Global Climate: 2.1 Causes of Climate Change

Question 1

Explain the greenhouse effect

Answer 1

• Short-wave radiation from the sun filters through the atmosphere, allowing visible light through.
• This is absorbed by the earth’s surface.
• Long-wave radiation is emitted back towards the atmosphere.
• This is absorbed by greenhouse gases.
• Long-wave radiation is re-emitted back to earth as heat, warming the earth.

Question 2

Define the word System

Answer 2

A system is a set of interrelated parts and the connections between them. These parts unite to form a complex whole and produce emergent properties.

Question 3

Define the 3 parts of a system with examples.

Answer 3

Inputs: the elements that go into a system in order for there to be processes, outputs and feedback. E.G. material; water entering the atmosphere or energy; solar radiation.
Processes: act on the inputs and transform them into outputs (e.g. water in the atmosphere becomes rain and returns to the Earth’s surface).
Outputs/feedback: the flows of matter and/or energy that leave a system (e.g. the atmosphere radiates heat into space).

Question 4

Define open and closed systems.

Answer 4

An open system exchanges matter and energy with its surroundings.
A closed system exchanges energy but not matter with its surroundings.

Question 5

Define positive and negative feedback loops.

Answer 5

A system output re-enters the system as feedback and becomes a new input.
Response to change = the feedback moves the system in the same direction (positive feedback) or the opposite direction (negative feedback).

Question 6

Describe this negative feedback loop: clouds

Answer 6

1. Global temp. rises.
2. More evaporation of water.
3. Water vapour forms clouds in atmosphere.
4. Albedo increases, reflects more incoming short-wave radiation.
5. Global temp. falls. Less evaporation. Less clouds. More incoming radiation.
6. Global temp. rises again.

Question 7

Describe this positive feedback loop: ice caps melting

Answer 7

1. Global temp. rises.
2. Ice caps melt.
3. Soil is exposed, lower albedo, more absorption of heat.
4. Global temp. rises more.

Question 8

4 Benefits of the atmosphere.

Answer 8

1. A shield from meteorites
2. Protects us from sun’s harmful radiation
3. Moderates and stabilises our climate, including temperature
4. Supplies O2 and CO2 for producers and consumers.

Question 9

Structure of the atmosphere + Pressure and Temperature through the atmosphere.

Answer 9

VERTICALLY LAYERED STRUCTURE:
Pressure decreases steadily with height.
Temperature does not change uniformly with altitude.

Question 10

4 layers of the atmosphere (closest to farthest)

Answer 10

Troposphere - below 10km (0-10km)
Stratosphere - below 50km (10-50km)
Mesosphere - below 80km (50-80km)
Thermosphere - above 80km (80km-1000km)

Question 11

What happens in the troposphere. (5)

Answer 11

• The Earth’s surface absorbs heat from the sun then heats atmosphere through conduction.
• Winds increase with height.
• Most of the atmospheric mass is found in this layer. (Water vapour, clouds, pollutants).
• Most of our weather occurs here.
• Most organism interaction through the exchange of gases or through the introduction of pollutants.
• The greenhouse effect occurs here.

Question 12

What happens in the stratosphere. (5)

Answer 12

• Absorbs UV radiation from the sun.
• Winds increase with height.
• Temperature is about –60°C in the lower part of the stratosphere, shielded by the ozone layer.
• Temp. increases with height.
• The air is dry.

Question 13

What happens in the mesosphere. (2)

Answer 13

1. No ozone or other particulates to absorb UV heat, so temp. declines with height (reaching as low as –90°C).
2. Strong winds up to around 3000 km/h.

Question 14

What happens in the thermosphere (2) and inosphere (3).

Answer 14

• Absorbs UV + X-radiation from sun, breaking molecules into atoms (mainly oxygen, nitrogen and helium in the upper thermosphere).
• Temp. increases with height (can reach beyond 2000°C). Heat can cause thermosphere to expand, causing a variation in depth over time (500 to 1000 km).
• Ionosphere is located within the thermosphere + is an area with electrically charged particles.
• Short-wave radiowaves bounce off these ions back to Earth = allows communication over large distances.
• Northern/southern lights occur as electrically charged particles from the sun collide with ions in the ionosphere.

Question 15

How incoming solar radiation is lost. (with rough figures)

Answer 15

100 units of incoming solar radiation:

• 19 absorbed by atmosphere and clouds
• 51 absorbed by earth’s surface
• 30 reflected and scattered by albedo (surface, clouds)

Question 16

Albedo definition and examples.

Answer 16

The proportion of short-wave solar radiation that is reflected by a surface. 
Planetary albedo is 30%.
Asphalt and forest: 10%
Soil and grass: 20%
Desert sand 40%.
Concrete: 50%
Clouds 40–90%.
Fresh snow 80–90%.

Question 17

4 greenhouse gases, their natural sources and sinks.

