Changes in the Carbon Cycle

Question 1

What happened during the quaternary geological period?

Answer 1

Global climates fluctuated considerably between warm (interglacial) periodsand cold periods (glacial)

Question 2

Higher temperatures are associated with…

Answer 2

Higher carbon dioxide levels in the air

Question 3

An increase in the level of carbon dioxide in the air leads to..

Answer 3

Enhanced global warming and subsequent temperature increase

Question 4

Lower levels of carbon dioxide…

Answer 4

Reduces the effectiveness of the greenhouse effect

Question 5

What is the impact of cold conditions on carbon stores and transfers?

Answer 5

• chemical WEATHERING processes would have been more ACTIVE as cold water can hold more CO2
• DECOMPOSERS would have been LESS active, so carbon transfer to soils would be reduced
• SOIL would be FROZEN OVER vast areas of land. This would have stopped transfers of carbon
• less water would FLOW into oceans because it would be LOCKED UP on the land, therefore less BUILDUP of SEDIMENTS on the ocean floor
• FOREST COVERAGE would be different (geographically and its total area). This would affect the distribution of processes such as photosynthesis and respiration

Question 6

What are the impacts of warmer temperatures on carbon stores and transfers?

Answer 6

Carbon stored in permafrost (along with other gases eg methane) are now being released into the atmosphere when it melts which further enhances the greenhouse effect, leading to increased warming.

This positive feedback system leads to a further destabilisation of the system.

Question 7

Where is the melting of permafrost prevalent?

Answer 7

In tundra regions such as Russia and Siberia

Question 8

How do wildfires affect the carbon cycle?

Answer 8

Even though forests only cover a small surface of the Earth, wildfires (started by lightening, or deliberately by people) turn forests from being a carbon sink into a carbon source because combustion returns huge quantities of carbon back into the atmosphere.

Question 9

Example of a wildfire?

Answer 9

In 2013, the Indonesian wildfires burned out of control for months and their smoke spread to South-East Asia.

Question 10

How does volcanic activity affect the carbon cycle?

Answer 10

Eruptions return to the atmosphere that has been trapped for millions of years in rocks stored deep within the Earth’s crust.

Question 11

When were volcanoes most active?

Answer 11

In the polaeozoic period

Question 12

How much carbon dioxide do volcanoes emit in comparison to human activity per year?

Answer 12

Volcanoes = between 130 and 380million tonnes of CO2

Humans = 30 billion tonnes of CO2

Question 13

How does lava affect the carbon cycle?

Answer 13

Lava contains silicates which slowly weather. This converts CO2 in the air into carbonates in solution. In this way, carbon is absorbed very slowly from the atmosphere.

Question 14

What do scientists believe the trigger is for the delay between temperature and carbon dioxide levels in the Vostock ice core?

Answer 14

Orbital change - the Milancovitch cycles.

These regular cycles of orbital eccentricity cause slight variations in the amount of suns radiation that warms up the Earth.

So, as temperatures start to rise at the end of a glacial period (triggered by orbital change), there is a surge of carbon dioxide released into the atmosphere by the warming of the oceans and unlocking of land surface that had previously been frozen.

This surge of CO2 enhances the greenhouse effect, amplifying the warming trend.

Question 15

Interglacial periods?

Answer 15

Warm periods

Question 16

Glacial periods?

Answer 16

Cold periods

Question 17

What is the IPCC?

Answer 17

Intergovernmental Panel on Climate Change

Question 18

What does anthropogenic mean?

Answer 18

Human caused

Question 19

According to the IPCC, what % of anthropogenic carbon release comes from the combustion of fossil fuels?

Answer 19

90%

Question 20

Since the 1960s, global concentrations of carbon dioxide have increased dramatically from … ppm to … ppm

Answer 20

From 320 ppm to 400 ppm

Question 21

What are fossil fuels?

Answer 21

Natural sources of energy formed from the remains of living organisms, primarily plants. They are extremely important long term stores of carbon, comprising carbon locked away within the remains of organic matter.

Question 22

Today, where is most of the world’s oil and gas extracted from?

Answer 22

Rocks that are 70 - 100 million years old

Question 23

What happens when fossil fuels are burnt to generate electricity and power?

Answer 23

The stored carbon is released, primarily as carbon dioxide into the atmosphere, accelerating the cycle of this carbon.

Once in the atmosphere, it enhances the natural greenhouse effect, increasing global temperatures - “global warming”.

