Environmental Science · Science

Ocean Formation

Introduction

The ocean covers about 71 % of the Earth’s surface (NOAA, 2014). This enormous area of water is formed due to some geological processes in the initial stage of the Earth formation. We have to study Earth composition to understand how land masses rose and what the ocean floor is. Some geological processes such as continental draft and plate tectonics can be considered the cause of the formation of the ocean basin and some oceanic features. In task 2, I discuss the effect of climate change is crucial to determine sea levels. In order to protect the marine environment and control, global warming several strategies are addressed and data evaluated.

Emergence of Oceans

Earth was formed 4.5 Ma years ago from gases resulted from the big bang (Friedl, 2013). 3.8 billion years ago, oceans started to form (Krebs, Sawrey, Trogler, Sailor, Kummel, &Thiemens). There are two hypotheses on how and when oceans had formed. One is said to be by outgassing. Gases are released from molten rocks in the mantle to the atmosphere by volcanic activities. These gases are methane, ammonia, water vapor, and carbon dioxide. After cooling of the earth surface, at approximately 3.8 billion years ago, water condenses into precipitation (McLamb, 2011). The proof of the hypothesis can be found in the fossils dated from Precambrian Era as blue-green algae are found. Another fossil records of Edicaran Period (635 million to 542 million years ago) show the evidence of early marine algae and invertebrates.The other one is by bombardment of comets and meteorites that might have frozen water. Personally, I do not believe in this hypothesis. I cannot find any evidence on how water had delivered to Earth by comets and meteorites.

Earth composition

Earth layers are classified according to density into three primary layers; crust, mantle, and core. The core is the center of the Earth. It divides into two layers; an inner core that is solid iron surrounded by a liquid outer core. Mantle is a layer that lies above the core. It is a thick rocky layer composed of several minerals such as; silicon, magnesium, iron calcium, and aluminum. The upper layer is called Lithosphere which is rigid with temperature about 400 C˚, while, the lower layer is called Asthenosphere, which is a ductile layer with temperature from 300 – 500 C˚ (Katniss, 2013). The crust floats on the mantle. It is composed of iron, oxygen, silicon, magnesium, nickel and other elements.

Land Masses

Many processes emerged from the ocean. We heard many times in the news that there are some islands appeared in Oceans such as; Hunga Tonga Island in the Pacific Ocean near to Japan coast.

Hughes, R., Hunga Tonga volcano eruption forms new S Pacific Island,[online], http://www.bbc.com/news/world-asia-31848255, [Accessed 08/07/2015].

The Mid-oceanic Ridge is a phenomenon of forming underwater mountains. It forms by rising of magma through the weakest point occurred in the oceanic crust. This magma moved as lava forming a new crust upon cooling. Volcanic activities form the land masses. The lava traveled from the earth’s core to the crust forming a new crust after cooling.

The distribution of the continents now a day is not as same as 250 million years ago. During Permian Period (250 million years ago) (Geology.com, 2015), there were only ocean and supercontinent called Pangea. 200 million years ago it began to break up to form two supercontinents; Gondwana and Laurasia. In Jurassic Period (145 million years ago) and Cretaceous Period (65 million years ago) the two supercontinents broke up to the small land masses until the continents that are known today are formed.This processes called Continental Drift, which is an explanation of the movement of the continents. I guess this is the reason behind the discovery of Mosasaurs fossils in both South Africa and South America.

pangea-continental-drift

Geology.com, Pangea Supercontinent, [online], http://geology.com/articles/supercontinent.shtml, [Accessed 08/07/2015].

Plate Tectonic is the other processes that associate with the continental draft. It is a study of the movement of Earth’s plates. The movement of the plate is estimated at 1-10 cm per year (Enchanted Learning, 2015). There were three types of plate movement. Divergent Plat Boundaries, as the two plates move apart from each other and new lithosphere is being created. If the movement happened in the oceanic crust, mid-oceanic ridge occurs, for instance, the Mid-Atlantic Ridge and the East Pacific Rise. Convergent Plat Boundary is the second type of plate tectonics. The plates move toward each other. Subduction is the movement of two different plates – oceanic and continental, as the oceanic plate is forced under the continental plate. If the two plates were oceanic, the denser one would move under the lighter one. If the two plates were continental, a collision zone existed, and a mountain range is formed. The Himalaya is a good example.The third type is called Conservative Plate Boundary or Lateral Slipping Plate Movement. It is a transform plate boundary as the two plates move sideways against each other. This is called transform faults. They are mainly formed in the ocean floor.

