The Carbon Cycle - Global scale

Question 1

What is a carbon sink?

Answer 1

Any store that takes in more carbon than it emits. E.g. Tropical rainforest.

Question 2

What is a carbon source?

Answer 2

Any store that emits more carbon than it stores. E.g. Damaged tropical rainforest

Question 3

Where did our carbon emissions come from (1750-2012)?

Answer 3

Coal - 673 Gt
Land use - 590 Gt
Oil - 496 Gt
Gas - 202 Gt
Cement - 36 Gt

Question 4

Where did our carbon emission get stored (1750-2012)?

Answer 4

Atmosphere - 879 Gt
Ocean - 590 Gt
Land - 528 Gt

Question 5

What are the main carbon stores? (6)

Answer 5

In order of magnitude:
Marine sediments&sedimentary rocks, oceans, fossil fuel deposits, soil organic matter, atmosphere, terrestrial plants

Question 6

How do marine sediments & sedimentary rocks store carbon?

Answer 6

Lithosphere - long term.
Biggest store of carbon. The rock cycle and continental drift recycle rock over time, but this may take thousands, if not millions of years

Question 7

How do the oceans store carbon?

Answer 7

Hydrosphere - Dynamic.
Second biggest store but only a small percentage compared to the largest store.
Carbon is constantly utilised by marine organisms, lost as an output to the lithosphere, or gains as an input to rivers and erosion

Question 8

How to fossil fuel deposits store carbon?

Answer 8

Lithosphere - Long term but currently dynamic.
humans exploit these rapidly, thought 4000 billion metric tons remain as fossil fuels

Question 9

How does soil organic matter store carbon?

Answer 9

Lithosphere - mid term.
Soil can store carbon for over a thousand years. Deforestation, agriculture, and land use change are affecting this store.

Question 10

How does the atmosphere store carbon?

Answer 10

Atmosphere - Dynamic.
Human activities caused CO2 in atmosphere to increase by around 40% since the industrial revolution.

Question 11

How do terrestrial plants store carbon?

Answer 11

Biosphere - mid term but very dynamic.
Vulnerable to climate change and deforestation - carbon storage annually declining.

Question 12

How is carbon storage in the lithosphere distributed?

Answer 12

The lithosphere is the main source of carbon but unevenly distributed.
E.g. oceans in southern hemisphere are larger than northern hemisphere and most biosphere occurs on land.
Terrestrial plant storage is focussed in the tropics and northern hemisphere

Question 13

What changes has there been to non-tropical forests according to climate change information?

Answer 13

Increase in carbon sequestration in recent (especially Europe & Asia), due to conversion of agricultural land and plantations to new forests

Question 14

What changes has there been to forests in industrialised regions according to climate change information?

Answer 14

Expected to increase by 2050.
But in global south, forested areas will decrease

Question 15

What changes has there been to the rate of forest loss according to climate change information?

Answer 15

Decreased from 9.5 million hectares per year to 5.5 million hectares per year in 2010-2015

Question 16

What are the 8 countries with the largest forested areas?

Answer 16

Russia, brazil, china, canada, USA, DRC, Australia and Indonesia

Question 17

Why is brazil relevant to climate change?

Answer 17

Has the most carbon stored (rainforest) on land and the most extensive deforested area

Question 18

Why is china relevant to climate change?

Answer 18

Has the largest amounts of afforested areas

Question 19

What is Net Primary Productivity (NPP)?

Answer 19

Amount of carbon absorbed by forests. For tropical rainforests, this is positive all year round. But deciduous forests have a negative in winter, but a positive for the whole year

Question 20

What are natural processes that alter the carbon cycle? (2)

Answer 20

Wildfires, Volcanic activity

Question 21

How do wildfires alter the carbon cycle?

Answer 21

Biosphere - Atmosphere. CO2 released by burning.
Burning can encourage future plant growth.
Global warming allows more conditions for wildfires

Question 22

How does volcanic activity impact the carbon cycle?

Answer 22

Mainly CO2 gas. Contribute a relatively low proportion of CO2 to the overall carbon cycle. Sometimes also produce SO2, which can reduce radiation from entering (cooling temperatures temporarily).
May reduce photosynthesis - which then impacts the water cycle

Question 23

What are the human impacts which alter the carbon cycle? (3)

Answer 23

Fossil fuel use, Deforestation (+land use change), farming practices

Question 24

How does fossil fuel use impact the carbon cycle?

Answer 24

Combustion - Lithosphere-Atmosphere. Long term carbon sink

Question 25

How do farming practices impact the carbon cycle?

Answer 25

Pastoral farming releases CO2 as animals respire. Ploughing can release CO2 in soils. Farming machinery can produce CO2

Question 26

What are fluxes?

Answer 26

Changes to the magnitude of carbon stores. May happen rapidly or over thousands of years.
Human impacts are causing unprecedented flux in CO2 from fossil fuel combustion

Question 27

What is the carbon budget?

Answer 27

The balance between carbon inputs and outputs to a store at any scale or the balance of exchanges between the four major stores

Question 28

What is a carbon source?

Answer 28

A store that emits more carbon than it absorbs

Question 29

What is a carbon sink?

Answer 29

A store that absorbs more carbon than it emits