Question 24

Since the late 1950s, how has carbon dioxide in the atmosphere has been measured?

Answer 24

By the Hawaiian Volcanic Observatory

Question 25

How much is land use responsible for global carbon release?

Answer 25

10%.

Question 26

How do livestock increase methane production?

Answer 26

Livestock (especially cattle), RUMINATE, which produces methane as a byproduct.

Question 27

Why is there a desirability or move away from such high dependence on meat and dairy products?

Answer 27

Because cattle alone release 20% of total methane emission sin the USA.

Question 28

What is the link between methane and rice?

Answer 28

Methane is produced from the cultivation of rice - up to 20% of global methane production.

Question 29

What has research in Asia and North America found regarding rice yields?

Answer 29

Rice yields have increased by 25% due to increased levels of carbon dioxide levels in the air. (But in turn has lead to a 40% increase in methane emissions).

Question 30

Why will the methane emissions from rice continue?

Answer 30

Because rice is the primary food source for 50% of the world’s population.

Question 31

Define deforestation.

Answer 31

The removal of trees, either by burning or felling, for building, ranching, mining or the growth of commercial crops such as palm oil or soya.

Question 32

Where is deforestation most common?

Answer 32

It is widespread across the world, but is particularly concentrated in tropical regions.

Question 33

How does deforestation affect the carbon cycle?

Answer 33

In a natural system, when a tree dies it decomposes very slowly and releases carbon over along period of time. During that time, new vegetation begins to grow and quickly compensates for the carbon released by the dead tree - so the system is carbon neutral.

However, when deforestation by burning occurs, carbon is immediately released into the atmosphere (and if the land is used for a different purpose, e.g. grassland for cattle ranching, then the future absorption of CO2 will be reduced.

(Now a source - not a sink).

Question 34

Globally, how much of the Earth’s surface is covered by urban areas?

Answer 34

2%

Question 35

Urban areas account for how much of global anthropogenic carbon emissions?

Answer 35

97%

Question 36

How does cement affect carbon cycles?

Answer 36

Carbon dioxide is a byproduct

Question 37

Why do volcanoes only have a small scale impact on climate?

Answer 37

Because when they erupt, they release carbon dioxide into the atmosphere along with ash and other gases. This absorbs more incoming radiation from the sun and can lead to a volcanic winter - a reduction in global temperatures.

Question 38

Why may increased ocean temperatures cause more clouds to form?

Answer 38

Because these warmer temperatures along with more sunshine attracts marine phytoplankton (which release DMS) which promote condensation - and therefore cloud formation - over the ocean.

Question 39

What is ocean acidification?

Answer 39

The ongoing decrease in ocean pH caused by human CO2 emissions (e.g. the burning of fossil fuels).

Question 40

Explain the effect of ocean acidification for coral reefs.

Answer 40

Ocean acidification may decrease the reef growth by reducing calification rates, and this affects the skeletal growth of reef building organisms.

Question 41

Explain how in the past decade the global carbon cycle has been negatively affected.

Answer 41

• wildfires burn large areas of peatland which release the previously stored carbon dioxide into the atmosphere. This release of CO2 leads to global warming.
• also when dry peat burns down to the water table, tree roots are exposed meaning the forest vegetation becomes unstable, and trees fall with large areas of forest being lost.
• thirdly, the smoke from the fire reduces light intensity that reaches pleats near the areas of the forest fires, as sunlight is blocked out. This therefore reduces photosynthesis and subsequently less CO2 is converted into O - so there is more carbon in the atmosphere.

Question 42

What is a net carbon sink?

Answer 42

When more carbon enters a store than leaves it

Question 43

What is a net carbon source?

Answer 43

When more carbon leaves a store than enters it.

Question 44

What is the geological component of the carbon cycle?

Answer 44

Where it interacts with the rock cycle in the processes of weathering, burial, subduction and volcanic eruptions.

Question 45

How is carbon dioxide removed from the atmosphere?

Answer 45

By dissolving it in water and forming carbonic acid

Question 46

Carbon dioxide dissolves in water to form carbonic acid. What happens when this acidic water reaches the surface of the Earth as rain?

Answer 46

When it reaches the surface, it reacts with minerals at the Earth’s surface - slowly dissolving them into their component ions through chemical weathering. These component ions are carried in surface waters (eg streams and rivers) where they settle our as minerals like calcite - a form of calcium carbonate.