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Ocean Salinity: How Much Salt is in Oceans?

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Ocean Salinity

How Much Salt is in Oceans?

Imagine you’re stranded on a raft in the middle of the ocean. All this water. But nothing fresh to drink.

Oceans are salty because runoff transports minerals and salts from the surface. When the ocean evaporates from heat, salt remains in the ocean and water rises.

Even though rainwater washes minerals and salts into rivers and lakes, they are mostly freshwater. This is because their minerals get washed away and transported to an outlet at the nearest ocean.

So unlike salty oceans, lakes, and rivers constantly have the minerals washed away.

How much total volume is salt water?

5 Oceans Map

Imagine you’re stranded on a raft in the middle of the ocean. You see nothing but open water. But none of it is freshwater to drink. If you compare saltwater and freshwater:

SALT WATER: about 97.2% is not suitable for drinking because it has salt in it.
FRESH WATER: If we sum up all the sources of freshwater, about 2.8% of water on Earth is freshwater.

The majority of saltwater is from the 5 oceans that surround continents. And the average depth of oceans is 2.7 kilometers so water volume is about 1,338,000,000 cubic kilometers.

Oceans are the foundation of the water cycle. Water moves continuously in nature in three stages: evaporation, condensation, and surface runoff.

Ocean currents are like giant conveyor belts moving huge amounts of water all the time. While wind drives surface ocean currents from the Coriolis effect, temperature and salt gradients mostly influence deep ocean currents.

What is the distribution of fresh and salt water?

Earth is unique because of how much water it stores. But the distribution of the total volume of water differs disproportionately for fresh and salt water.

If you crunch the numbers, Earth holds about 326 million trillion gallons (326,000,000,000,000,000,000 gallons) of water. As already mentioned, most of the water is saltwater. Just a small portion of it is freshwater.

Here’s the percentage and total (in gallons) for the global water distribution of all sources of water.

SourceGallonsPercentage
Oceans316,872,000,000,000,000,00097.2%
Glaciers6,846,000,000,000,000,0002.1%
Groundwater2,119,000,000,000,000,0000.65%
Lakes55,420,000,000,000,0000.017%
Soil Moisture16,300,000,000,000,0000.005%
Streams, wetlands and swamps3,260,000,000,000,0000.001%
Total326,000,000,000,000,000,000100%

Ocean Salinity: How Much Salt is in Oceans?

Our oceans are an important part of our planet. It sustains life as well as regulates the climate and provides a service by absorbing CO2. Ocean salinity is the amount of salt in the ocean, which has an impact on ocean temperature, sea level, and climate change.

Do you want to study more about this topic and other concepts of oceanography? If you do, there are a lot of career opportunities there. These online courses can help you get started.

If you have any questions or feedback about ocean science, please use the comment form below to let us know what is on your mind.

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