Ch 7.3 What are the causes of global warming?

Question 1

What are the types of greenhouse gases?

Answer 1

1. Carbon dioxide.
2. Methane.
3. Nitrous oxide.
4. Ozone.
5. Water vapour.

Question 2

What are the natural sources of carbon dioxide?

Answer 2

1. Respiration of living organisms.
2. Decay of organic matter.
3. Wildfires.
4. Volcanic eruptions.

Question 3

What are the natural sources of methane?

Answer 3

1. Decomposition of organic matter in an environment with insufficient oxygen, such as in wetlands, oceans, rivers.
2. Melting of permafrost (Cold conditions prevent organic materials in the permafrost from decomposing. As the climate warms, the organic materials will decompose, releasing carbon into the atmosphere as methane and carbon dioxide.

Question 4

What are the natural sources of nitrous oxide?

Answer 4

Break down of nitrogen-containing compounds by bacteria in soils and oceans.

Question 5

What are the natural sources of ozone?

Answer 5

Chemical reaction involving hydrocarbons and nitrous oxides, as well as ozones itself with sun.

Question 6

What are the natural sources of water vapour?

Answer 6

Evaporation from the earth’s surface.

Question 7

What are the works of greenhouse effect?

Answer 7

1. Incoming solar radiation (in the form of short wave radiation).
   2a. Reflected by the atmosphere.
   2b. Absorbed by the atmosphere.
   2c. Reflected by the earth’s surface.
2. Radiation absorbed by the earth surface.
3. Heat is emitted from the earth’s surface in the form of long wave radiation.
4. Some radiation is released directly back into space.
5. Some long wave radiation is absorbed by greenhouse gases.
6. The long wave radiation is re-radiated back to the earth surface

Question 8

What are the human causes of global warming?

Answer 8

1. Concentration of greenhouse gases in the atmosphere increase.
2. Long wave radiation absorbed by the atmosphere increase.
3. More heat is trapped in the atmosphere and re-radiated back as counter-radiation.
4. Greenhouse effect intensifies.
5. Global average temperature increases.
6. Global warming.

Question 9

What are the human activities that affect carbon dioxide?

Answer 9

1. Burning of fossil fuels.
2. Deforestation.
3. Agriculture.
4. Garbage treatment.

Question 10

Elaborate on how burning of fossil fuels increase carbon dioxide.

Answer 10

These fuels, including oil, coal and natural gas, are the major source of energy used in power plants, industries and transport. Burning them emits large amounts of carbon dioxide.

Question 11

Elaborate on how deforestation increase carbon dioxide.

Answer 11

To provide land for agriculture and urban development, trees are often cleared through burning. This releases carbon dioxide into the atmosphere and reduces the number of trees that absorb carbon dioxide in the atmosphere.

Question 12

Elaborate on how agriculture increases carbon dioxide.

Answer 12

1. Livestock releases carbon dioxide during respiration.
2. Using fossil fuels in farming machines.
3. Burning organic waste in farms.

Question 13

Elaborate on how garbage treatment increases carbon dioxide.

Answer 13

Burning garbages in incinerators.

Question 14

What are the human activities that affect methane?

Answer 14

1. Agriculture.
2. Garbage treatment.

Question 15

Elaborate on how agriculture increases methane.

Answer 15

1. Livestock releases methane during the digestive process.
2. Wet rice farming/ paddy growing

Question 16

Elaborate on how garbage treatment increases methane.

Answer 16

Garbage decomposes in landfills releases methane.

Question 17

What are the human activities that affect nitrous oxides?

Answer 17

1. Burning of fossil fuels.
2. Agriculture.
3. Garbage treatment.
4. Manufacturing activities.

Question 18

Elaborate on how burning of fossil fuels increases nitrous oxides.

Answer 18

Burning these fuels in power plants, industries and transport emits nitrous oxides.

Question 19

Elaborate on how agriculture increases nitrous oxides.

Answer 19

Using nitrogen fertilizers in farming.

Question 20

Elaborate on how garbage treatment increases nitrous oxides.

Answer 20

Burning garbage in incinerator.

Question 21

Elaborate on how manufacturing activities increases nitrous oxides.

Answer 21

Producing nylon in factories.

Question 22

Elaborate on how manufacturing activities increases man made greenhouses gases.

Answer 22

Producing foams, refrigerants and solvents emits CFCs and HFCs.
Aluminium smelting and magnesium production releases PFCs and SF6.

Question 23

Generalize the lifetime of GHGs in the atmosphere.

Answer 23

In general, the lifetime of most of the GHGs in the atmosphere is long. The GHGs will continue to absorb heat as long as they are present in the atmosphere. Since they have a long lifetime, the global average temperature will keep on increasing for a long period of time.

Question 24

What are the natural causes of global warming?

Answer 24

1. Changes in solar output.
2. Changes in the amount of aerosols.
3. Changes in the shape of the earth’s orbit.
4. Changes in the tilt of the earth’s axis.

Question 25

Elaborate on changes in solar output as one of the natural causes of global warming.

Answer 25

When the sun emits more energy, solar radiation reaching the earth's surface will increase. This may lead to a rise in a global average temperature.

Question 26

Elaborate on changes in the amount of aerosols as one of the natural causes of global warming.

Answer 26

Aerosols are tiny particles released naturally, such as during volcanic eruption, or by human activity. They can reflect radiation back into space and therefore reduce the amount of solar radiation reaching the earth's surface.

Question 27

What does strong volcanic eruption releases?

Answer 27

1. GHGs e.g. water vapour. 2. Absorb more long wave radiation. 3. More heat is retained. 4. Increase in temperature.

Question 28

What does strong volcanic eruptions ejects?

Answer 28

1. Large amount of ash, dust and gases (small ash particles form a dark cloud shades sunlight). 2. Sulphur-rich gases (combine with water to form sulphuric acid aerosols and form a haze of tiny droplets that reflects incoming solar radiation) 3. Reduce the amount of solar radiation reaching the earth's surface. 4. Create a cooling effect.

Question 29

Elaborate more on the changes in the shape of the earth's orbit.

Answer 29

The shape of the earth's orbit changes from nearly circular to elliptical and then back again during a very long-term cycle. The earth experiences the greatest difference in air temperature when the earth's orbit is most elliptical

Question 30

Elaborate on the changes in the tilt of earth's axis.

Answer 30

The obliquity of the earth's axis changes over time, ranging from about 22.1 degrees to 24.5 degrees.

Question 31

What happens when there is low obliquity situation?

Answer 31

1. Cooler northern summers. -> Less melting of snow and ice. -> More snow and ice accumulate on the earth's surface. 2. Warmer northern winters. -> Warm air holds more moisture than cold air. -> More snowfall 3. Albedo of the earth's surface increases. 4. Solar radiation received by the earth's surface reduces. 5. Lower global average radiation.

Question 32

What happens when there is high obliquity situation?

Answer 32

1. Hotter northern summers. -> More melting of snow and ice. -> Less snow and ice accumulate on the earth's surface. 2. Colder norther winters. -> Cold air holds less moisture than warm air. -> Less snowfall 3. Albedo of the earth 's surface reduces. 4. Solar radiation received by the earth's surface increases. 5. Higher global average temperature.