climate topic 2

Question 1

natural causes of climate variability

Answer 1

1. changes in earth’s orbit and angle of tilt
2. sunspot occurences
3. large-scale volcanic erruptions

Question 2

describe how changes in earth’s orbit and angle of tilt affect climate variability

Answer 2

ORBIT
1. orbit stretches from circular of elliptical shape and back again
2. when orbit is most elliptic, earth travels in a more oval shape
3. more radiation reaches earth at the planet’s closest approach to the sun than it does at the farthest departure from the sun

occurs every 100 000 years

TILT
1. earth’s axis varies back and forth between 21.5 - 24.5
2. when tilt decreases, hemispheres lean further away form sun
3. causes warmer winters and cooler summers
4. causes build up large ice sheets at higher latitudes which cool the earth

Question 3

describe how sunspot occurences affect climate variability

Answer 3

1. high sunspot activity = high amount of solar radiation
2. sunspots have lower temp, areas surrounding it radiate more energy to make up for the cooler sunspot areas
3. more solar radiation emitted = high temp on earth
4. periods of max sunspot activity corresponds with high annual temp on earth

each cycle = 11 years

Question 4

describe how large-scale volcanic erruptions affect climate variability

Answer 4

1. volcanic erruption releases large amounts of carbon dioxide, water vapour, sulfur dioxide, dust, ash into atmosphere
2. sulfur-based particles, dust and ash spread around the lower atmosphere area of the earth
3. the particles absorb and reflect solar energy back into space
4. temp. offsets greenhouse effect and lower temp

e.g. mount pinatubo in 1991 led to a drop in global temp of about 0.6 degrees celcius over 15 months after the erruption

Question 5

what is greenhouse effect?

Answer 5

• where greenhouse gases in earths atmosphere trap longwave radiation

1. shortwave radiation form sun travels to earth and is absorbed by earths surface
2. some SWR os absorbed and reflected by clouds
3. LWR from earth escapes
4. some LWR is absorbed by GHG and re-emitted in the atmosphere, keeping earth warm

Question 6

what is enhanced greenhouse effect?

Answer 6

1. more GHG in atmosphere, more LWR is absorbed and re-emitted
2. less heat escapes, temp increase

Question 7

how do anthropogenic (human) facotrs lead to enhanced greenhouse effect?

Answer 7

1. burning of fossil fuels
2. changing land use

Question 8

describe how burning fossil fuels lead to EGHE

Answer 8

1. FF have high carbon content
2. burning FF like coal produces high amounts of carbon dioxide and GHG
3. FF are burned to create energy for human activities like industries and urbanisation

e.g the use of fossil fuels has increased since 1880s, contributing to more than 35 billion tonnes of carbon dioxide emissions per year.

Question 9

describe how changing land use through deforestation can lead to EGHE

Answer 9

DEFORESTATION:
1. large scale removal forests for resources (building materials) and land for agriculture
2. reduce no. of trees that absorb carbon dioxide through photosynthesis
3. trees store carbon which is released when trees are cut down as carbon dioxide
4. clearing of treese exposes soil to sunlight, increase soil temp and rate of carbon oxidation

e.g. tropical deforestation contributes to about 20% of annual greenhouse gas emissions

Question 10

describe how changing land use for agriculture contributes to EGHE

Answer 10

• growing population, need space for agriculture to meet the rising demand for food
• burning fossil fuels to produce energy for farm machinery
• livestock rearing and natural decomposition processes release methane

e.g. contributes to about 30% of annual GHG emissions
- in paddy rice fields, decomposition is rapid due to the high amount of moisture in the soil, contributes to 5-20% of methane emissions

Question 11

describe how changing land use for industries lead to EGHE

Answer 11

• fossil fuels are burned to generate energy to run the machinery and factory processes
• contribute to 40% of GHG yearly

Question 12

describe how changing land use for urbanisation leads to EGHE

Answer 12

• fossil fuels are burned to power the high conc of vehicles and household activities like lighting, heating/cooling
• cities consume about 78% of the world’s enrgy and contribute significantly to the emission of GHG