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Can Ocean Water Freeze? Check out the Facts!

The sea is a massive body of saltwater covering 71% of the world’s surface. The ocean’s temperature is affected by altitude; the higher the altitude, the less light the ocean receives. The North and South Pole receive 40% of the equator’s heat as it moves with ocean currents. The temperature can range from 86°F (30°C) in tropical regions to 28°F (-2°C) at the poles. The average temperature of the ocean is about 38.3°F (3.5°C).

Ocean water can freeze, but under certain conditions, the main one being the temperature. The high concentration of salt causes the freezing point to decrease to 28.4°F (-2°C). Other factors affecting the ocean from freezing include its high volume, ocean currents, and the Earth’s internal heating.

The ocean water takes much longer to freeze compared to freshwater due to a few reasons. There are also different places on the Earth where ocean water will freeze and places where the ice is not seawater but freshwater coming off the land that freezes.

How Does Ocean Water Freeze?

The ocean can freeze, but only when it is cold enough; the North Pole known as the Arctic is a giant slab of frozen ocean water. Other places like the South Pole, Canada, and Greenland do not have frozen ocean water but instead are made of compacted snow. 

This ice is formed because freshwater found in the air freezes, which then falls on the land. When it is a freezing season, it will stop snow from melting; causing it to build up over time and compact together, forming ice known as a glacier. Gravity will cause the compacted ice to move downhill into the ocean forming an ice shelf. 

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When the ice shelf is in the water, the edges of it will start to crumble into smaller icebergs, floating and moving as the currents take it. Due to this process, icebergs, glaciers, and ice shelves found in the ocean are freshwater and not ocean water. 

When ocean water freezes, it forms into thin sheets of sea ice or pack ice. As the thin layer of ice is created, it will cool the water beneath it, freeze, thickening it. Sea ice is an enemy to ships as they struggle to move through it, causing damage; this is not the case for ice breaker ships that can push through easily. Only about 15% of the ocean is made up of ice during some seasons. This accounts for about 10 million square miles of ice in the sea.

Ocean water will stay in a liquid form even if it snows on land or freshwater freezes. The temperature of ocean water needs to be colder than freshwater for it to freeze. Freshwater freezes at a temperature of 32°F (0°C), and ocean water freezes at a temperature of 28.4°F (-2°C). There are four main reasons that influence the freezing point of seawater. 

How Does Salt Affect The Oceans Ability To Freeze?

When a substance is added to water, it can either increase or decrease its freezing point. The high salt concentration in the ocean causes the water molecules to be displaced; there is about 35g of salt in 1000 units of water. The salt causes the freezing point of the seawater to decrease from 32°F (0°C) of freshwater to 28.4°F (-2°C). 

This is where people got the idea to put saltwater on their sidewalks and walkways; it decreases the freezing temperature causing the ice to melt or prevents ice from forming. It is not the only thing needed for seawater to freeze; other things influence it as well. When seawater freezes, the salt separates, and only freshwater forms into ice crystals. The salt molecules are pushed beneath the ice when it is being formed. 

How Do The Oceans Currents Affect It Freezing?

Ocean currents are the movement of ocean water and waves’ formation; this is caused by the moon’s gravitational pull, the thermals convection, and spinning of the Earth. This constant movement of water prevents the water molecules from freezing and forming solid ice crystals. The ocean’s motion helps it retain heat, and the current moves warm water from the equator into colder regions reducing the chance of freezing.

We know that the wind and moon cause ocean currents, but the ice formed from ocean water and freshwater from land can also cause deep water currents. As ice is created, it causes the water beneath it to become saltier, denser which will then sink. The oceans water becomes denser as it gets colder, while freshwater is far above its freezing point where it is at its highest density. 

The moon and wind can cause strong currents in the ocean

As this water moves down, less dense water moves to the surface; this water will cool and become salty, causing it to sink. This causes deep-sea currents due to water movement, known as thermohaline circulation or commonly referred to as global ocean conveyer belt. These currents can move all over the world.

How Does The Volume Of The Ocean Impact Its Ability To Freeze?

The larger the water volume, the longer it will take to freeze; this is because it has to get rid of more heat. If you put a small container with 50ml of water, it will freeze much quicker than half a gallon jug of water. Let’s look at the surface area to the volume of water, as it is more important than the volume alone. 

The rate of heat loss will escape quicker from a larger surface area and low volume of water compared to a small surface area to the volume and depth of water. A puddle of water that is relatively shallow with a larger surface area to its volume will freeze quicker than a deep pool with a smaller surface area to its volume. Due to this, the ocean will take a long time to freeze due to its immense volume and depth.

How Does The Internal Temperature Of The Earth Effect The Ocean Freezing?

The Earth’s core is extremely hot as it is made of nuclear decay of elements; it has a liquid molten outer core and solid iron inner core. As you move deeper into the Earth’s surface, the hotter it gets due to the Earth’s own heat source. The Earth’s continents are much higher than the ocean floor, which is why the ocean floor is hotter as the crust is much thinner. 

The Earth’s internal heat escapes through the ocean floor, which will be warmer than the surface of the ocean. The Earth’s internal heat can be evident from hot springs and volcanos where lava flows onto the Earth’s surface. As the Earth’s internal heating source heats the ocean, this will reduce its ability to freeze in specific areas compared to others.

How Has Global Warming Affected Ocean Water Freezing?

With global warming, ocean temperatures are changing, the amount of heat that the ocean is absorbing has increased, which is increasing every year. Due to the ocean water’s temperature rising, it begins the cycle of warming and melting. Ice takes longer to form, resulting in less being formed in winter and fall, while in spring, it melts much quicker. 

The surface of oceans is warming up by about 24% quicker than a few decades ago. The changes in ice formation have an effect on ocean circulation, which further affects the global climate. With less ice forming, there will be fewer bright surfaces which help reflect the sunlight into the atmosphere. 

This is important at the Poles because the reflection of light helps keep these regions cool; if there is less ice, then the temperatures will increase in these areas. Rising temperatures of the ocean significantly affect marine life, especially ones that live close to the surface. This includes whales, fish, plankton, and coral that are very sensitive to temperature changes.

Scientists have also predicted that warming seas can cause storms to become stronger, like hurricanes and tropical cyclones.  Warmer seas take up more space compared to cold seas; this causes the sea levels to rise. Each year the ocean levels have been increased by 0.03 inches. 


It is fascinating to understand how the ice in the ocean is made. Some of it is made from freshwater on land, while others, such as in the South Pole, are from ocean water cooling enough to produce ice. 

Ice is vital for regulating temperatures on Earth and in the sea. We also need sea ice for land animals as they use it to catch food; for example, polar bears need it to rest while catching seals.

As a society, we can do certain things in our everyday lives to reduce or slow down global warming. This includes things like reducing electricity use, reducing food waste, and reducing the use of plastics.

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