Abyssal Plain is a flat area occurs in depth between 4000 m – 3000 m (National Geographic, 2015), covers 40% of the ocean floor (Science Encyclopedia, 2011). It contains fine-grained sediments such as clay and silt. A mid-oceanic ridge, seamount or abyssal hills, and oceanic trench exist in Abyssal Plain. The underneath magma pressure forms Seamounts. The magma tries to evolve which is facing resistance from abyssal plain forming small mountains or sometimes an island. Seamounts lie above hotspots. As a result of plate tectonics, the oceanic abyssal plain moves forming a chain of seamounts. Micronutrients exit in the ocean floor. They are important to stimulate phytoplankton production which is expected to increase photosynthesis and remove CO2 from the atmosphere. Micronutrients are metals that are controlling the phytoplankton growth in the ocean keeps the O2 and CO2 amounts stable in the ocean. These elements are Zinc (Zn), Ferrous (Fe), Selenium (Se), Manganese (Mn) and Copper (Co).

All those oceanic features might be affected by the earth’s magnetic field. Magnetic rocks generate the Magnetic field. Temperature, pressure, and composition of the outer core of Earth change the magnetism of Earth. The magnetic field can be produced by the flow of liquid iron that creates electrical currents. The generated magnetic field can influence ocean salinity and current. The dissolved salts in ocean water exist as positive and negative ions. By the movement of ocean water, the ions are scattered by the earth’s magnetic field. Negative and positive ions move aside each other creating loop of electrical currents in the water. The change in the Earth’s magnetic field may affect the thermal mixing of the oceans. The change in the polarity of the Earth can influence Mid-Oceanic Ridges. Magnetic bands are formed surround them with a polarity opposite to the surrounding band. It is a reason of finding the seafloor stripped. Some stripes match with the Earth polarity while others are in an opposite direction. I guess this is a very remarkable reason of how magma results from mid-oceanic ride oceanic ridge show polarity stripes reverse to each other.

Ocean Composition:

The marine environment is divided into three life zones; the intertidal zone, the benthic environment, and the pelagic environment. The intertidal zone is the zone where organisms live in ocean shoe. The pelagic environment is the zone where organisms live in water. It is divided into neritic and oceanic zones. The oceanic zone is divided into several zones according to their depth; The Epipelagic zone (from 0-200 m), Mesopelagic Zone (200 m – 1000 m), Bathypelagic Zone (1000 m – 2000 m), Abyssopelagic Zone (2000 m – 6000 m), and Hadalpelagic Zone (more than 6000 m) (Robertson, 2013). The Benthic Environment consists of sediments (sand and mud) as many animals live such as worms and clams (V. Tait & A. Dipper,1998).

 The properties of seawater:

Seawater is a liquid, and it has some characters based on its physical states:

  • Temperature: is different depending on salinity; as not all seawater temperature is same. The rage is from the freezing point (-1.9 ˚C) to around 30 ˚C in the tropical oceans. ( Gordon, 2004). However, in open oceans the temperature varies between -2˚C and +30˚C (Mladinove, 2013). In Deep Ocean, the temperature is very low, and few organisms can survive in these cold water.
  • Salinity: is the amount of salt that can dissolve in the water. The salinity of water has a significant effect on marine organisms as some organisms die in fresh water; however, a slight change in water salinity will put organisms in danger.
  • The density of seawater depends on the salinity and temperature of it. The higher salinity, the higher density, the lower temperature.
  • pH: measures how acidic or basic is the seawater epa (EPA, 2012). The pH of seawater is ranged between 7.5 to 8.5. (Fondriest Environmental Inc., 2015). PH of water depends on the amount of CO2 as it is the most common cause of sweater acidity. Any change of pH of seawater may kill marine organisms.
  • Buoyancy in a salty water is greater than the surface does in fresh water. Objects can float on the salty surface better than it does in fresh water. It helps organisms that on the top of the ocean’s surface.

