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1)How are the oceans important for the creation of Earth’s oxygen?

2)How do the oceans regulate Earth’s temperature?

3)What part did the oceans play in the evolution of life?

4)WHY DO THE OCEANS CONTAIN SALTWATER?

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Even though technically the planet is covered by one large body of saltwater often referred to as the ocean, scientists often divide that ocean into five geographically distinct regions: the Arctic, Atlantic, Indian, Pacific, and Southern. Earth's ocean covers about 71 percent of its surface, yet researchers have only explored about 5 percent of its vast territory, leading scientists to contend that only a small fraction of all ocean species have been identified. The oceans also have a profound effect on the planet's atmosphere and climate, as they help create oxygen and redistribute heat on a global scale.

Critical Thinking Questions

How are the oceans important for the creation of Earth's oxygen?

How do the oceans regulate Earth's temperature?

What part did the oceans play in the evolution of life?

Origin of the Oceans

When Earth was first formed about 4.5 billion years ago, the planet was covered with molten rock, and while water vapor was present in gaseous form, the temperature was too hot to support liquid water. Yet, scientists have found evidence of liquid water on Earth within the span of a few hundred million years. Astronomers and planetary scientists have several theories as to how liquid water first appeared on Earth but have not come to a definitive conclusion as to the exact cause.

However, the more widely accepted theory is that Earth already had acquired most of its water from the primordial cloud of gas and dust that formed the solar system, and the molten Earth released an abundance of water vapor into its early atmosphere. As the planet slowly cooled, this water vapor condensed into liquid water and fell from the sky in massive rainstorms, and over the course of millions of years, these storms covered the planet in water.

Connections: Why Do the Oceans Contain Saltwater?

All the salt in Earth's oceans originally came from rocks on the land, but over the course of many millions of years, rainwater falling on the land slightly eroded away minerals from rocks and soil, and the mineral sediments were carried by rivers and streams and eventually made their way into the oceans. When ocean water evaporated into the atmosphere, the minerals were left behind to slowly accumulate. Two of the main substances dissolved in the oceans were chloride and sodium, the same substances that make up table salt, unlike sea salt, which contains several other mineral substances including magnesium, calcium, and potassium.

Impact of the Oceans

The earliest known life on Earth were single-celled organisms that are believed to have formed about 3.8 billion years ago, but may have developed even earlier. What is beyond dispute is that life first developed and thrived in the planet's vast oceans in which an early type of organism known as cyanobacteria, or blue-green algae, used energy from the sun to produce the oxygen in Earth's atmosphere. Even today, about 70 percent of all the planet's oxygen is produced by the ocean's plant life.

Life was exclusively confined to the oceans until about 500 million years ago when the first primitive land animals ventured onto dry ground, and while life proliferated on land, it continued to flourish in the oceans. By the late 2010s, scientists at the World Register of Marine Species estimated that about 233,280 species lived in the oceans but were also quick to point out that about 95 percent of the oceans remain unexplored. With this in mind, researchers believe that the number of known marine species may only be about 9 percent of the true number.

The sheer size of the oceans also makes them an essential part of the process by which the planet redistributes heat and regulates its climate. Because the oceans cover about 71 percent of Earth's surface, they also absorb most of the heat radiation from the sun. Much of this absorption occurs in the tropical regions near the equator where the sun's rays are strongest. The heating of the oceans causes water to evaporate, or change from liquid into water vapor, and evaporation creates rain and storms that are then carried by the winds across the planet. About 90 percent of the rain that falls on land began as ocean water that was evaporated into the planet's atmosphere.

Most of Earth's weather patterns are fueled by large moving rivers of ocean water called currents, which are caused by a number of factors including the Earth's rotation, tides, winds, and the density of the water. Currents act as a giant transportation system, moving warmer water away from the equator toward the poles, and cooler water toward the equator, a process that helps regulate the planet's temperature and offset the imbalance of heat absorption near the equator. Without ocean currents, the equator would be unbearably hot, and the polar regions would be so cold as to be nearly uninhabitable.

