Human impacts: atmosphere

Question 1

Greenhouse gases

Answer 1

Carbon dioxide,

methane,

water vapour,

nitrous oxides

Question 2

Role of trees in the carbon cycle

Answer 2

Act as carbon sinks,

sequestering carbon dioxide from the atmosphere by photosynthesis

Question 3

The main source of CO₂ emissions

Answer 3

Burning fossil fuels

Question 4

Describe the greenhouse effect

Answer 4

• Light energy from the sun reaches the earth and is re-radiated as heat.
• Greenhouse gases in the atmosphere trap the heat, preventing it from escaping into space.
• This regulates the earth’s temperature, preventing it from becoming too cold at night.

Question 5

Explain the enhanced greenhouse effect

Answer 5

• Deforestation means less CO₂ is sequestered.
• Industrialization means more CO₂ is released.
• CO₂ levels in the atmosphere are increasing.
• This leads to global warming

Question 6

Sum total of all of an individual’s CO₂ emissions

Answer 6

Carbon footprint

Question 7

Ways to personally reduce CO₂ emissions/carbon footprint

Answer 7

• Decrease fuel consumption by walking, cycling, using public transport or using a car-pool.
• Minimise air travel.
• Use less electricity.
• Insulate your home.
• Use alternative energy.
• Buy locally made goods.
• Eat less meat and processed foods.

Question 8

Main sources of methane emissions

Answer 8

• Decomposition in landfills
• Sewage plants
• Natural gas and crude oil industries
• Rice plantations
• Faeces of livestock

Question 9

Productive land is transformed into a desert

Answer 9

Desertification

Question 10

Causes of desertification

Answer 10

• Climate change leads to less rain and warmer weather
• Poor land management

Question 11

Examples of poor farming practices that lead to desertification.

Answer 11

• Overgrazing or under grazing
• over-cultivation
• irrigation using poor quality groundwater
• deforestation

Question 12

Effects of desertification

Answer 12

• Loss of vegetation
• Soil erosion
• Loss of biodiversity
• Soil releases more CO₂
• The decline in soil quality
• Social unrest

Question 13

Ways to combat desertification

Answer 13

• Prevent climate change
• Improved farming techniques
• Reduce deforestation

Question 14

Effects of global warming

Answer 14

• Desertification
• Increase in droughts and floods
• Increase in extreme weather events
• Melting polar ice caps and glaciers
• A rise in sea surface temperatures
• Loss of biodiversity
• Spread of disease
• Social unrest

Question 15

Deforestation

Answer 15

Permanent destruction of indigenous forest by felling and burning in order to clear land for other purposes

Question 16

Reasons for deforestation

Answer 16

• Clearing land for urban development or agriculture
• Use of wood for fuel or as a building material
• Mining
• Harvesting for traditional medicines

Question 17

Effects of deforestation

Answer 17

• Increased global warming due to reduced carbon sequestration
• Soil erosion
• Reduced soil quality
• Flooding
• Loss of biodiversity
• Disruptions to the water cycle

Question 18

Role of trees in the water cycle

Answer 18

• Return water vapour to the air by transpiration - leads to cloud formation
• Slow run-off and allow water to sink into the soil

Question 19

Ways to reduce deforestation

Answer 19

• Recycle paper and cardboard
• Legislation to protect forests
• Plant trees
• Select specific trees instead of clear-cutting
• Create awareness
• Promote sustainable practices
• Mosaic forestry

Question 20

Mosaic forestry

Answer 20

Keeping areas of indigenous plants between trees planted for logging.

Question 21

Ozone

Answer 21

• O₃ gas in the atmosphere
• Highly reactive
• Absorbs UV radiation, preventing it from reaching the lower atmosphere.

Question 22

The main cause of global warming

Answer 22

Enhanced greenhouse effect caused by the build-up of greenhouse gases in the earth’s atmosphere. (NOT the hole in the ozone layer!).

Question 23

Ozone-depleting substances

Answer 23

• Gases containing chlorine or bromine.
• When released into the stratosphere they break down releasing Cl or Br, which cause degradation of ozone.
• e.g. CFCs

Question 24

Responsible for higher levels of UV radiation, especially over the South Pole

Answer 24

Ozone depletion

Question 25

Ways to combat ozone depletion

Answer 25

• Regulation and banning of ODS use
• Alternatives to ODSs in industry
• Create awareness
• Use “ozone friendly” products