7.2a Climate change causes

Question 1

What is the difference between weather and climate?

Answer 1

Timescale on which both are measured

Question 2

What are the similarities between weather and climate?

Answer 2

Both affected by:
- atmospheric circulatory systems
- oceanic circulatory systems
- clouds
- forest fires
- volcanic eruptions
- latitude
- altitude

Question 3

Climate change is a _______ process

Answer 3

Natural

Question 4

What factors cause natural climate change?

Answer 4

• Changes in solar radiation:
  –> varies due to changes in sun’s output
• Slow variations in the earths orbit
• Slow changes in angle of the earth’s axis
• Changes in the albedo of the Earth and atmosphere
• Changes in the longwave radiation returned to space:
  –> changing composition of atmosphere is a major forcing mechanism of climate change. Such changes have a significant impact on the longwave radiation returned to space.
• Carbon dioxide levels from geological time to present:
  –> carbon dioxide, temperature and other atmospheric phenomena have changed considerably over geological time. In the past concentrations have been much higher than the current value

Question 5

What is the definition of “climate change”?

Answer 5

The long-term shifts in temperatures and weather patterns.

Question 6

What is the definition of “global warming”?

Answer 6

“Increased greenhouse effect due to man releasing increased levels of greenhouse gases into the atmosphere, causing an increase in the temperature on Earth”

Question 7

What is the definition of the “Natural Greenhouse Effect”?

Answer 7

“Natural occurrence that raises temperature on Earth to a level that is habitable”

Question 8

What is the “enhanced greenhouse effect”?

Answer 8

–> Results from human activities that increase the concentrations of naturally occurring greenhouse gases
–> If there are more greenhouse gases less heat is lost, and thus the system changes in a dynamic equilibrium which may stabilise or reach a new equilibrium if a tipping point is reached
–> The tipping point is the level at which the effects of climate change become irreversible to varying degrees

Question 9

What does the 2014 IPCC (Intergovernmental Panel of Climate Change) state?

Answer 9

• ‘Warming of the climate system is unequivocal, and since the 1950’s many of the observed changes are unprecedented over decades to millennia’
• Atmospheric concentrations of carbon dioxide, methane and nitrous oxide have increased to levels unprecedented in at least the last 800,000 years
• Estimated there was a 95-100% likely that human influence was the dominant cause of global warming between 1951-2010
  –> Today (last 8 years) it’s commonly agreed that humans ARE (100%)

Question 10

What is radiative forcing?

Answer 10

“Radiative forcing means the change in the balance between radiation coming into the atmosphere and radiation going out of the atmosphere”

Question 11

What are some examples of positive forcing?

Answer 11

–> Greenhouse gases, tropospheric ozone, dark surfaces with lower albedo

Question 12

What are some examples of negative forcing?

Answer 12

–> Stratospheric ozone, aerosols in atmosphere, ice and snow with higher albedo

Question 13

What are some effects of positive radiation?

Answer 13

A positive radiation forcing tends on average to warm the surface of the earth

Question 14

What are some effects of negative radiation?

Answer 14

A negative radiation forcing tends on average to cool the surface

Question 15

What are some greenhouse gases?

Answer 15

• Water vapour
• Carbon dioxide
• Methane
• Nitrous oxide
• CFCs
• Ozone

Question 16

What are some sources that release Carbon Dioxide?

Answer 16

• Burning fossil fuels
• Deforestation
• Motor vehicle exhausts

Question 17

What are some sources that release Methane?

Answer 17

• Landfills
• Agriculture: intestines of cattle and sheep
  Wetlands, swamps, bogs
• Coal mines and natural gas

Question 18

What are some sources that release nitrous oxide?

Answer 18

• Fertilisers
• High temperature combustion of fossil fuels in industry

Question 19

What are some sources of CFCs?

Answer 19

• Expanders in plastic insulating foam
• Cleaners.
• Aerosol spray propellants
• Coolants for refrigeration and air conditioning.

Question 20

What is the source of ozone?

Answer 20

Formed in atmosphere
(nitrous oxides)

Question 21

Which greenhouse gases have the highest GWP (Global Warming Potential)?

Answer 21

Ozone - 1000
CFCs - 5000

Question 22

What do climate change sceptics believe in?

Answer 22

• Do NOT believe climate change is occuring
• Do not believe it is caused by humans
  –> EG. Martin Durkin

Question 23

What do climate change advocators believe in?

Answer 23

• Believe major reforms are required to stop emissions
• Believe climate change is predominantly human induced

Question 24

What is “global dimming”?

Answer 24

Global dimming: A substantial decline in the amount of solar energy reaching the Earth’s surface.

Air pollution has a cooling effect.

Natural particles in clean air provide points of attachment for water - forms a few large droplets with moderate reflectivity which eventually fall as rain. Polluted air contains far more particles than clean air (ash, soot, sulphur dioxide). Polluted clouds reflect far more light back into space, so preventing the sun’s heat from getting through to the earth’s surface.
–> because of this global warming may be greater than we actually experience it (as global dimming cools down the earths surface)

Question 25

How come polluted clouds reflect more light?

Answer 25

Natural particles in clean air provide points of attachment for water - forms a few large droplets with moderate reflectivity which eventually fall as rain. Polluted air contains far more particles than clean air (ash, soot, sulphur dioxide). Polluted clouds reflect far more light back into space, so preventing the sun’s heat from getting through to the earth’s surface.
–> because of this global warming may be greater than we actually experience it (as global dimming cools down the earths surface)