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A Level Physical Geography > WCC: Carbon Cycle - The Carbon Budget and its Impact Upon Land, Ocean and Atmosphere > Flashcards

WCC: Carbon Cycle - The Carbon Budget and its Impact Upon Land, Ocean and Atmosphere Flashcards

The carbon budget. The impact of the carbon cycle upon land, ocean and atmosphere including global climate.

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1
Q

What is the carbon budget?

A

The amount of carbon that is stored and transferred within the carbon cycle

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2
Q

What is the most important role of the carbon cycle and why?

A

The greenhouse effect as it enables life to exist on Earth.

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3
Q

Briefly describe the changes in the carbon budget in the past 500 million years.

A

500 million years ago atmospheric CO2 was 20 times higher than present values.
It dropped, then rose again 200 million years ago to a maximum of 4 to 5 times present levels.
It then followed a slow decline until recent pre-industrial time.

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4
Q

Why are many of the impacts of the carbon cycle on land, atmosphere and oceans poorly understood?

A

Research so far has been over a relatively short time period, so results are unclear. There are also so many other variables that can cause change in the systems.

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5
Q

What are the 2 major parts of land that are impacted by changes in the carbon cycle?

A

Plants

Permafrost

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6
Q

What 2 ways can changes in the carbon cycle lead to more plant growth?

A

Carbon fertilisation

Increased growing season

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7
Q

What is carbon fertilisation?

A

Where more available CO2 results in more photosynthesis so more plant growth

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8
Q

How do changes in the carbon cycle increase growing season and how does this affect plant growth?

A

Increased temperatures increase the growing season.

This allows plants to grow at higher latitudes, increasing plant growth.

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9
Q

How can changes in the carbon cycle lead to less plant growth?

A

Changing weather patterns can increase the likelihood of droughts and wildfires in certain areas, so they can support less plant life.

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10
Q

Give an example of a place that can only just support plant life, making it vulnerable to increased likelihood of droughts due to changing weather patterns.

A

the Sahel

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11
Q

Why is the change in magnitude of plant life important?

A

It has a knock-on effect on the atmosphere as plants act as carbon sinks

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12
Q

In what 2 ways do changes in the carbon cycle affect permafrost and tundra?

A

Warming temperatures causes permafrost to melt and organic matter to decompose faster.

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13
Q

Give an example of how changes in the carbon cycle lead to positive feedback loops on land.

A

Warming global temperatures due to increased atmospheric CO2 lead to increased melting of permafrost and decomposition of organic matter. This would increase CO2 and methane emissions, warming global temperatures further.

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14
Q

How much carbon is estimated to be stored in permafrost in the Northern Hemisphere?

A

1672 GtC

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15
Q

Give evidence to show how changes to permafrost could affect global climate.

A

If just 10% of permafrost thawed it would release enough carbon to raise global temperatures by 0.7C by 2100.

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16
Q

What are the 5 major impacts changes in the carbon cycle have on the ocean?

A 
Oceanic acidification
Sea level rise
Melting sea ice
Ocean salinity
Ocean warming
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17
Q

What percentage of carbon released into the atmosphere diffuses into the ocean?

A

30%

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18
Q

How do changes in the carbon cycle cause ocean acidification?

A

Dissolving CO2 in the ocean creates carbonic acid, making the slightly alkaline ocean less alkaline.

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19
Q

Give evidence of ocean acidification.

A

Since 1750, the pH of the ocean’s surface has become 30% more acidic

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20
Q

What are the 2 main impacts of ocean acidification?

A

Negatively impacts marine ecosystems

Increases ocean carbon stores

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21
Q

How does ocean acidification affect marine ecosystems?

A

Carbonic acid reacts with carbonate ions in the ocean to form bicarbonate, however marine organisms need these carbonate ions to create their calcium carbonate shells. The reduction in available carbonate ions forces the organisms to expend more energy building their shells, which are thinner and more fragile as a result.

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22
Q

Give evidence to show the possible impacts of ocean acidification on polar and sub-polar marine ecosystems.

A

Polar and sub-polar marine ecosystems are projected to become so low in carbonate ions within this century that waters may become corrosive to unprotected shells and skeletons of organisms living there.

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23
Q

Which ecosystem is known to be significantly impacted by ocean acidification?

A

Coral reefs

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24
Q

Why are coral reefs vulnerable to ocean acidification?

A

Coral polyps need carbonate ions to create their shells

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25
Q

How can ocean acidification increase carbon stores?

A

More acidic seawater dissolves more calcium carbonate rocks. More carbonate ions will be released, increasing the ocean’s capacity to absorb CO2 over time.

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26
Q

What are the 3 main possible impacts of ocean warming?

A

Fewer phytoplankton
Bleaching of coral reefs
Increased growth of marine plants and phytoplankton

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27
Q

How do changes in the carbon cycle lead to ocean warming?

A

Increased atmospheric carbon enhances the greenhouse effect, leading to warmer oceans.

28
Q

Why does ocean warming lead to fewer phytoplankton?

A

Phytoplankton grow better in cool, nutrient-rich waters

29
Q

How could a reduction in phytoplankton impact the ocean?

A

It could limit the ocean’s ability to take carbon from the atmosphere through the biological carbon pump and lessen the effectiveness of the oceans as a carbon sink

30
Q

How can ocean warming lead to coral bleaching?

A

Warming kills of symbiotic algae which coral requires in order to grow

31
Q

How can ocean warming lead to increased marine plant and phytoplankton growth?

