From our small, terrestrial vantage points, we sometimes struggle to imagine the ocean’s impact on our lives. We often think of the ocean as a flat expanse of blue, with currents as orderly, if sinuous, lines. In reality, it is vaster and more chaotic than we can imagine. Its waters move in ways that lack a terrestrial equivalent and, in doing so, the ocean shirks tidy metaphor…..Story continues…
By: David Garczynski
Source: Nautilus
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Critics:
Scientists believe that a sizable quantity of water would have been in the material that formed Earth. Water molecules would have escaped Earth’s gravity more easily when it was less massive during its formation. This is called atmospheric escape. During planetary formation, Earth possibly had magma oceans. Subsequently, outgassing, volcanic activity and meteorite impacts, produced an early atmosphere of carbon dioxide, nitrogen and water vapor, according to current theories.
The gases and the atmosphere are thought to have accumulated over millions of years. After Earth’s surface had significantly cooled, the water vapor over time would have condensed, forming Earth’s first oceans.The early oceans might have been significantly hotter than today and appeared green due to high iron content. Geological evidence helps constrain the time frame for liquid water existing on Earth.
A sample of pillow basalt (a type of rock formed during an underwater eruption) was recovered from the Isua Greenstone Belt and provides evidence that water existed on Earth 3.8 billion years ago. In the Nuvvuagittuq Greenstone Belt, Quebec, Canada, rocks dated at 3.8 billion years old by one study and 4.28 billion years old by another show evidence of the presence of water at these ages.
If oceans existed earlier than this, any geological evidence either has yet to be discovered, or has since been destroyed by geological processes like crustal recycling. However, in August 2020, researchers reported that sufficient water to fill the oceans may have always been on the Earth since the beginning of the planet’s formation. In this model, atmospheric greenhouse gases kept the oceans from freezing when the newly forming Sun had only 70% of its current luminosity.
The origin of Earth’s oceans is unknown. Oceans are thought to have formed in the Hadean eon and may have been the cause for the emergence of life. Plate tectonics, post-glacial rebound, and sea level rise continually change the coastline and structure of the world ocean. A global ocean has existed in one form or another on Earth for eons. Since its formation the ocean has taken many conditions and shapes with many past ocean divisions and potentially at times covering the whole globe.
During colder climatic periods, more ice caps and glaciers form, and enough of the global water supply accumulates as ice to lessen the amounts in other parts of the water cycle. The reverse is true during warm periods. During the last ice age, glaciers covered almost one-third of Earth’s land mass with the result being that the oceans were about 122 m (400 ft) lower than today. During the last global “warm spell,” about 125,000 years ago, the seas were about 5.5 m (18 ft) higher than they are now. About three million years ago the oceans could have been up to 50 m (165 ft) higher.
The entire ocean, containing 97% of Earth’s water, spans 70.8% of Earth’s surface, making it Earth’s global ocean or world ocean.This makes Earth, along with its vibrant hydrosphere a “water world”or “ocean world”, particularly in Earth’s early history when the ocean is thought to have possibly covered Earth completely. The ocean’s shape is irregular, unevenly dominating the Earth’s surface.
This leads to the distinction of the Earth’s surface into a water and land hemisphere, as well as the division of the ocean into different oceans. Seawater covers about 361,000,000 km2 (139,000,000 sq mi) and the ocean’s furthest pole of inaccessibility, known as “Point Nemo”, in a region known as spacecraft cemetery of the South Pacific Ocean, at 48°52.6′S 123°23.6′W. This point is roughly 2,688 km (1,670 mi) from the nearest land.
Ocean water represents the largest body of water within the global water cycle (oceans contain 97% of Earth’s water). Evaporation from the ocean moves water into the atmosphere to later rain back down onto land and the ocean. Oceans have a significant effect on the biosphere. The ocean as a whole is thought to cover approximately 90% of the Earth’s biosphere.
Oceanic evaporation, as a phase of the water cycle, is the source of most rainfall (about 90%), causing a global cloud cover of 67% and a consistent oceanic cloud cover of 72%. Ocean temperatures affect climate and wind patterns that affect life on land. One of the most dramatic forms of weather occurs over the oceans: tropical cyclones (also called “typhoons” and “hurricanes” depending upon where the system forms).
As the world’s ocean is the principal component of Earth’s hydrosphere, it is integral to life on Earth, forms part of the carbon cycle and water cycle, and – as a huge heat reservoir – influences climate and weather patterns.Ocean water contains large quantities of dissolved gases, including oxygen, carbon dioxide and nitrogen.
These dissolve into ocean water via gas exchange at the ocean surface, with the solubility of these gases depending on the temperature and salinity of the water.The four most abundant gases in earth’s atmosphere and oceans are nitrogen, oxygen, argon, and carbon dioxide. In the ocean by volume, the most abundant gases dissolved in seawater are carbon dioxide (including bicarbonate and carbonate ions, 14 mL/L on average), nitrogen (9 mL/L), and oxygen (5 mL/L) at equilibrium at 24 °C (75 °F).
All gases are more soluble – more easily dissolved – in colder water than in warmer water. For example, when salinity and pressure are held constant, oxygen concentration in water almost doubles when the temperature drops from that of a warm summer day 30 °C (86 °F) to freezing 0 °C (32 °F). Similarly, carbon dioxide and nitrogen gases are more soluble at colder temperatures, and their solubility changes with temperature at different rates.
Our Oceans Conference Reminds Us of the Ocean’s Incredible Value
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