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0 / 31 Fotos
Types of ocean currents
- When we think about ocean currents, we tend to think about the ones that are visible to the naked eye. Tidal currents, for example, occur close to shore and are influenced by the sun and the moon.
© Shutterstock
1 / 31 Fotos
Slow currents
- There are also surface currents, which are influenced by the wind. However, many of us ignore the much slower currents that occur from the surface of the ocean to its floor.
© Shutterstock
2 / 31 Fotos
Thermohaline circulation
- These are driven by changes in the saltiness and temperature of the oceanwater, in a process called thermohaline circulation.
© Shutterstock
3 / 31 Fotos
AMOC
- There are various complex systems that carry these slow currents, but the most important one is the Atlantic Meridional Overturning Circulation (AMOC).
© Shutterstock
4 / 31 Fotos
Importance
- The AMOC is responsible for bringing warmth to various parts of the globe. Indeed, it is vital in regulating the temperature of Earth.
© Shutterstock
5 / 31 Fotos
How it works
- So, how exactly does it work? The process starts when the warm water near the surface of the ocean moves northwards towards the North Pole.
© Shutterstock
6 / 31 Fotos
Sea ice
- As the water moves northwards it cools, eventually forming sea ice. As the sea ice forms, it leaves salt in the water, meaning the water becomes denser.
© Shutterstock
7 / 31 Fotos
Sinking effect
- The cool, dense water then sinks deep into the ocean, where it gradually spreads southwards below the ocean surface.
© Shutterstock
8 / 31 Fotos
Upwelling
- Eventually the cool, dense water gets pulled back up to the surface in a process called "upwelling," and the circulation process is complete.
© Shutterstock
9 / 31 Fotos
Scale
- This entire circulation process happens on a massive scale: the AMOC is estimated to move 17 million cubic meters of warm water north every second.
© Shutterstock
10 / 31 Fotos
Distributing heat
- This distributes around 1.2 petawatts of heat, which is equivalent to the amount of energy that flows through one million power stations.
© Shutterstock
11 / 31 Fotos
Speed
- However, the entire circulation cycle of the AMOC is very slow. It is estimated to take 1,000 years for a single cubic meter of water to make the full journey.
© Shutterstock
12 / 31 Fotos
Very important
- Although it may be slow, the circulation process of the AMOC is nonetheless very important: it is this process that ensures the world's oceans are continuously mixed.
© Shutterstock
13 / 31 Fotos
Controlling the climate
- Without this process, there would be no way to distribute heat and energy properly around the Earth, and we would not experience climate as we know it.
© Shutterstock
14 / 31 Fotos
Marine ecosystems
- The AMOC also plays an important role in helping control and manage the planet's marine ecosystems.
© Shutterstock
15 / 31 Fotos
Monitoring the AMOC
- Since 2004, oceanographers have been monitoring the AMOC to see if it changes. A key question is whether the AMOC can be expected to slow down in years to come.
© Shutterstock
16 / 31 Fotos
Variations year over year
- So far, measurements have shown that the AMOC does vary from year to year. It is likely that these variations have had an impact on the weather in certain places.
© Shutterstock
17 / 31 Fotos
Impossible to make predictions
- However, it is too soon to say whether there are any long-term trends: there is simply not enough data.
© Shutterstock
18 / 31 Fotos
Pre-2004
- Before 2004, the AMOC was only measured a few times, and to go back even further researchers have to rely on indirect evidence, such as sediments on the ocean floor.
© Shutterstock
19 / 31 Fotos
Most likely
- While they cannot be certain about the details, experts do believe that there were probably some drastic changes in the AMOC in the past (for example, around the time of the last Ice Age).
© Shutterstock
20 / 31 Fotos
Going forward - In terms of how the AMOC may change in coming decades, models suggest that it will weaken if greenhouse gases in the atmosphere continue to increase.