Geography of the Oceans

The Earth's oceans cover about 129.4 million square miles (335.3 million square kilometers) of Earth's surface and have a total volume of about 321 million cubic miles (1.3 billion cubic kilometers) of water, more than 96 percent of all the water on Earth. While this vast global ocean is often divided into five separate ocean basins, prior to 2000, scientists recognized only four ocean basins, but added the Southern Ocean to the list that year.

As the name suggests, the Southern Ocean completely surrounds the continent of Antarctica and is generally accepted to begin about 60° south latitude and extends for about 8.5 million square miles (22 million square kilometers). The smallest and shallowest ocean is the Arctic Ocean at the northern polar region, which covers about 5.4 million square miles (14 million square kilometers) and includes many of the bays and seas that surround northern Canada, Alaska, Greenland, Norway, and Russia. The ocean typically remains frozen from October through June.

At 28.4 million square miles (70.4 million square kilometers), the Indian Ocean is the third largest on Earth and borders Asia to the north, Africa to the west, Australia to the east, and the Southern Ocean to the south and also includes both the Red Sea and the Persian Gulf. The Atlantic Ocean extends for about 41.1 million square miles (106.4 million square kilometers) from the Arctic Ocean to the Southern Ocean and is bordered on the west by North and South America and on the east by Europe and Africa.

The Pacific Ocean is by far the largest ocean on Earth and with an area of 63.8 million square miles (165.2 million square kilometers), it covers about 46 percent of Earth's water surface and nearly a third of its total surface. It extends from the Arctic to the Southern oceans and borders North and South America to the east and Asia and Australia to the west. It is also the world's deepest ocean, reaching a depth of 35,827 feet (10,920 meters) at the Mariana Trench in the western North Pacific.

Source Citation

# data[].attributes.attachment_link.description
Even though technically the planet is covered by one large body of saltwater often referred to as the ocean, scientists often divide that ocean into five geographically distinct regions: the Arctic, Atlantic, Indian, Pacific, and Southern.

# data[].attributes.body
click the link to see annotation

# data[].attributes.attachment_link.description
Create a new document and edit with others at the same time -- from your computer, phone or tablet. Get stuff done with or without an internet connection. Use Docs to edit Word files. Free from Google.

# data[].attributes.body
click the link to see annotation

# data[].attributes.attachment_link.description
Create a new document and edit with others at the same time -- from your computer, phone or tablet. Get stuff done with or without an internet connection. Use Docs to edit Word files. Free from Google.

# data[].attributes.body
click the link to see annotation

# data[].attributes.attachment_link.description
Create a new document and edit with others at the same time -- from your computer, phone or tablet. Get stuff done with or without an internet connection. Use Docs to edit Word files. Free from Google.

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1)Why is ocean pollution a problem?

2)Which type of ocean pollution do you think is the most dangerous? Why?

3)What do you think would be the best way to combat ocean pollution?

4)What types of contaminants cause various forms of ocean pollution?

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Article #3" what pollution does to our ocean"

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Article #3" what pollution does to our ocean"

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Ocean pollution is the introduction of harmful substances into the marine environment by humans. Such pollution can threaten aquatic life, reduce the quality of ocean water, hamper marine activities, and even endanger human health. Ocean pollution is caused by a wide variety of potentially hazardous contaminants, including chemicals, plastics, garbage, sewage, artificial light, and noise. These pollutants are all either directly dumped into the oceans by humans or the result of human activities on land. In any event, ocean pollution is a serious concern that urgently requires the attention of people and governments around the world if it is to be appropriately addressed.

Critical Thinking Questions

Why is ocean pollution a problem?

Which type of ocean pollution do you think is the most dangerous? Why?

What do you think would be the best way to combat ocean pollution?

The Problem of Ocean Pollution

The Atlantic, Pacific, Indian, Arctic, and Southern Oceans account for more than 70 percent of the Earth's surface. Their sheer size led humans to conclude for generations that there was no harm in dumping waste into the sea, as it seemed only logical to assume that the oceans were so vast and deep that practically no amount of waste could possibly cause serious damage to the marine environment. These assumptions, it turned out, were far from correct, and in recent decades, research has revealed that ocean pollution is a serious issue that poses a legitimate threat to both marine and human life.

