Although the Earth’s oceans remain one of the most mysterious areas on the planet, scientists have now determined how deep they are and how much water they contain.
Using satellites, scientists were able to estimate these recent measurements. The scientists worked out that the ocean’s volume is 0.3 billion mi3 (cubic miles). This number is lower than previous estimates of the ocean’s volume.
Scientists mapped and quantified its surface area and multiplied that by its average depth to work out the quantity of water in the ocean. (Technically speaking, there are four oceans, or maybe five, depending on who’s counting.)
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Let’s get one thing clear. Although there is only one ocean globally, the vast body of saltwater that covers 71% of the Earth’s surface is divided geographically into distinct regions. For historical, cultural, and scientific reasons, these boundaries have changed over time.
Historically, we’ve had four “oceans” named the Arctic, Indian, Pacific, and Atlantic. The Southern (Antarctic) ocean is now recognized as the fifth ocean by some countries and the USA. The most well-known oceans are the Pacific, Atlantic, and Indian.
This makes the newest named ocean the Southern Ocean. The US Board on Geographic Names recognizes it as the ocean that extends from Antarctica’s coast to latitude 60° south.
In 2000, the IHO (International Hydrographic Organization) proposed the boundaries of this ocean. The boundaries have not been ratified by the IHO because not all countries agree with them.
The math of figuring out how much water is in the ocean
1.3 billion cubic kilometers. That’s the approximate amount of water that oceans are said to contain. Now, 1 km3 = 1 x 109 liters (1 x 109 is a trillion.)
Therefore, there are approximately 1,300 trillion, trillion liters of water in the oceans, which is 1.3 sextillion liters.
To calculate the volume of the ocean in gallons, convert it from liters to gallons. There are 3.78541178 liters in a gallon. Multiplying 1.3 sextillion by 3.78541178, we get 343,000,000,000,000,000,000 gallons, or thereabouts.
As noted at the start of this article, that’s 343 quintillion gallons.
The depth estimate of 2.3 miles is approximately 69 to167 feet lower than previous estimates. Certain places in the ocean are far deeper than the average.
For example, the Mariana Trench is nearly 7 miles deep! Other areas, however, like the Mid-Atlantic Ridge, are shallower than the average depth.
According to the researchers, the whole world’s ocean volume is lower than previously estimated.
It amounts to approximately five hundred times that of the Great Lakes or five times the Gulf of Mexico’s volume. Although it may seem like a lot, it is only 0.3 percent less than what was estimated 30 years ago.
Historical estimates of the quantity of water in the oceans weren’t that far off
This small difference shows how precise even primitive measurement techniques were in estimating the volume of the ocean.
For example, John Murray used lead weights to determine the ocean’s volume. This figure was calculated by dragging a rope from a ship and calculating the ocean area.
It is only 1.2 percent more than National Environmental Satellite, Data and Information Service (NOAA) geophysicists Charette and Walter H.F. Smith reported.
Echosounders were used by researchers to improve depth estimations starting in the 1920s. In modern times, Smith, along with others, pioneered satellites for ocean volume calculations.
The trend towards a gradual lowering in volume estimates does not mean that the ocean is losing water. Instead, we are better able to find formations like undersea mountain ranges that occupy space that would otherwise be occupied by water.
Satellite measurements show more mountainous and bumpier ocean bottoms than previously thought.
Satellites don’t actually measure the bottom of the ocean. Satellites measure the ocean’s surface to see what is beneath. If a mountain range is found under an ocean area, it will cause the ocean’s surface to bulge outward.
Smith stated that the satellite project covered almost all of the oceans in the world. The exception was some Arctic areas, which are still covered by ice.
This new map shows the world’s oceans in greater detail, thereby giving us a more accurate picture of the ocean’s volume and shape.
However, satellite measurements have some flaws as there is a problem with spatial resolution. We are measuring the sea surface, which is affected by mountains.
But we see only huge mountains and only in a blurred manner. This resolution is 15 times lower than our Mars and Moon maps.
According to the researchers, this means that more ship-based measurements will be required to “fine-tune” satellite data. Ship-based sonar and other instruments have only mapped 10% of the Earth’s ocean floor.
One expert noted gaps in “echo-sounding measurements as wide as New Jersey.”
US Navy estimates suggest one ship would have to spend two hundred years to map the depth of the entire ocean floor with echosounders.
The Earth is watery, so how much water does this planet have? The oceans contain 96.5 percent of Earth’s water, and the Earth’s surface is 71% covered by water.
There’s also water vapor in the air to consider. It is in glaciers, lakes and rivers, ice caps, and groundwater like soil moisture, aquifers, as well as in all of us and even our pets.
Water never stays still. The water cycle is responsible for the planet’s constant water supply moving from one place and one form to another. Without the water cycle, things would become pretty boring!
If all the Earth’s water could be put into bubbles representing relative amounts of Earth water to its size, the water spheres would be surprisingly small.
That’s because they really are small relative to the Earth’s size. The largest sphere would contain all the water on and above the Earth. Its volume would be approximately 332,500,000 mi3, and its diameter would be 860 miles.
