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Further detail and exploration of Eustatic sea level and what influences it.
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{{short description|The distance from the center of the earth to the sea surface}}
{{short description|The distance from the center of the earth to the sea surface}}
The '''eustatic sea level''' is the distance from the center of the earth to the sea surface.<ref name="patzkowskyholland30" /><ref name="schlager92" /> An increase of the eustatic sea level can be generated by decreasing [[glaciation]], slower spreading rates of the [[mid-ocean ridge]]s or fewer mid-oceanic ridges. Conversely increasing glaciation, faster spreading rates or more mid-ocean ridges lead to a fall of the eustatic sea level.
The '''eustatic sea level''' is the distance from the center of the earth to the sea surface.<ref name="patzkowskyholland30"/><ref name="schlager92"/> An increase of the eustatic sea level can be generated by decreasing [[glaciation]], slower spreading rates of the [[mid-ocean ridge]]s or fewer mid-oceanic ridges. Conversely increasing glaciation, faster spreading rates or more mid-ocean ridges lead to a fall of the eustatic sea level.


Changes in the eustatic sea level lead to changes in [[Accommodation (geology)|accommodation]] and therefore affect the deposition of sediments in marine environments.
Changes in the eustatic sea level lead to changes in [[Accommodation (geology)|accommodation]] and therefore affect the deposition of sediments in marine environments.


