How do ocean currents work? - Jennifer Verduin

Summary

In 1992, a storm scattered 28,000 rubber ducks across the North Pacific, inadvertently aiding oceanographic research. These ducks' global distribution has helped scientists chart ocean currents, which are influenced by wind, tides, water density changes, and Earth's rotation. Ocean currents are categorized into surface and deep ocean currents, with surface currents forming gyres due to the Coriolis Effect. Deep currents, driven by water density, establish thermohaline circulation, contributing to the Global Conveyor Belt. This conveyor belt, moving slowly and carrying nutrients, is crucial for marine life and global climate. However, rising temperatures threaten its pace, with potential severe impacts on weather systems.

Takeaways

• 🌊 In 1992, a storm caused 28,000 rubber ducks to be swept into the North Pacific, which researchers later used to study ocean currents.
• 💨 Ocean currents are influenced by wind, tides, water density changes, and Earth's rotation, with the ocean floor and shoreline affecting their speed and direction.
• 🔄 There are two main types of ocean currents: surface currents affecting the top 10% of the ocean's water, and deep ocean currents affecting the remaining 90%.
• 🌀 Surface currents near the shore are driven by wind and tides, while in the open ocean, wind is the primary force, creating gyres that move in different directions in each hemisphere.
• 🌀 The Coriolis Effect, due to Earth's rotation, causes wind patterns to form loop-like gyres, which in turn push ocean currents into the same rotating patterns.
• 🌡 Deep ocean currents are driven by density changes in seawater, with colder, saltier water sinking and warmer water rising, creating a vertical current known as thermohaline circulation.
• 🌍 The combination of thermohaline circulation and surface currents forms the Global Conveyor Belt, which moves slowly around the globe, carrying nutrients vital for ocean life.
• ⏳ The Global Conveyor Belt is incredibly slow, taking a thousand years for a drop of water to complete its journey.
• 📉 Rising sea temperatures may be causing the conveyor belt to slow down, which could have significant impacts on weather systems, particularly across the Atlantic.
• ❓ The potential consequences of the conveyor belt slowing down or stopping are unknown, emphasizing the need for continued research to predict and prepare for such changes.
• 🔬 Continued study of ocean currents and the forces that shape them is essential for accurate forecasting and preparation against potential climate disruptions.

Q & A

What event in 1992 led to the discovery of ocean currents by researchers?

In 1992, a cargo ship carrying bath toys got caught in a storm, and 28,000 rubber ducks and other toys were swept into the North Pacific. The dispersion of these toys across the globe allowed researchers to study and chart ocean currents.

What are the main factors that drive ocean currents?

Ocean currents are driven by the wind, tides, changes in water density, and the rotation of the Earth. Additionally, the topography of the ocean floor and shoreline can modify these motions.

How do surface currents and deep ocean currents differ in their control over ocean water?

Surface currents control the motion of the top 10 percent of the ocean's water, while deep-ocean currents mobilize the other 90 percent.

What is the relationship between surface currents and deep ocean currents?

Surface and deep ocean currents influence each other in an intricate way, with surface currents being affected by wind and tides, and deep ocean currents being driven by changes in seawater density.

How do wind and tides affect surface currents near the shore?

Near the shore, surface currents are driven by both the wind and tides, which cause water to move back and forth as the water level rises and falls.

What is the major force behind surface currents in the open ocean?

In the open ocean, wind is the major force behind surface currents, as it drags the top layers of water and creates a chain reaction that affects deeper layers.

What are gyres and how do they form?

Gyres are large loops of surface currents that form patterns all over the Earth. They travel clockwise in the northern hemisphere and counter-clockwise in the southern hemisphere due to the Earth's rotation and the Coriolis Effect.

How does the Coriolis Effect influence the direction of gyres?

The Coriolis Effect causes the wind patterns that give rise to gyres to deflect, resulting in clockwise movement in the northern hemisphere and counter-clockwise movement in the southern hemisphere.

What is the primary driver of deep ocean currents?

Deep ocean currents are primarily driven by changes in the density of seawater, which is influenced by temperature and salinity.

What is the Global Conveyor Belt and how does it function?

The Global Conveyor Belt is a winding loop formed by the combination of thermohaline circulation of deep water and wind-driven surface currents. It moves slowly around the globe, transporting nutrients from the depths to the surface, supporting marine life.

What potential impact could the slowing of the Global Conveyor Belt have on weather systems?

If the Global Conveyor Belt slows down or stops due to rising sea temperatures, it could disrupt weather systems, particularly on both sides of the Atlantic, with unpredictable consequences.

Why is it important to continue studying ocean currents?

Studying ocean currents is crucial for understanding and forecasting weather patterns, climate change impacts, and the health of marine ecosystems.