The earliest real efforts to combat ocean pollution did not formally commence until the 1970s. Up to that point, humans willfully dumped untold amounts of garbage, sewage, and a variety of chemical, industrial, and radioactive waste products into the oceans. The first notable measure aimed at curbing such harmful practices was an international agreement penned in 1972 and enacted in 1975 called the London Convention that attempted to establish protections for the marine environment by instituting a number of regulatory programs and prohibiting the dumping of hazardous materials into the ocean. This was later followed by the London Protocol in 1996, which was an updated agreement banning the dumping of nearly all other waste and harmful materials. While such efforts did much to reduce damage to the ocean environment, ocean pollution remains a serious ecological problem.

What Is Ocean Pollution?

Ocean pollution is the contamination of marine environments through humans' dumping various pollutants into the oceans. Ocean pollution can also be caused by pollutants that leach into the oceans through other waterways as a result of human activities on land, such as agriculture or mining. Regardless of how they reach the ocean, these pollutants damage the marine environment and pose a direct threat to the many organisms that call such places home, often diminishing water quality or causing bodily harm. Some pollutants can also sink to the ocean floor, where they can be eaten by small animals and are introduced into the food chain as a result, thus posing a risk to humans and other animals as well.

Many types of contaminants cause various forms of ocean pollution, the most common of which are chemicals. Chemical pollution occurs when hazardous chemical contaminants are introduced into the marine environment such as oil, fertilizers, detergents, pesticides, and sewage. While many of these chemical pollutants are purposely dumped into the sea, others are unintentionally released due to spills or other accidents. Some chemical pollutants tied to human activity on land reach the ocean after first leaching into streams, rivers, and bays. Chemical pollution can have a severely adverse effect on marine environments, sometimes deoxygenating water and leading to the formation of massive dead zones where few organisms can survive.

Another major type of ocean pollution is garbage and plastic pollution. While some garbage is dumped directly into the ocean, a much larger amount reaches the sea from land-based sources after traveling through sewers and storm drains. The longest-lasting and most harmful form of garbage pollution in the ocean is plastic, which may be in the form of grocery bags, water bottles, drinking straws, and food containers. Fish and seabirds often try to eat plastic debris or become entangled in larger plastic soda can rings or grocery bags. Worse yet, plastic garbage that accumulates in the ocean can be pulled together to form large floating garbage patches like the Great Pacific Garbage Patch that are even more dangerous for wildlife and the ocean itself.

Not all forms of ocean pollution are physical, however. Artificial light and noise can also act as pollutants in the ocean. While artificial light is typically regarded as a land-based form of pollution, it can have a negative effect on marine environments as well. When it is emitted by large urban centers and penetrates the surface of the sea, artificial light can interfere with ecosystems that exist in the shallow waters just off the coast. In such ecosystems, artificial light can interfere with the visual cues tied to circadian rhythms, which are key to the timing of activities like feeding, reproduction, and migration and can also throw off the balance of life in coastal ecosystems by making it easier for predators to track prey at night. Noise pollution produced by ships, oil rights, or sonar devices can cause other problems in marine environments because whales and other marine mammals depend on non-visual communication to survive. Noise pollution can interfere with their natural means of communication and thereby hamper their ability to hunt or reproduce.

Connections: Microplastics

One of the most widespread and insidious forms of ocean pollution, microplastics are tiny plastic debris that are no more than five millimeters in length and found all over the oceans, even in some of most remote locations. Microplastics can also be ingested by a wide range of marine animals, which means that they are finding their way into the food chain and are a threat not only to marine lifeforms, but also to the humans and other animals that feed on them. Once ingested, microplastics can damage organs and leach dangerous chemicals that can interfere with immune response, reproduction, and growth, which means that microplastics are a particularly problematic type of ocean pollution.