Eustatic (global) sea level refers to the sea level change of the volume of Earth’s oceans. <ref name="Rovere2015" /> This is not a physical level but instead represents the sea level if all of the water in the oceans were contained in a single basin. <ref name="UniversityColorado2016" /> Eustatic sea level is not relative to local surfaces, because relative sea level is dependent on many factors including tectonics, continental rise and subsidence, and many others. Eustatic sea level follows the ‘Bath Tub Theory’ which describes the ocean as a single bath rub. You can add or remove water and Earth’s oceans will gain or lose water globally.
Eustatic (global) sea level refers to the sea level change of the volume of Earth’s oceans. <ref name="Rovere2015"/> This is not a physical level but instead represents the sea level if all of the water in the oceans were contained in a single basin. <ref name="UniversityColorado2016"/> Eustatic sea level is not relative to local surfaces, because relative sea level is dependent on many factors including tectonics, continental rise and subsidence, and many others. Eustatic sea level follows the ‘Bath Tub Theory’ which describes the ocean as a single bath rub. You can add or remove water and Earth’s oceans will gain or lose water globally.
Differences of Eustatic sea level are caused by 3 main factors:
Differences of Eustatic sea level are caused by 3 main factors:
1. Changes in total ocean water mass (ice sheet runoff)
1. Changes in total ocean water mass (ice sheet runoff)
• When an ice sheet such as Greenland begins to lose its ice mass due to melt, the liquid water is transported to the ocean. <ref name="Ahlstrøm2017" /> According to the ‘bathtub theory’, ice sheet runoff from Greenland will effect Eustatic sea level in all areas of the world whether proximal or distant. <ref name="Rovere2015" />
• When an ice sheet such as Greenland begins to lose its ice mass due to melt, the liquid water is transported to the ocean. <ref name="Ahlstrøm2017"/> According to the ‘bathtub theory’, ice sheet runoff from Greenland will effect Eustatic sea level in all areas of the world whether proximal or distant. <ref name="Rovere2015"/>
• Ocean water mass may also shrink in size if continental ice sheet grow in size, thereby removing liquid water from oceans and converting them to grow ice sheets <ref>Penn State 2018</ref>
• Ocean water mass may also shrink in size if continental ice sheet grow in size, thereby removing liquid water from oceans and converting them to grow ice sheets <ref name="PennState2018">Penn State 2018</ref>
2. Changes in the size of the ocean basin (GIA: glacial isostatic adjustment)
2. Changes in the size of the ocean basin (GIA: glacial isostatic adjustment)
• The ocean basin can gradually grow or shrink from GIA. <ref name="UniversityColorado2016" /> GIA occurs from major glaciations or melts. When a continent experiences mass glaciations, a significant weight is pressed upon the continental crust which ‘floats’ on the upper mantle. This portion of the upper mantle moves like plastic, so the weighted crust will sink. Thus, the ocean basin itself will shrink. Vice versa, when ice sheet runoff occurs, the weight on the crust is relieved causing rise of continental crust <ref="PennState2018" />. This will effectively increase the size of the ocean basin.
• The ocean basin can gradually grow or shrink from GIA. <ref name="UniversityColorado2016"/> GIA occurs from major glaciations or melts. When a continent experiences mass glaciations, a significant weight is pressed upon the continental crust which ‘floats’ on the upper mantle. This portion of the upper mantle moves like plastic, so the weighted crust will sink. Thus, the ocean basin itself will shrink. Vice versa, when ice sheet runoff occurs, the weight on the crust is relieved causing rise of continental crust <ref name="PennState2018"/>. This will effectively increase the size of the ocean basin.
3. Density changes of the water (thermal expansion)
3. Density changes of the water (thermal expansion)
• Greenhouse gases are molecules such as carbon dioxide, methane, ozone, and many others. These gases allow sunlight to penetrate to Earth’s surface, with minimal energy escape. Greenhouse gases are correlated with a positive feedback to surface temperatures.
• Greenhouse gases are molecules such as carbon dioxide, methane, ozone, and many others. These gases allow sunlight to penetrate to Earth’s surface, with minimal energy escape. Greenhouse gases are correlated with a positive feedback to surface temperatures.
• Thermal expansion is affected by the cooling and warming of the ocean basins. This is influenced by climatic fluctuations. <ref name="Rovere2015" /> As greenhouse gases increase in the atmosphere, global warming occurs. This uniform warming will cause water to experience greater molecular motion, thus increasing the volume a molecule will occupy. A decrease in atmospheric greenhouse gases will influence a colder climate. A colder climate will decrease molecular motion, thus water molecules will occupy a lesser space. <ref name="Rovere2015" />
• Thermal expansion is affected by the cooling and warming of the ocean basins. This is influenced by climatic fluctuations. <ref name="Rovere2015"/> As greenhouse gases increase in the atmosphere, global warming occurs. This uniform warming will cause water to experience greater molecular motion, thus increasing the volume a molecule will occupy. A decrease in atmospheric greenhouse gases will influence a colder climate. A colder climate will decrease molecular motion, thus water molecules will occupy a lesser space. <ref name="Rovere2015"/>
• Thermal expansion may also be influenced by ocean salinity. <ref name="Rovere2015" /> As continental ice accumulates, the ocean water freezes onto land but the salt it carried will mostly remain in the ocean. Thus, as ice sheets increase, ocean salinity also increases (and vice-versa). An increase in salinity will increase the density of the ocean basin. Melting of ice sheets and a decrease of ocean salinity will effectively decrease the density of the water.
• Thermal expansion may also be influenced by ocean salinity. <ref name="Rovere2015"/> As continental ice accumulates, the ocean water freezes onto land but the salt it carried will mostly remain in the ocean. Thus, as ice sheets increase, ocean salinity also increases (and vice-versa). An increase in salinity will increase the density of the ocean basin. Melting of ice sheets and a decrease of ocean salinity will effectively decrease the density of the water.