Answer 17

Water vapour. varies ppm
Sources: water bodies, respiration, volcanic eruptions.
Sinks: water boides, living organisms.

Carbon dioxide. 300ppm
Sources: respiration, volanic activity.
Sinks: vegetation, fossil fuels.

Methane. 700ppn
Sources: livestock, anaerobic decomposition.
Sinks: soil, chemical reactions in troposphere.

Nitrous oxide: 250ppb
Sources: nitrogen cycle nitrification, denitrification.
Sinks: stratosphere.

Question 18

What effects the amount of energy that the earth receives from the sun? (4)

Answer 18

• Energy output from the sun
• The latitude of a location
• Time of day and time of year
• Variations in the composition of the atmosphere.

Question 19

Describe the role of rotation and revolution briefly.

Answer 19

The Earth rotates on its own axis and it revolves around the sun. This mpacts energy received from sun.

1. Rotation creates day and night.
2. Revolution on the Earth’s tilted axis creates the seasons.
3. The combo of rotation&revolution causes varying day length throughout the year.

Question 20

Explain how rotation impacts solar radiation.

Answer 20

1. The Earth rotates on its axis once every 24 hours, creating day and night.
2. Due to the tilt of the Earth’s axis, day length varies. 3. At the equator days and night are about 12 hours all year round.
3. At the poles daylight can be 24 hours in summer and 0 hours in winter.
4. This affects the amount of solar radiation received by the poles.
5. The longer the day, the greater the solar energy input.

Question 21

Explain how revolution impacts solar radiation.

Answer 21

1. The Earth takes 365 days to revolve around the sun.
2. The Earth revolves around the sun on an elliptical orbit, causing seasons.
3. The tilt of the Earth’s axis results in rays of the sun hitting the surface at different angles.
4. When tilted towards the sun, the angle of incidence of solar radiation is higher and there will be summer.
5. When tilted away from the sun, the solar energy is spread over a wider area and temperatures are lower.

Question 22

Explain how latitude impacts solar radiation.

Answer 22

1. The sun is always overhead between 23°N north and 23°S south tropics of the equator = most intense heat. 2. At higher latitudes, the angle at which the sun’s rays hit the Earth (incidence) = more slanted, and the heating less intense.
2. The lower the angle of incidence the greater the area over which the heating is spread = less warmth for the Earth’s surface.
3. At higher latitudes, solar energy must pass through more atmosphere to get to the Earth’s surface = looses heat.

Question 23

What is global dimming + causes.

Answer 23

The reduction of solar radiation reaching the earth, lowering the temperature. Happened in 1950’s-90s.
Caused by: particulates (ash, soot) and sulfate aerosols from natural/anthropogenic activity. (volcanoes, fossil fuels).
- Reflect more sunlight back to space.
- Affect characteristics of clouds: acting as seeds for water, increasing albedo.

Question 24

Outline volcanic eruptions impact on solar radition.

Explain the Laki fissure system and Mount Pinatubo.

Answer 24

Eruptions produce CO2, ash particles and sulfur-rich gases.
The Laki fissure system in Iceland erupted for 8 months in 1783, producing:
- a dense cloud of ash that spread into the stratosphere
- a haze across Europe
- toxic gases; sulfur dioxide, hydrogen chloride and hydrogen fluoride gases produced acid rain, killed crops and livestock
- record low temperatures were recorded in the USA in 1783/84
- northern hemisphere temp. dropped 1°C.

1991 Mount Pinatubo in the Philippines ejected 17 million tons of ejecta into the atmosphere. Ash, lava, dust and aerosols reached the stratosphere. The results were:

• 10% drop in the amount of sunlight reaching the Earth’s surface
• a drop in northern hemisphere temperatures of 0.5°C
• a cloud in the stratosphere that lasted for 3 years
• a large amount of ozone was destroyed.

Question 25

Explain how volcanoes can cause positive feedback cycles which may cause mini ice ages.

Answer 25

1. Major eruptions inject ash and particulates into the stratosphere.
2. Reflect incoming solar radiation.
3. Sea ice expands down the coast of Greenland.
4. Sea ice melts as it reaches the North Atlantic.
5. Sea ice does not mix with ocean water.
6. The great ocean conveyor belt is inhibited and heat is not transferred to arctic area from tropics.
7. Sea ice expands more.

Question 26

Explain a Positive Feedback Cycle of Decreased Albedo

Answer 26

1. Darker surface.
2. Less reflection of solar radiation, more absorption.
3. More heat, temp. rises.
4. Ice melts, revealing more soil.
5. More absorption, temp. rises more.

Question 27

Why is methane bad + What are the main causes of increased methane in the atmosphere?

Answer 27

Methane = 85x more powerful than carbon dioxide PPB.
Increased by: burning fossil fuels, increased animal agriculture and rice paddies, melting permafrost, increasing population.