© iStock
21 / 31 Fotos
Warmer ocean surface
- This is because if greenhouse gases continue to increase and the atmosphere continues to warm, the surface of the ocean will retain more of its heat.
© Shutterstock
22 / 31 Fotos
Warmer ocean water - Combined with increased rainfall and melting ice, which makes for fresher ocean water, the warmer surface temperature of the ocean will make for warmer water.
© Getty Images
23 / 31 Fotos
Impact on sinking water
- As a result, the sinking effect of the water will be reduced, and the AMOC will become weakened. In fact, some experts are concerned that it may completely collapse.
© Getty Images
24 / 31 Fotos
IPCC guidance
- However, according to the IPCC Sixth Assessment Report (AR6) WGI report, there is "medium confidence" that there will not be an abrupt collapse before 2100.
© Shutterstock
25 / 31 Fotos
Impact of a weakened AMOC
- Even if the AMOC does not collapse, a weakened circulation system could still have far-reaching impacts for the climate.
© Shutterstock
26 / 31 Fotos
Example - For example, if the planet continues to warm, the freshwater from melting ice at the poles could cause the rain belt in South Africa to shift.
© Shutterstock
27 / 31 Fotos
Widespread drought - If this happens, it could mean drought for millions of people. Another potential consequence would be rising sea levels across the US East Coast.
© NL Beeld
28 / 31 Fotos
Final thoughts
- As previously mentioned, research scientists do not yet have enough evidence to predict whether the AMOC will weaken or even collapse over the course of the 21st century.
© NL Beeld
29 / 31 Fotos
One thing's for sure
- However, one thing is certain: if either one of those scenarios does in fact occur, there will be far-reaching consequences for the climate as we know it. Sources: (National Ocean Service) (Met Office) (BBC)
© Shutterstock
30 / 31 Fotos
© Shutterstock
0 / 31 Fotos
Types of ocean currents
- When we think about ocean currents, we tend to think about the ones that are visible to the naked eye. Tidal currents, for example, occur close to shore and are influenced by the sun and the moon.
© Shutterstock
1 / 31 Fotos
Slow currents
- There are also surface currents, which are influenced by the wind. However, many of us ignore the much slower currents that occur from the surface of the ocean to its floor.
© Shutterstock
2 / 31 Fotos
Thermohaline circulation
- These are driven by changes in the saltiness and temperature of the oceanwater, in a process called thermohaline circulation.
© Shutterstock
3 / 31 Fotos
AMOC
- There are various complex systems that carry these slow currents, but the most important one is the Atlantic Meridional Overturning Circulation (AMOC).
© Shutterstock
4 / 31 Fotos
Importance
- The AMOC is responsible for bringing warmth to various parts of the globe. Indeed, it is vital in regulating the temperature of Earth.
© Shutterstock
5 / 31 Fotos
How it works
- So, how exactly does it work? The process starts when the warm water near the surface of the ocean moves northwards towards the North Pole.
© Shutterstock
6 / 31 Fotos
Sea ice
- As the water moves northwards it cools, eventually forming sea ice. As the sea ice forms, it leaves salt in the water, meaning the water becomes denser.
© Shutterstock
7 / 31 Fotos
Sinking effect
- The cool, dense water then sinks deep into the ocean, where it gradually spreads southwards below the ocean surface.
© Shutterstock
8 / 31 Fotos
Upwelling
- Eventually the cool, dense water gets pulled back up to the surface in a process called "upwelling," and the circulation process is complete.
© Shutterstock
9 / 31 Fotos
Scale
- This entire circulation process happens on a massive scale: the AMOC is estimated to move 17 million cubic meters of warm water north every second.
© Shutterstock
10 / 31 Fotos
Distributing heat
- This distributes around 1.2 petawatts of heat, which is equivalent to the amount of energy that flows through one million power stations.
© Shutterstock
11 / 31 Fotos
Speed
- However, the entire circulation cycle of the AMOC is very slow. It is estimated to take 1,000 years for a single cubic meter of water to make the full journey.
