7. Seismic Reflection Profiling Continental Shelves......
onlapping and offlapping sediments
8. Estuarine stratigraphy
Relic River
Deposits
Tidal Gauge Data
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The San Francisco tide station has measured the rise
and fall of tides continuously since June 30, 1854
Some Evidence of Climatic Instability and past
Glacioeustatic Sea Level Changes
San Clemente Island
1.
2.
3.
4.
5.
6.
Glacial Deposits on Continents / Cont. Shelves
Pluvial Lakes
Relic River Sediments
Tidal Gauge Data and Satellite Altimetry
Wave Cut Terraces near shorelines
Carbon Dioxide and Oxygen Isotopes preserved in
Glacial Ice and Planktonic oozes.
7. Seismic Reflection Profiling Continental Shelves......
onlapping and offlapping sediments
8. Estuarine stratigraphy
Greenland Ice Sheet Project 2 (GISP2) Drilling Station
Oxygen naturally
occurs in 3
isotopes:
16O
(99.763%)
17O
(0.0375%)
18O
(0.1995%)
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4/28/2016
Temperature Change for the Past 160,000 years from
the Vostok Ice Core in Eastern Antarctica (3,623m)
Oxygen-18 is decreasing
(proportionately) in the ice
as more O-16 is evaporating
from the world’s oceans
Glacial ice around
the world will have
less O-18
proportional to
O-16 during
glacial maximums
A decrease in 1 part
per million of
Oxygen-18 in glacial
ice reflects a 1.5
degree Celsius drop
in air temperature at
the time the H20
originally evaporated
from the oceans.
1ppm decrease= 1.5 degree C drop
2ppm decrease = 3 degree C drop
3 ppm decrease = 4.5 degree C drop
4ppm decrease = 6 degree C drop
5ppm decrease = 7.5 degree C drop
Planktonic Organisms
Average temperature over past 900,000 years
Cold periods, less O-16, more O-18 in shells
Average surface temperature (°C)
Warm periods, more O-16, less O-18 in shells
17
16
15
Today’s Temperature
14
13
12
11
10
9
900
800
700
600
500
400
300
Thousands of years ago
200
100
Present
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4/28/2016
Today’s sea level
0
0
–130
–426
250,000
200,000
150,000
100,000
Years before present
Some Evidence of Climatic Instability and past
Glacioeustatic Sea Level Changes
Height below present
sea level (feet)
Height above or below
present sea level (meters)
Variations in Earth’s Temperature over the past 850,000
years
50,000
0
Present
Seismic Reflection Profiling
1.
2.
3.
4.
5.
6.
Glacial Deposits on Continents / Cont. Shelves
Pluvial Lakes
Relic River Sediments
Tidal Gauge Data and Satellite Altimetry
Wave Cut Terraces near shorelines
Carbon Dioxide and Oxygen Isotopes preserved in
Glacial Ice and Planktonic oozes.
7. Seismic Reflection Profiling Continental Shelves......
onlapping and offlapping sediments
8. Estuarine stratigraphy
Some Evidence of Climatic Instability and past
Glacioeustatic Sea Level Changes
1.
2.
3.
4.
5.
6.
Glacial Deposits on Continents / Cont. Shelves
Pluvial Lakes
Relic River Sediments
Tidal Gauge Data and Satellite Altimetry
Wave Cut Terraces near shorelines
Carbon Dioxide and Oxygen Isotopes preserved in
Glacial Ice and Planktonic oozes.
7. Seismic Reflection Profiling Continental Shelves......
onlapping and offlapping sediments
8. Estuarine stratigraphy
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4/28/2016
Geouestatic
Sea Level
Changes
@18cm/yr for 20 mill yrs = 3,600km
@4cm/yr for 20 mill yrs = 800km
20
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4/28/2016
Rising Sea Level……….
8