Carbon

Question 1

What created Earth’s early atmosphere (4000 MYA)?

Answer 1

Volcanic outgassing

Question 2

Which gases dominated Earth’s early atmosphere?

Answer 2

Carbon dioxide, nitrogen, and water vapour

Question 3

What key gas was largely absent from the early atmosphere?

Answer 3

Oxygen

Question 4

When did oxygen begin accumulating in oceans and the atmosphere?

Answer 4

Around 2 billion years ago

Question 5

Around when did primitive bacteria first evolve?

Answer 5

About 3 billion years ago

Question 6

What process did early bacteria carry out that changed the atmosphere?

Answer 6

Photosynthesis

Question 7

What gas did early photosynthetic bacteria release?

Answer 7

Oxygen

Question 8

Where did increasing amounts of carbon become stored around 2 billion years ago?

Answer 8

Oceans and sediments

Question 9

When did complex land organisms begin to develop?

Answer 9

Around 400 million years ago

Question 10

Which rock type stores the largest proportion of carbon?

Answer 10

Limestone (≈42%)

Question 11

What percentage of carbon is stored in sandstone?

Answer 11

About 25%

Question 12

What percentage of carbon is stored in shale?

Answer 12

About 33%

Question 13

When did the Carboniferous period occur?

Answer 13

Around 290 million years ago

Question 14

What major carbon store formed during the Carboniferous period?

Answer 14

Coal and other fossil fuels

Question 15

What happened to the carbon cycle before the industrial era?

Answer 15

It was roughly balanced (natural sources ≈ natural sinks)

Question 16

What is the largest long‑term carbon store on Earth?

Answer 16

Sedimentary rocks

Question 17

How is carbon stored in sedimentary rocks?

Answer 17

As carbonates (e.g., limestone)

Question 18

Why is carbon release from sedimentary rocks very slow?

Answer 18

It occurs through weathering and tectonic activity

Question 19

What is the main long‑term carbon store in the ocean?

Answer 19

Dissolved inorganic carbon in the deep ocean

Question 20

What characterises long‑term carbon stores?

Answer 20

Very slow cycling (hundreds to millions of years)

Question 21

What is stored in terrestrial soil?

Answer 21

Carbon from dead plant material and biomass

Question 22

What breaks down carbon in soils?

Answer 22

Microorganisms

Question 23

In which climate does soil carbon decompose fastest?

Answer 23

Hot, humid climates

Question 24

What does the surface ocean do with atmospheric CO2?

Answer 24

Exchanges and absorbs it

Question 25

How does the surface ocean absorb carbon biologically?

Answer 25

Through plankton photosynthesis

Question 26

What happens to some carbon absorbed by the surface ocean?

Answer 26

It sinks to the deep ocean

Question 27

What gases does the atmosphere store as part of the carbon cycle?

Answer 27

CO2 (carbon dioxide) and CH4 (methane)

Question 28

What is the residence time of atmospheric carbon?

Answer 28

Up to ~100 years

Question 29

How do terrestrial ecosystems store carbon?

Answer 29

In plants through photosynthesis

Question 30

How quickly can carbon cycle through plants?

Answer 30

Seconds to minutes

Question 31

What human activities disrupted the carbon balance?

Answer 31

Burning fossil fuels and deforestation