There would be a smaller sphere with a volume of about 2,551,000 mi3 and a diameter measuring around 169.5 miles. This water is freshwater, and we all use it every day. However, a lot of it is underground, so humans cannot access much of it.
This bubble is from all the rivers and lakes on the planet. These surface-water sources provide most of the water that people and other life on Earth need daily.
This sphere has a volume of approximately 22,339 mi3. This sphere measures 34.9 miles in diameter. Imagine an almost 35 mile-tall bubble. For comparison, Lake Michigan’s average depth is only 300 feet.
97% of the water on Earth’s surface is oceanic saline water. People have the freshwater resources they need to survive daily, including water that falls from the sky and flows into rivers, streams, lakes, and groundwater.
Noticing where water is on the Earth’s surface is relatively easy; for example, how rain fills up lakes and rivers. The unseen water beneath our feet is also vital to our lives.
How can we account for rivers flowing after weeks without rain? How do we account for the water that flows down our driveways when it isn’t raining? Our water supply is far more complex than just surface water.
Although only the Earth’s surface water is apparent to many people, the ground holds more freshwater than what is available in free-flowing liquid form.
Some of the water that flows into rivers results from seepage from groundwater into riverbeds. Rainwater drains continuously into the ground and recharges ground reservoirs.
In turn, water in these ground sources continually recharges rivers through seepage.
Humans make use of both types of water, surface water and groundwater. The United States used approximately 275 billion gallons of surface water daily in 2010 and 79.3 million gallons of groundwater daily.
Groundwater is essential, even though it is used more to provide drinking water and irrigate crops. However, surface water is vital because it helps keep lakes and rivers full.
It also supplies water to people living in areas where there is little water, like in the deserts of the west. People would rather be playing golf in Palm Springs, California, than sand-surfing.
- If all atmospheric water, groundwater, lakes and rivers, glaciers, ice caps, and oceans were put into a ball, the ball would have a diameter of about 860 miles. This is about the same distance as Topeka, Kansas to Salt Lake City, Utah. The ball of all the water would have a total volume of 332.5 million cubic miles (mi3). 1 mi3 is slightly more than 1.1 trillion gallons.
- On average, at any moment, there is approximately 3100 mi3 of atmospheric water. Most of it is water vapor. It would only cover about 1 inch if all of it fell as precipitation.
- The 48 contiguous states (lower 48 US) receive approximately 4 mi3 precipitation each day.
- Approximately 280 mi3 of water evaporates or is absorbed into the atmosphere every day.
- If all the water in the world were poured onto the United States contiguously, it would cover the country to a depth of approximately 107 miles.
- The ground holds more freshwater than rivers and lakes, which is why there is so much of it. The Earth holds more than 2,000,000 mi3 of freshwater, most of it within one-half mile of the surface. The majority of this freshwater is found in the 7,000,000 mi3 of water held within glaciers and icecaps located mainly in the polar regions, and Greenland.
A quintillion (Q) is this extraordinarily large number: 1,000,000,000,000,000,000 (1 followed by 18 zeros)!
In quintillions of gallons of water, the ocean holds just a nudge over 350. Water infiltrates the ocean by rivers and melting ice and escapes from the ocean through evaporation.
The ocean’s average depth is approximately 12,100 feet. This is a depth of about 2.3 miles, and it is affected by the size and the age of the ocean. The global ocean’s deepest basin is in the Pacific.
The Volkswagen ROV was built to withstand pressures at depths of 13,100ft. With more than 6,000 PSI (pounds per square foot of force), that’s about 2.5 miles deep.
The majority of the planet’s water lies on its surface. The ocean is spread out across over 70% of the planet’s surface. That equates to around 139 million miles of salty blue.
We have Mars maps that are sharper and clearer than the maps we have of the ocean. The GEBCO Seabed Project of the Nippon Foundation is attempting to completely map Earth’s ocean floor by 2030.
So far, only a fifth of the entire ocean floor in the world has been mapped. This equates to having a map only twice Australia’s size.
Hydrothermal vents are found in the Earth’s seafloor and spew mineral-rich water – similar to geysers – that is powered by volcanoes.
Hydrothermal vents’ temperatures can reach a staggering 700°F, yet the seawater in the vent won’t boil due to the tremendous pressure exerted by the miles of seawater pressing down on these special features.
The deepest point lies at a depth greater than 35,000 feet below the surface of the ocean. It is a point along the Mariana Trench called “Challenger Deep.”
For every 33 feet in depth, the pressure increases by one atmosphere. The ocean reaches its greatest depth in the Mariana Trench.
There, the pressure exceeds 16,000 PSI. Humans, in comparison, experience a sea-level surface air pressure of only 14.7 PSI.
The planet’s longest mountain range goes on for over 40,000 miles. There’s little hope of seeing this unique formation – called the Mid Ocean Ridge – because over 90% of it is below water.
In short, a lot. Photosynthetic microorganisms called phytoplankton transform sunlight into oxygen. They do this using photosynthesis just like land plants.
It is thought that some 50% to 80% of the Earth’s oxygen resources originate in its oceans.