Question 28

Impacts on the amount of water vapour in the atmosphere. (5)

Answer 28

1. A byproduct of the combustion of fossil fuels is water vapour. The exhaust fumes from petrol engines are 13% water vapour.
2. Electricity, geothermal and nuclear power generation produces a lot of steam as a byproduct.
3. Agricultural production: irrigation.
4. Deforestation is believed to have cut evaporation rates by 5%, offsetting the increase in evaporation caused by irrigation.
5. Positive feedback loops will intensify the changes and will continue to add to the problem.

Question 29

Human causes of changes to atmospheric Carbon Dioxide. (3)

Answer 29

1. Combustion of fossil fuels (coal then oil then gas) releases energy that humans use for power and heat generation, transportation (oil, oil derivatives) and industrial processes (drive machinery,produce heat and steam for production).
2. Deforestation: Plants act as carbon sinks and removing natural vegetation decreases CO2 being taken out of the atmosphere.
3. Cement production release large amounts of carbon dioxide as part of the manufacturing process. The petrochemical industry is another significant source of carbon dioxide.

Question 30

Causes of changes to Nitrous Oxide

Answer 30

1. Agriculture: released during microbial processes that break down nitrogen in fertilisers, manure and urine. Released as a byproduct during the manufacture of nitric acid used to make fertilisers.
2. Nitrous oxide is emitted when fossil fuels are burned.
3. Transportation, thermal power stations, industrial processes, burning biomass,
4. Atmospheric deposition in rainfall washes these compounds back to Earth. This adds nitrogen to the soil system, which stimulates microbial activity, thus releasing nitrous oxide.
5. The bacteria that live in sewage treatment facilities produce nitrous oxide. Human sewage is broken down by nitrification and denitrification of the nitrogen compounds in urine and faeces.

Question 31

What is the tropospheric ozone? How does it form?

Answer 31

1. Combustion of fossil fuels increases Carbon and Nitrogen in the atmosphere.
2. With sunlight, photochemical reaction takes place.
3. Forms smog and is a major pollutant.
4. Lowering air quality indicates higher tropospheric ozone levels.

Question 32

What are chlorofluorocarbons + changes in the atmosphere?

Answer 32

CFCs are artificial substances with no natural source and all of them are strong GHGs. They are used as refrigerants and industrial solvents. HCFCs and HFCs are increasing whereas CFCs are levelling off or decreasing.

1928 - ammonia, methyl chloride and sulfur dioxide were used as refrigerants.
1928 - CFCs were synthesised in the laboratory.
1950s/60s - used in domestic appliances, hence the rise in the amount of CFCs in atmosphere.
1989 - Montreal Protocol to phase out ozone-depleting substances, successful in reducing CFCs but CFCs are a long-lived GHG that remain in the atmosphere for over 100 years, so their warming effect will continue.

Question 33

GHG Emissions by China, the USA and Europe

Answer 33

China: 25% total emissions, 20% energy
United States: 15% total emissions, 15% energy
Europe: 10% total emissions, 10% energy

Question 34

How the Industrial Revolution impacted GHG emissions. (4)

Answer 34

• Mechanisation of agriculture requires fossil fuels:
  to run machinery
  to produce chemicals e.g. fertilisers, pesticides, etc.
  to run the supply chain: bringing raw materials of farming and distributing the produce.
• Construction of the urban area buildings, cement and transport links, public transport or private.
• Electricity increases significantly to meet rising demand.
• Land use changes: vegetation cleared for urban and industrial expansion, addition of power stations and waste disposal facilities, etc.

Question 35

Why HIC’s have lower GHG emissions.

Answer 35

• Moved away from manufacturing industries to tertiary and quaternary industries.
• Companies based in the developed countries are transnational corporations. For example, Nike is based in Oregon, USA, but its factories are located in China (124), Thailand (73), South Korea (35) and Vietnam (34).
• Better technology is now available to reduce GHG emissions: Catalytic convertors on most cars, Electricity moving from thermal to renewable.
• Vehicles now run on alternatives to fossil fuels (e.g. ethanol).
• Green movement is becoming stronger in many developed countries: environmental laws+legislation clean up emissions at source before releasing into atmosphere.
• Deforestation is being restricted and reforestation is increasing. Removes CO2.
• HICs part of Kyoto Protocol, targets reduction of GHGs.

Question 36

Globalisation and GHG Emissions

Answer 36

• The increase of international interaction of nations, governments, companies and people.
• Driven by international trade, IT, transportation and freer movement of capital, good and services
• Positive impacts: job creation, foreign direct investment in LIC’s, sharing of ideas and cultures and awareness of global issues.
• Negative impacts: increase in inequalities between countries’ wealth, domination by TNCs, protectionist polices and loss of cultural identity.
  Globalisation increases international trade, which is reliant on transport, increasing GHG emissions.
  OR International trade facilitates globalisation as it moves goods around the world.