2a. Humans have influenced the climate system

Question 1

Increase in global temperatures

Answer 1

• There’s been a consistent rise in global and + ocean temperatures in the 20th century
• From 1978, temperatures began to gradually rise up until 2014
• 2014 = warmest year fro average global land + ocean temperatures

Question 2

Shrinking valley glaciers & ice glaciers

Answer 2

• Glaciers can visually show us the rate of climate change through their rate of retreat
• Their retreat/growth can show regional & global indicators on climate change
• Comparing glaciers current size to their former size can identify short/long term trends

Question 3

Rising Sea Level

Answer 3

• Since 1990, the avg rise in sea level is 1 - 2.5 mm/year

Eustatic :
- Increased melting of ice sheets + glaciers (Antarctica + Greenland)
- Thermal expansion due to rising temperatures ( accounts fro 1/2 of the observed rise in sea level)

Isostatic:
- Variations in sea levels across the world due to the land mass re-bound (isostatic rebound)

Question 4

The Greenhouse Effect (Natural & anthropogenic)

Answer 4

• The natural greenhouse effect allows the earth to self-regulate & react to the changing vol of atmospheric GHG’s
• Anthropgenic greenhouse effect causes sudden disruptions to the earth, putting it out of equilibrium
• Constant input of GHG’s will push the earth over the tipping point

Question 5

Reasons for rising emissions since the pre-industrial era: Land Use change

Answer 5

• Account fro 1/3 of GHG emissions
• 40% of change = agricultural
• 25% of global forest lost since 1700
  Example: Amazon basin - 80% of deforestation is due to agriculture + plantations

Question 6

Reasons for rising emissions since the pre-industrial era: Globalisation

Answer 6

• Increased flows of migration
• National + international travel
• Increased number of goods air freighted
• Carbon footprint of planes = x29 higher than trains

Question 7

Reasons for rising emissions since the pre-industrial era: Carbon footprint

Answer 7

• Imports/exports
• Manufactoring
• Power stations
• US = largest global carbon footprint
• Avg US household produces 50 tonnes co2 per year = x5 greater than the global average
• 87% of global energy production is from burning fossil fuels

Question 8

Reasons for rising emissions since the pre-industrial era: Population Growth

Answer 8

• 1800 = 1bn
• 2015 = 7.4bn
• Development of EDC’s
• Increased population = increased consumption = increased production + imports/exports of goods
• Consumerism
• Urbanisation
• Increased incomes = increased demand

Question 9

How do humans influence the global energy balance?

Answer 9

• Global energy balance alters due to the increased input of GHG’s into the atmosphere by humans
• Increased outgoing long wave energy (Heat) is absorbed and returned to the earths surface = increased temperatures
• Higher evaporation rates due to high temperatures
• Increased latent heat transfers to the atmosphere in water vapour = GHG = further alters the energy balance
• Rising temperatures, decreases albedo due to melting ice sheets so heat energy is absorbed by dark surfaces

Question 10

Case Study: AC = UK
- Their contribution to anthropogenic GHG emissions overtime

Answer 10

Why are the total emission in the UK falling?
- British government pushed to decarbonise the British economy = increased reductions in future carbon emissions
- Joined the Paris agreement (aim to keep global temperatures <2 degrees)
- Decreased internal manufacturing of goods - most sourced from Asia

Why the UK has reduced its dependance on Coal?
- Improvements in energy conservation = increase efficiency in buildings
- International agreements + obligations forced changes in emissions
- Development of nuclear power stations (1970’s)
- increased sources of renewable energy (1090’s)

Question 11

Case Study: EDC = China
- Their contribution to anthropogenic GHG emissions overtime

Answer 11

Why is China dependant on Coal?
- large indigenous reserves = cheap
- Large population + industrial demands
- Many western companies have their goods produced in China as its cheaper
- Globalisation =increased demand
- TNC’s move to china to produce goods

International agreements:
- Except from these e.g Kyoto (1990’s)

• Increased rural - urban migration in the past 40yrs
• Chinas economic growth is based on manufacturing + exports of goods