Outlines

00:00

🌊 Ocean Currents and the Rubber Duck Phenomenon

In 1992, a storm led to the loss of 28,000 rubber ducks and other bath toys from a cargo ship into the North Pacific. Instead of remaining together, these ducks dispersed globally, providing researchers with a unique opportunity to study ocean currents. Ocean currents are influenced by wind, tides, water density changes, and Earth's rotation. They are shaped by the ocean floor and shoreline, resulting in variations in speed and direction. The two primary types of currents are surface and deep ocean currents, with surface currents affecting the upper 10% of water and deep currents the remaining 90%. These currents interact in complex ways, with surface currents driven by wind and tides near the shore and by wind alone in the open ocean. Surface currents form gyres, large loops that rotate clockwise in the northern hemisphere and counter-clockwise in the southern due to the Coriolis Effect, which is caused by Earth's rotation. Deep ocean currents, on the other hand, are driven by seawater density changes, forming a vertical current known as thermohaline circulation. Together, these currents create the Global Conveyor Belt, which slowly circulates water and nutrients around the globe, supporting marine life. However, climate change threatens this system, as rising sea temperatures may slow down the conveyor belt, with potentially severe impacts on weather systems.

Keywords

💡Ocean Currents

Ocean currents are the continuous movement of ocean water in a specific direction, driven by various forces including the wind, tides, changes in water density, and the Earth's rotation. In the context of the video, ocean currents play a crucial role in distributing heat around the globe and are central to understanding the movement of the rubber ducks, which serve as a real-world example of how these currents work. The video explains that ocean currents are divided into surface and deep ocean currents, each with distinct characteristics and behaviors.

💡Surface Currents

Surface currents are the movements of the top 10 percent of the ocean's water, primarily influenced by wind and tides. They are significant in the video's narrative as they are responsible for the dispersion of the rubber ducks across the globe. The script mentions that in the open ocean, wind is the major force behind surface currents, demonstrating how wind can drag the top layers of water and affect water as deep as 400 meters.

💡Deep Ocean Currents

Deep ocean currents are the movements that mobilize the bottom 90 percent of the ocean's water and are mainly driven by changes in the density of seawater. The video script explains that as water moves towards the poles, it becomes colder and saltier, leading to a higher density that causes it to sink. This process sets up a vertical current known as thermohaline circulation, which is a key component of the global conveyor belt discussed in the video.

💡Gyres

Gyres are large systems of rotating ocean currents that form closed, loop-like patterns. The video script describes how these gyres travel in different directions in the northern and southern hemispheres due to the Coriolis Effect, which is a result of the Earth's rotation influencing wind patterns. Gyres are important in understanding the dispersal of the rubber ducks and the broader implications for ocean circulation and climate.

💡Coriolis Effect

The Coriolis Effect is the apparent deflection of the path of an object moving in a rotating system. In the video, it is mentioned as the reason why surface currents form gyres that rotate clockwise in the northern hemisphere and counter-clockwise in the southern hemisphere. This effect is critical in shaping the direction of ocean currents and, by extension, the paths that the rubber ducks take.

💡Thermohaline Circulation

Thermohaline circulation is a vertical ocean current driven by differences in water density, primarily caused by variations in temperature and salinity. The video script explains how cold, salty water becomes denser and sinks, while warmer surface water rises, creating a cycle that moves water and nutrients throughout the ocean. This concept is integral to understanding the deep ocean currents and their role in the global conveyor belt.

💡Global Conveyor Belt

The Global Conveyor Belt, as mentioned in the script, is a term used to describe the complex system of ocean currents that circulate water around the Earth. It is formed by the combination of thermohaline circulation and wind-driven surface currents. The video emphasizes the slow movement of this current, which can take a thousand years for a drop of water to complete the journey, and its importance in distributing nutrients and affecting weather systems.

💡Bath Toys

In the video script, bath toys, specifically rubber ducks, are used as a case study to illustrate the behavior of ocean currents. The story of the cargo ship that lost 28,000 rubber ducks during a storm provides a tangible example of how objects can be dispersed by ocean currents. The ducks' paths have helped researchers chart and better understand these currents, making 'bath toys' a key concept in the video's exploration of oceanographic phenomena.

💡Density

Density, in the context of the video, refers to the mass per unit volume of a substance, and it is a critical factor in the movement of deep ocean currents. The script explains how changes in the density of seawater, due to cooling and increased salt concentration, cause water to sink and initiate thermohaline circulation. Understanding density is essential to grasping how deep ocean currents are formed and maintained.

💡Rising Sea Temperatures

The video script mentions rising sea temperatures as a factor that could potentially slow down the global conveyor belt. This is significant because it suggests that climate change could have profound effects on ocean currents, which in turn could disrupt weather systems and the distribution of nutrients in the ocean. The mention of rising sea temperatures highlights the potential consequences of environmental changes on the complex systems that govern our planet's climate.