Physical Properties of Sand and Rock Formation

Sand and marine sediments are formed by transportation of terrestrial sediments to marine. The method of transportation depends on some physical properties of sand and rocks such as the grain size and sorting. The grain size classes are divided into many classes. Boulder – that the diameter is bigger than 25 cm, cobble- the diameter is between 6.4 cm to 25 cm. Pebble – the diameter is 4mm to 6.4 cm. Granule – the diameter is from 2mm to 4 mm. Sand – the diameter is from 1/16 mm to 2mm. Silt -the diameter is between 1/256 to 1/16. Clay, from 1/4096 mm to 1/256 mm and colloidal, less than 1/4096 mm (P. Trujillo & V. Thurman, 2014). According to the sediment size, the transportation of sediment is varied. The smaller grain size needs low-velocity current. As sediment size increases, deposition increases, and transportation decreases. The grain size is proportional to the energy of transportation and depositions. Sorting is one of the physical properties that associate with rock and sand formation. Sorting is a measure of grain size uniformity. Well-sorted grains have same size particles while poorly sorted grains have different size particles. The well-sorted grains are transported faster than poorly sorted. Sediments become lithified and converted to rock and form sedimentary rock over time. The textural maturity of sediments can be classified into well-rounded, sub-rounded and angular. Well rounded and well-sorted grains are transferred longer distance of transportation that poorly sorted and angular grains.

Effect of climate on Sea Level

The sea level of the ocean is affected by climate. Any change in climate temperatures will cause a change in sea levels. The global sea level is raised at the rate of 1mm to 2.5mm per year since 1900 (NOAA, 2014) as a result of global warming. The causes of sea level rise can be illustrated in the following three processes:

  • As the temperature of water increases, the water expands. Its density goes down as temperature increases. This is called thermal expansion of the sea surface. During the second half of the 20th century, the sea level raised about 2.5 cm due to thermal expansion. The rate of rising has increased to about three times this rate during the early 21st century ( Watt, 2013). Over the 21st century, the IPCC’s Fourth Assessment report projected that thermal expansion will lead to the sea level rise of about 17 cm to 28 cm (IPCC, 2013).
  • The second impact is the melting of glaciers and ice caps. According to the IPCC’s Fourth Assessment, the sea level raised to about 2.5 cm due to melting of the mountain glaciers and ice cap during the second half of the 20th century (Climate Institute, 2010).
  • The loss of ice masses from Greenland and Antarctica. As per IPCC Fourth Assessment Report, Greenland and Antarctica would cause a rise in the sea level about 2 cm each.

I guess, melting of glaciers and ice caps from the mountains and ice loss from Greenland and Antarctica is the most harmful impact on sea level. It also affects the marine habitat. The marine conservation strategies and legislation are critical to protecting the marine environment.

There are some strategies to control global warming effect. Some of these strategies are Kyoto Protocol & Climate Change Act in the UK. Kyoto Protocol is an international agreement initiated by the United Nation Framework Convention on climate change. It sets a target to reduce the emission of greenhouse gases (GHGs). It is the one of the most efficient and successful legislation in controlling global warming. The Europe community and 37 industrialized countries targeted to reduce GHG emission by an average 5% against 1990 levels during the first commitment period, and 18% below 1990 level in the second period (UNFCCC, 2014). This is an excellent commitment, and it makes this protocol efficient and reliable. The GHG emission has been reduced in many countries due to the implementation of Kyoto Protocol. In Canada, it achieved 6% total reduction in 2012 than 1990 level, and in Europe, 8% total reduction achieved than 1990 levels (Enzler, 2013). These achievements are magnificent initiative, but I think these percentages should be increased in the future. In the UK, the Climate Change Act sets 4 carbon budgets with at least 80% reduction in CO2 emissions below 1990 levels by 2050 (DECC, 2014). The UK has met the first carbon budget. I think the UK can achieve the other 3 carbon budget as data shown in the table below.

