Carbon Cycle 3

Question 1

What are phytoplankton?

Answer 1

Microscopic organisms that photosynthesize

They take in carbon and turn it into organic matter.

Question 2

Phytoplankton account for around what percentage of the world’s photosynthetic biomass?

Answer 2

1%

Despite this small percentage, they contribute almost half of the total primary production.

Question 3

Phytoplankton are the base of the marine food web. What happens when they get eaten?

Answer 3

Carbon is passed through the food chain

This process is crucial for the transfer of energy in marine ecosystems.

Question 4

What gas is released back into the water as phytoplankton respire?

Answer 4

CO2

This process contributes to the carbon cycle in marine environments.

Question 5

Some organisms like plankton sequester CO2. What do they turn carbon into?

Answer 5

Organic matter

This process is essential for carbon storage in marine ecosystems.

Question 6

What do plankton use to produce their limestone protection?

Answer 6

Carbonate

This is part of their biological processes for protection.

Question 7

What happens to dead organisms in the ocean?

Answer 7

They sink to the bottom

This process contributes to carbon storage by sedimentation.

Question 8

What happens to the shells of organisms when they die?

Answer 8

Some shells dissolve into ocean water, becoming part of deep ocean currents

Dead organisms that sink to the seafloor become buried and compressed, eventually forming limestone sediments.

Question 9

What is formed when CO₂ from the atmosphere reacts with water in the oceans?

Answer 9

Carbonic acid

This process occurs on the surface of the oceans.

Question 10

As CO₂ concentrations in the atmosphere increase, what happens to the oceans?

Answer 10

Oceans absorb more CO₂, causing them to become more acidic

This acidification could have long-lasting negative effects.

Question 11

True or false: The movement of CO₂ is one way from the atmosphere to the ocean.

Answer 11

FALSE

Some CO₂ will go from the water back into the atmosphere.

Question 12

What is the Physical Pump in the context of ocean carbon storage?

Answer 12

Oceanic circulation provides a constant source of new water on the surface while transferring surface water into the deep ocean

This process enables the ocean to store a significant amount of carbon.

Question 13

How does the temperature of ocean water affect CO₂ absorption?

Answer 13

Colder water absorbs more CO₂

The concentration of CO₂ in the ocean varies around the world.

Question 14

Where is CO₂ concentration higher in the ocean?

Answer 14

10% higher in the deep ocean compared to the surface

Polar regions hold more carbon than tropical regions.

Question 15

What do warm tropical waters do with CO₂?

Answer 15

Release CO₂ to the atmosphere

Cold high latitude oceans absorb CO₂ from the atmosphere.

Question 16

What is thermohaline circulation?

Answer 16

An ocean current that produces both vertical and horizontal circulation of cold and warm water around the world’s oceans

It is influenced by atmospheric circulation, transferring water from warmer tropical areas to colder polar regions.

Question 17

How long does it take for a cubic metre of water to travel around the entire thermohaline circulation system?

Answer 17

Around 1000 years

This slow rate of circulation is crucial for the global climate and oceanic nutrient distribution.

Question 18

What happens to warm surface waters in the thermohaline circulation?

Answer 18

They are depleted of CO2 and nutrients

This depletion is essential for the foundation of the planet’s food chain, which relies on cool, nutrient-rich water.

Question 19

Why does cold water in the North Atlantic sink?

Answer 19

It is cold and very saline, making it denser and heavier

This sinking causes warm water to be drawn from the ocean surface.

Question 20

What is the first step in the thermohaline circulation process?

Answer 20

The main current begins in polar oceans where cold seawater sinks due to higher density

This initiates the circulation process.

Question 21

What recharges the current as it passes Antarctica?

Answer 21

Extra cold, salty, dense water

This recharging is vital for maintaining the strength of the thermohaline circulation.

Question 22

What are the two divisions of the main current in thermohaline circulation?

Answer 22

• Northward into the Indian Ocean
• Into the Western Pacific

These divisions help distribute water across different oceanic regions.

Question 23

What happens to the two branches of warm water as they travel northward?

Answer 23

• They warm and rise
• They loop back southward and westward

This describes the circulation pattern of ocean currents.

Question 24

What occurs to the warmed surface waters when they return to the North Atlantic?

Answer 24

They cool and the cycle begins again

This is part of the ocean circulation process.

Question 25

The rate of absorption of **CO₂** into the ocean depends on what factor?

Answer 25

Ocean temperatures ## Footnote Colder water absorbs more CO₂.

Question 26

True or false: As ocean temperatures increase, the oceans will absorb more **CO₂**.

Answer 26

FALSE ## Footnote Warmer oceans absorb less CO₂ and may emit stored carbon dioxide, accelerating climate change.

Question 27

What is the **positive feedback mechanism** related to ocean temperatures and CO₂ absorption?

Answer 27

As ocean temperatures increase, oceans absorb less CO₂ ## Footnote This can lead to further ocean warming.

Question 28

What is the essential role of the **oceans** in relation to climate?

Answer 28

Regulating climate and greenhouse gas emissions ## Footnote The oceans play a crucial role in maintaining Earth's climate balance.