© Shutterstock
12 / 31 Fotos
Very important
- Although it may be slow, the circulation process of the AMOC is nonetheless very important: it is this process that ensures the world's oceans are continuously mixed.
© Shutterstock
13 / 31 Fotos
Controlling the climate
- Without this process, there would be no way to distribute heat and energy properly around the Earth, and we would not experience climate as we know it.
© Shutterstock
14 / 31 Fotos
Marine ecosystems
- The AMOC also plays an important role in helping control and manage the planet's marine ecosystems.
© Shutterstock
15 / 31 Fotos
Monitoring the AMOC
- Since 2004, oceanographers have been monitoring the AMOC to see if it changes. A key question is whether the AMOC can be expected to slow down in years to come.
© Shutterstock
16 / 31 Fotos
Variations year over year
- So far, measurements have shown that the AMOC does vary from year to year. It is likely that these variations have had an impact on the weather in certain places.
© Shutterstock
17 / 31 Fotos
Impossible to make predictions
- However, it is too soon to say whether there are any long-term trends: there is simply not enough data.
© Shutterstock
18 / 31 Fotos
Pre-2004
- Before 2004, the AMOC was only measured a few times, and to go back even further researchers have to rely on indirect evidence, such as sediments on the ocean floor.
© Shutterstock
19 / 31 Fotos
Most likely
- While they cannot be certain about the details, experts do believe that there were probably some drastic changes in the AMOC in the past (for example, around the time of the last Ice Age).
© Shutterstock
20 / 31 Fotos
Going forward - In terms of how the AMOC may change in coming decades, models suggest that it will weaken if greenhouse gases in the atmosphere continue to increase.
© iStock
21 / 31 Fotos
Warmer ocean surface
- This is because if greenhouse gases continue to increase and the atmosphere continues to warm, the surface of the ocean will retain more of its heat.
© Shutterstock
22 / 31 Fotos
Warmer ocean water - Combined with increased rainfall and melting ice, which makes for fresher ocean water, the warmer surface temperature of the ocean will make for warmer water.
© Getty Images
23 / 31 Fotos
Impact on sinking water
- As a result, the sinking effect of the water will be reduced, and the AMOC will become weakened. In fact, some experts are concerned that it may completely collapse.
© Getty Images
24 / 31 Fotos
IPCC guidance
- However, according to the IPCC Sixth Assessment Report (AR6) WGI report, there is "medium confidence" that there will not be an abrupt collapse before 2100.
© Shutterstock
25 / 31 Fotos
Impact of a weakened AMOC
- Even if the AMOC does not collapse, a weakened circulation system could still have far-reaching impacts for the climate.
© Shutterstock
26 / 31 Fotos
Example - For example, if the planet continues to warm, the freshwater from melting ice at the poles could cause the rain belt in South Africa to shift.
© Shutterstock
27 / 31 Fotos
Widespread drought - If this happens, it could mean drought for millions of people. Another potential consequence would be rising sea levels across the US East Coast.
© NL Beeld
28 / 31 Fotos
Final thoughts
- As previously mentioned, research scientists do not yet have enough evidence to predict whether the AMOC will weaken or even collapse over the course of the 21st century.
© NL Beeld
29 / 31 Fotos
One thing's for sure
- However, one thing is certain: if either one of those scenarios does in fact occur, there will be far-reaching consequences for the climate as we know it. Sources: (National Ocean Service) (Met Office) (BBC)
© Shutterstock
30 / 31 Fotos
AMOC: the ocean current that regulates our weather
And how climate change may affect it
© Shutterstock
Most people do not give a lot of thought to ocean currents until they are at the beach. Of course, nobody wants to be awoken from a beach slumber by a rushing wave that drenches all of their belongings. However, ocean currents are much more than a mere nuisance. In fact, there is one very important, long-term ocean current that plays an important role in regulating the Earth's climate.
Curious? Check out this gallery to find out more.
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