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== References ==
http://sealevel.colorado.edu/faq#n3124
{{reflist
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http://sealevel.colorado.edu/content/what-glacial-isostatic-adjustment-gia-and-why-do-you-correct-it
| colwidth = 25em
| refs =


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<ref name="patzkowskyholland30">{{cite book |last1=Patzkowsky |first1= Mark E. |first2=Steven M. |last2=Holland|year= 2012|title=Stratigraphic Paleobiology |location=Chicago |publisher=University of Chicago University Press|pages=30}}</ref>


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<ref name="schlager92">{{cite book |last1=Schlager |first1= Wolfgang |year= 2005|title=Carbonate Sedimentology and Sequence Stratigraphy |location=Tulsa |publisher=Society for Sedimentary Geology |page=92|isbn=1-56576-116-2 }}</ref>
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== References ==

<references>
⚫
<ref name="Ahlstrøm2017">Ahlstrøm, A. P., Petersen, D., Langen, P. L., Citterio, M., & Box, J. E. (2017). Abrupt shift in the observed runoff from the southwestern Greenland ice sheet. Science Advances,3(12). [http://advances.sciencemag.org/content/3/12/e1701169 doi:10.1126/sciadv.1701169]</ref>
⚫
<ref name="patzkowskyholland30" > {{cite book |last1=Patzkowsky |first1= Mark E. |first2=Steven M. |last2=Holland|year= 2012|title=Stratigraphic Paleobiology |location=Chicago |publisher=University of Chicago University Press|pages=30}} </ref>

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<ref name="schlager92" > {{cite book |last1=Schlager |first1= Wolfgang |year= 2005|title=Carbonate Sedimentology and Sequence Stratigraphy |location=Tulsa |publisher=Society for Sedimentary Geology |page=92|isbn=1-56576-116-2 }} </ref>
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<ref name="Rovere2015">Rovere, A., Stocchi, P., & Vacchi, M. (2016). Eustatic and Relative Sea Level Changes. Current Climate Change Reports,2(4), 221-231. [https://link.springer.com/article/10.1007/s40641-016-0045-7 doi:10.1007/s40641-016-0045-7]</ref>

⚫
<ref name="Ahlstrøm2017" /> {{Ahlstrøm, A. P., Petersen, D., Langen, P. L., Citterio, M., & Box, J. E. (2017). Abrupt shift in the observed runoff from the southwestern Greenland ice sheet. Science Advances,3(12). doi:10.1126/sciadv.1701169}} </ref>
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<ref name="UniversityColorado2016">[http://sealevel.colorado.edu/faq#n3124 CU Sea Level Research Group], [http://sealevel.colorado.edu/content/what-glacial-isostatic-adjustment-gia-and-why-do-you-correct-itCU Sea Level Research Group]</ref>
⚫
<ref name="Rovere2015" /> {{Rovere, A., Stocchi, P., & Vacchi, M. (2016). Eustatic and Relative Sea Level Changes. Current Climate Change Reports,2(4), 221-231. doi:10.1007/s40641-016-0045-7}} </ref>
<ref name="UniversityColorado2016" /> {{CU Sea Level Research Group. (2016). Retrieved from http://sealevel.colorado.edu/faq#n3124}} </ref>
<ref name="UniversityColorado2016" /> {{CU Sea Level Research Group. (2016). Retrieved from http://sealevel.colorado.edu/content/what-glacial-isostatic-adjustment-gia-and-why-do-you-correct-it}} </ref>
⚫
<ref="PennState2018" /> {{Cornell, S., Fitzgerald, D., Frey, N., Georgiou, I., Hanegan, K., Hung, L., . . . Yarnal, B. (n.d.). (2018). Isostatic Changes – Glacial Isostatic Adjustment. Retrieved from https://www.e-education.psu.edu/earth107/node/1501}} </ref>


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<ref="PennState2018">{{Cornell, S., Fitzgerald, D., Frey, N., Georgiou, I., Hanegan, K., Hung, L., . . . Yarnal, B. (n.d.). (2018). Isostatic Changes – Glacial Isostatic Adjustment. Retrieved from https://www.e-education.psu.edu/earth107/node/1501}}</ref>
</references>
}}


[[Category:Sea level]]
[[Category:Sea level]]

Revision as of 02:36, 11 December 2018

The eustatic sea level is the distance from the center of the earth to the sea surface.[1][2] An increase of the eustatic sea level can be generated by decreasing glaciation, slower spreading rates of the mid-ocean ridges or fewer mid-oceanic ridges. Conversely increasing glaciation, faster spreading rates or more mid-ocean ridges lead to a fall of the eustatic sea level.