Combating Ocean Pollution

The effort to reduce ocean pollution is a complex and multifaceted matter. On the individual level, people can fight ocean pollution by not dumping toxic substances into the ocean or storm drains, minimizing the use of fertilizers and pesticides, reducing automobile emissions, and supporting improved sewage treatments methods. In terms of larger-scale measures, governments can enact legislation aimed at protecting marine environments, cleaning up existing contamination, and minimizing the risk of future pollution.

Source Citation

# data[].attributes.attachment_link.description
Ocean pollution is the introduction of harmful substances into the marine environment by humans. Such pollution can threaten aquatic life, reduce the quality of ocean water, hamper marine activities, and even endanger human health. Ocean pollution is caused by a wide variety of potentially hazardous contaminants, including chemicals, plastics, garbage, sewage, artificial light, and noise.

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1)Why are the oceans getting warmer?

2)Why are the ocean levels rising ?

3)Why have the upper oceans lost 1-3% of the oxygen?

4)Why is the soil at the north pole almost permanently frozen ?

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Oceans are increasingly bearing the brunt of global warming

THE WORLD'S oceans are getting warmer, stormier and more acidic. They are becoming less productive as the ecosystems within them collapse. Melting glaciers and ice sheets are causing sea levels to rise, increasing the risk of inundation and devastation to hundreds of millions of people living in coastal areas.

The latest special report from the Intergovernmental Panel on Climate Change (IPCC), on how the oceans and frozen regions of the planet are changing in response to the rising carbon dioxide levels in the atmosphere, is a predictably grim read. The final text, pored and argued over by scores of scientists and policymakers from 36 countries over the course of marathon meetings in the past week in Monaco, makes reference to almost 7,000 relevant scientific studies.

For decades, the oceans have provided a buffer against the full impact of a warming planet. Since 1970, says the report, they have soaked up more than 90% of the excess heat associated with greenhouse gases and absorbed around a quarter of the carbon dioxide emitted from cars, power stations and factories. As oceans warm, the layers of water within them mix less and the supply of oxygen and nutrients decreases. The upper layers of the world's seas have lost 1-3% of their oxygen in recent years and the increased absorption of CO² has made the water more acidic, complicating life for creatures such as coral that need to build carbonate shells. As this continues, the report predicts that around 15% of animals are likely to disappear by the end of the century, and that fish catches could decline by as much as a quarter relative to average levels between 1986 and 2005.

Farther towards the poles, the permafrost--permanently frozen soil--is at risk. Even if the average global temperature increase is limited to 2°C above pre-industrial levels--already an ambitious target--a quarter will thaw. If greenhouse-gas emissions and temperatures increase further, almost 70% of this near-surface permafrost could melt. Frozen in that earth are 1,460-1,600 gigatons of carbon, says the report, almost twice the amount already in the atmosphere, much of which could be released if the soil thaws.

The IPCC process is rooted in science but reaching any consensus is tricky. The politics demand some sacrifices. Big producers of fossil fuels such as Saudi Arabia, for example, often quibble with the strong conclusions in such reports. For the sake of unanimity, some of the language was weakened. Even so, this latest report provides a new, unified portrait of Earth's oceans and ice realms that should better inform policymakers. And better informed could mean better protected.

Source Citation

# data[].attributes.attachment_link.description
Oceans are increasingly bearing the brunt of global warming THE WORLD'S oceans are getting warmer, stormier and more acidic. They are becoming less productive as the ecosystems within them collapse. Melting glaciers and ice sheets are causing sea levels to rise, increasing the risk of inundation and devastation to hundreds of millions of people living in coastal areas.

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1)What does the ocean offer to us humans?

2)How much of the earths surface is covered by the ocean?

3)What are some of the many foods the ocean has to offer?

4)What are some economic benefits of the ocean?

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Article #1 " why we should care about the ocean"

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Article #1 " why we should care about the ocean"

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national oceanic and atmospheric administration

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National Ocean Service National Oceanic and Atmospheric Administration U.S. Department of Commerce