A

There are a few species such as sea grasses that take CO2 directly from the water. Increased oceanic CO2 could fertilise these species and increase their growth.

32
Q

Which 2 impacts of the carbon cycle on the oceans affects coral reefs?

A

Ocean acidification

Ocean warming

33
Q

Why are coral reefs so important worldwide?

A

They provide food and livelihood security for 500 million people

34
Q

What are the 2 major threats to coastal communities due to the loss of coral reefs?

A

Reduced food availability

Reduced capacity of coastlines to protect against sea level rise and increased storm surges

35
Q

Give data to show the scale of recent melting of sea ice

A

Arctic sea ice has retreated by 40% in the last 35 years

36
Q

Describe how changes in the carbon cycle causes the increased melting of sea ice.

A

Increased atmospheric carbon enhances the greenhouse effect, warming oceans. The subsequent melting means highly reflective ice is replaced by more heat absorbent water. This amplifies the warming, leading to more melting and creating a positive feedback loop.

37
Q

What are the 2 main impacts of melting sea ice on the oceans?

A

Loss of ice-bound algae

Loss of transport systems for polar organisms

38
Q

Where has there been an observed decrease in ocean salinity?

A

In the deep North Atlantic

39
Q

What is decreased ocean salinity caused by?

A

The increase in freshwater reaching oceans

40
Q

What are the 2 likely causes of more freshwater reaching the oceans?

A

Higher temperatures

Increased precipitation

41
Q

How do higher temperatures increase the amount of freshwater reaching oceans?

A

They cause the melting of the Greenland ice sheet and many alpine glaciers

42
Q

How does increased precipitation increase the amount of freshwater reaching oceans?

A

It leads to higher river runoffs that evetually flow to the sea

43
Q

What significant impact has decreased ocean salinity been linked to?

A

The slowing down of large-scale oceanic circulation in the northeast Atlantic Ocean

44
Q

How could the slowing down of oceanic circulation impact the climate?

A

If the North Atlantic drift current were disrupted, western Europe could experience significant cooling.

45
Q

Why could decreased ocean salinity be causing oceanic circulation to slow down?

A

Oceanic circulation is driven by the sinking of saline water in high latitudes. This would therefore decrease if there was less saline water.

46
Q

Give evidence to show how global sea levels are subject to change.

A

The last glacial retreat led to a worldwide rise in sea levels around 10,000 years ago.
Global sea levels have remained constant for the past 5,000 years, however have been rising since the 1990s.

47
Q

How fast have sea levels been rising since the 1990s?

A

3.5mm/year

48
Q

What are the 2 main causes for the most recent rise in sea level?

A

Increased melting of terrestrial ice

Thermal expansion

49
Q

How have changes in the carbon cycle caused thermal expansion?

A

Increased atmospheric carbon has enhanced the greenhouse effect, leading to warmer oceans. When water heats up, it expands.

50
Q

How much of the past century’s rise in sea level is thought to be attributable to thermal expansion?

A

About 1/2

51
Q

By how much are the oceans expected to rise by 2100?

A

Between 0.8 and 2m

52
Q

Give evidence to support the enhanced greenhouse effect

A

Average global temperatures have risen by about 0.8C since 1880

53
Q

Explain the greenhouse effect.

A

Solar radiation passes through the Earth’s atmosphere. Some solar radiation is reflected by the atmosphere and Earth’s surface. Most solar energy is absorbed by the Earth’s surface, warming it. As the surface gains heat it emits infrared radiation back into the atmosphere. Some infrared radiation passes through the atmosphere and is lost in space and some is absorbed and re-emitted by greenhouse gas molecules, warming the Earth’s surface.

54
Q

How much incoming solar energy is reflected back into space?

A

30%

55
Q

What allows infrared radiation to be trapped by greenhouse gas molecules?

A

It has a long wavelength

56
Q

What is the direct cause of the enhanced greenhouse effect?

A

Increased radiative forcing

57
Q

What is radiative forcing?

A

The difference between the incoming solar energy absorbed by the Earth and the energy radiated back into space.

58
Q

What is causing increased radiative forcing?

A

Increased greenhouse gases from anthropogenic sources

59
Q

What are the units for radiative forcing?

A

Watts/m^2 (of the Earth’s surface)

60
Q

When did radiative forcing start to increase?

A

1750

61
Q

What is the current level of radiative forcing according to the IPCC?

A

1.6 watts/m^2

62
Q

Give 3 ways changes in the carbon cycle can affect the atmosphere.

A

Enhanced greenhouse effect
Volcanic eruptions
Changes in phytoplankton populations

63
Q

What are the atmospheric effects of changes in phytoplankton populations?

A

More phytoplankton - more clouds and rain which can lead to more cooling
Less phytoplankton - less cloud formation and rain

64
Q

How do phytoplankton increase cloud formation?

A

Through the release of a chemical substance called dimethylsulphide, which forms cloud-condensation nuclei

65
Q

What is the atmospheric effect of a volcanic eruption?

A

A volcanic winter

66
Q

What is a volcanic winter?

A

Cooling of the climate caused by an extremely large volcanic eruption

67
Q

How do volcanic eruptions lead to volcanic winters?

A

Eruptions releases huge quantities of carbon dioxide, aerosols and particulate matter. These absorb incoming solar radiation preventing it from reaching the Earth’s surface leading to cooling on the Earth’s surface.

A Level Physical Geography (43 decks)

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