Highlights

In 1992, a cargo ship lost 28,000 rubber ducks in the North Pacific, which have since dispersed globally.

The dispersed rubber ducks have been used by researchers to study ocean currents.

Ocean currents are influenced by wind, tides, water density changes, and Earth's rotation.

Ocean currents are modified by the ocean floor and shoreline topography, affecting their speed and direction.

There are two main types of ocean currents: surface and deep ocean currents.

Surface currents affect the top 10% of ocean water, while deep ocean currents the remaining 90%.

Surface and deep ocean currents interact in a complex manner, influencing the entire ocean's movement.

Near shores, surface currents are driven by wind and tides.

In the open ocean, wind is the primary force behind surface currents.

Wind drags the top ocean layers, affecting water as deep as 400 meters.

Global surface currents form gyres, rotating clockwise in the north and counter-clockwise in the south.

The Coriolis Effect, due to Earth's rotation, influences wind and ocean current patterns.

Deep ocean currents are driven by changes in seawater density, particularly related to temperature and salinity.

Thermohaline circulation is a vertical current formed by the sinking of cold, salty water.

The Global Conveyor Belt is formed by the combination of thermohaline circulation and surface currents.

The Global Conveyor Belt carries nutrients essential for ocean food chains.

Rising sea temperatures may be slowing down the Global Conveyor Belt, with unknown long-term effects.

Continued study of ocean currents is crucial for accurate weather forecasting and preparation.

Transcripts

In 1992,

a cargo ship carrying bath toys got caught in a storm.

Shipping containers washed overboard,

and the waves swept 28,000 rubber ducks and other toys into the North Pacific.

But they didn’t stick together.

Quite the opposite–

the ducks have since washed up all over the world,

and researchers have used their paths

to chart a better understanding of ocean currents.

Ocean currents are driven by a range of sources:

the wind, tides, changes in water density,

and the rotation of the Earth.

The topography of the ocean floor and the shoreline modifies those motions,

causing currents to speed up,

slow down, or change direction.

Ocean currents fall into two main categories:

surface currents and deep ocean currents.

Surface currents control the motion

of the top 10 percent of the ocean’s water,

while deep-ocean currents mobilize the other 90 percent.

Though they have different causes,

surface and deep ocean currents influence each other

in an intricate dance that keeps the entire ocean moving.

Near the shore,

surface currents are driven by both the wind and tides,

which draw water back and forth as the water level falls and rises.

Meanwhile, in the open ocean, wind is the major force behind surface currents.

As wind blows over the ocean,

it drags the top layers of water along with it.

That moving water pulls on the layers underneath,

and those pull on the ones beneath them.

In fact, water as deep as 400 meters

is still affected by the wind at the ocean’s surface.

If you zoom out to look at the patterns of surface currents all over the earth,

you’ll see that they form big loops called gyres,

which travel clockwise in the northern hemisphere

and counter-clockwise in the southern hemisphere.

That’s because of the way the Earth’s rotation

affects the wind patterns that give rise to these currents.

If the earth didn’t rotate,

air and water would simply move back and forth

between low pressure at the equator

and high pressure at the poles.

But as the earth spins,

air moving from the equator to the North Pole is deflected eastward,

and air moving back down is deflected westward.

The mirror image happens in the southern hemisphere,

so that the major streams of wind

form loop-like patterns around the ocean basins.

This is called the Coriolis Effect.

The winds push the ocean beneath them into the same rotating gyres.

And because water holds onto heat more effectively than air,

these currents help redistribute warmth around the globe.

Unlike surface currents,

deep ocean currents are driven primarily by changes in the density of seawater.

As water moves towards the North Pole,

it gets colder.

It also has a higher concentration of salt,

because the ice crystals that form trap water while leaving salt behind.

This cold, salty water is more dense,

so it sinks,

and warmer surface water takes its place,

setting up a vertical current called thermohaline circulation.

Thermohaline circulation of deep water and wind-driven surface currents

combine to form a winding loop called the Global Conveyor Belt.

As water moves from the depths of the ocean to the surface,

it carries nutrients that nourish the microorganisms

which form the base of many ocean food chains.

The global conveyor belt is the longest current in the world,

snaking all around the globe.

But it only moves a few centimeters per second.

It could take a drop of water a thousand years to make the full trip.

However, rising sea temperatures are causing the conveyor belt

to seemingly slow down.

Models show this causing havoc with weather systems

on both sides of the Atlantic,

and no one knows what would happen if it continues to slow

or if it stopped altogether.

The only way we’ll be able to forecast correctly and prepare accordingly

will be to continue to study currents and the powerful forces that shape them.