Table.png

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/368021/Updated_energy_and_emissions_projections2014.pdf, [Accessed 16/07/2015].

Conservation of marine habitat and overfishing

There are several important legislation and strategies in order to conserve marine habitat. Some of these strategies are mentioned below.

EU Marine Strategy Framework Directive (2008/56/EC)

This directive is aimed to protect the marine environment across Europe. It was adopted in June 2008. It sets a target of “Good Environment Status (GES)” that is planned to be achieved in EU marine waters by 2020. Each Member State should develop marine strategies and conduct a detailed assessment of the state of the environment, a definition of “GES” at the regional level, and the establishment of clear environment targets and monitor programs (JNCC, 2014). I believe that it is the one of the most efficient EU legislation in protecting the marine environment. Over the years, it succeeded to implement the assessment and status of Member States water, and it addressed the points that need to work on.

International Maritime Organization Convention

This is a convention on the prevention of marine pollution. It prevents dumping of wastes and other matters in marine. It came into force in 2006. It requires appropriate prevention measures to be taken to avoid marine pollution. It states that polluter should handle the cost of contamination and should bear that contracting parties should ensure pollution are not transferred from one part to another. This is a good legislation as the 1996 protocol restricts all dumping activities except for the permitted list. The contracting parties have taken action towards increasing of CO2 concentrations in the atmosphere and marine environment by using new technologies that aim to engineer the climate. Personally, I guess this convention is not enough or effective to protect the marine environment as I cannot see any legal obligation or disciplinary action against the polluter.

The International Trade in Endangered Species of Wild Fauna & Flora (CITES)

Initiated in 1963 in the IUCN General Assembly, it aimed to protect endangered plants and animals. It is conducted at Washington in 1973 and came into force in 1975. Around 100 countries signed this agreement. I can say that this is a magnificent piece of legislation as it protected many endangered species; however, I believe it is not enough to protect all Earth’s marine environment. The number of signed countries should be increased. Around 55 countries have proposed 70 proposals to improve conservation and sustainable use of marine species. Several sharks, timber species, polar bears and African elephants have been protected by this legislation (CITES, 2013). CITES succeeded to save five species of sharks and two manta ray species – the Great Hammerhead Shark (Sphyrna mokarran), smooth hammerhead shark (Spyrna zygaena), the scalloped hammerhead shark (Sphyrna lewini), the oceanic whitetip shark (Carcharhinus longimanus) and manta rays (Manta spp.). They are now listed (Defenders of Wildlife, 2015). Around 103 fish species are listed in CITES. There are 28,000 plant species, and 5000 Animal species are listed in CITES. In the Appendix I there are 900 species listed, 30,000 species in Appendix II and 300 in the Appendix III (CITES, 2013).

As a result of this convention, the UK has established Marine Protective Areas (MPAs). Around 16% of the UK, waters are within MPAs. I think this is an effective strategy to protect the marine biology as the UK has 108 Special Areas of Conservation, 110 Special Protection Areas, 29 Marine Conservation Zones, and 30 Natural Conservation Marine Protection Areas (JNCC, 2015). I can say that the UK is doing great. Despite the fact that the CITES is effective in most of the world’s countries, it failed to control the marine environment is less developed countries, such as Egypt. Egypt has two coasts (Red Sea Coast in East, and the Mediterranean Sea in the North). The overfishing is threatening Egypt coasts. The Egyptian government failed to prevent their marine environment as the number of marine species reduced. I suggest that the United Nations should work hard with less developed countries.

Conclusion

Earth is affected by global warming. Sea level rises due to the increase of Earth’s temperature which affects the marine habitat. The conservation of the marine environment is a must in order to protect our marine species. Several Strategies such as EU Marine Strategy Framework Directives, Kyoto Protocol, Climate Change Act, International Maritime Organization Convention, and CITES are implemented in many countries. They succeeded in protecting the huge number of the marine environment.

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