Changes in the eustatic sea level lead to changes in accommodation and therefore affect the deposition of sediments in marine environments.

Eustatic (global) sea level refers to the sea level change of the volume of Earth’s oceans. [3] This is not a physical level but instead represents the sea level if all of the water in the oceans were contained in a single basin. [4] Eustatic sea level is not relative to local surfaces, because relative sea level is dependent on many factors including tectonics, continental rise and subsidence, and many others. Eustatic sea level follows the ‘Bath Tub Theory’ which describes the ocean as a single bath rub. You can add or remove water and Earth’s oceans will gain or lose water globally. Differences of Eustatic sea level are caused by 3 main factors: 1. Changes in total ocean water mass (ice sheet runoff) • When an ice sheet such as Greenland begins to lose its ice mass due to melt, the liquid water is transported to the ocean. [5] According to the ‘bathtub theory’, ice sheet runoff from Greenland will effect Eustatic sea level in all areas of the world whether proximal or distant. [3] • Ocean water mass may also shrink in size if continental ice sheet grow in size, thereby removing liquid water from oceans and converting them to grow ice sheets [6] 2. Changes in the size of the ocean basin (GIA: glacial isostatic adjustment) • The ocean basin can gradually grow or shrink from GIA. [4] GIA occurs from major glaciations or melts. When a continent experiences mass glaciations, a significant weight is pressed upon the continental crust which ‘floats’ on the upper mantle. This portion of the upper mantle moves like plastic, so the weighted crust will sink. Thus, the ocean basin itself will shrink. Vice versa, when ice sheet runoff occurs, the weight on the crust is relieved causing rise of continental crust [6]. This will effectively increase the size of the ocean basin. 3. Density changes of the water (thermal expansion) • Greenhouse gases are molecules such as carbon dioxide, methane, ozone, and many others. These gases allow sunlight to penetrate to Earth’s surface, with minimal energy escape. Greenhouse gases are correlated with a positive feedback to surface temperatures. • Thermal expansion is affected by the cooling and warming of the ocean basins. This is influenced by climatic fluctuations. [3] As greenhouse gases increase in the atmosphere, global warming occurs. This uniform warming will cause water to experience greater molecular motion, thus increasing the volume a molecule will occupy. A decrease in atmospheric greenhouse gases will influence a colder climate. A colder climate will decrease molecular motion, thus water molecules will occupy a lesser space. [3] • Thermal expansion may also be influenced by ocean salinity. [3] As continental ice accumulates, the ocean water freezes onto land but the salt it carried will mostly remain in the ocean. Thus, as ice sheets increase, ocean salinity also increases (and vice-versa). An increase in salinity will increase the density of the ocean basin. Melting of ice sheets and a decrease of ocean salinity will effectively decrease the density of the water.

References

  1. ^ Patzkowsky, Mark E.; Holland, Steven M. (2012). Stratigraphic Paleobiology. Chicago: University of Chicago University Press. p. 30.
  2. ^ Schlager, Wolfgang (2005). Carbonate Sedimentology and Sequence Stratigraphy. Tulsa: Society for Sedimentary Geology. p. 92. ISBN 1-56576-116-2.
  3. ^ a b c d e Rovere, A., Stocchi, P., & Vacchi, M. (2016). Eustatic and Relative Sea Level Changes. Current Climate Change Reports,2(4), 221-231. doi:10.1007/s40641-016-0045-7
  4. ^ a b CU Sea Level Research Group, Sea Level Research Group
  5. ^ Ahlstrøm, A. P., Petersen, D., Langen, P. L., Citterio, M., & Box, J. E. (2017). Abrupt shift in the observed runoff from the southwestern Greenland ice sheet. Science Advances,3(12). doi:10.1126/sciadv.1701169
  6. ^ a b Penn State 2018
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