Climate change (Causes)

Question 1

Define climate change

Answer 1

• long-term variation/climate patterns
• warming, cooling of temp
• precipitation
• wind patterns

Question 2

Natural causes of climate change

Answer 2

• variation in solar input

- volcanic eruptions

Question 3

Variation in solar input

Answer 3

• varying solar radiation due to changes to its magnetic field
• affects no. of sunspots (cooler regions on surface, dark spots)
• areas arnd sunspots radiate more energy to compensate
• more sunspots, higher temp
• no. of sunspots rise and fall in 11 year cycles

Question 4

Volcanic eruptions

Answer 4

• erupt, large amts of CO2, water vapour, SO2, dust, ash released into atmosphere
• SO2 reacts with water, for sulfur-based particles
• tgt with dust and ash, reflect solar energy back to space, temp go down regionally/globally
• e.g. land volcanoes estimated to emit 242 million tonnes of CO2 per yr, humans 29 billion tonnes \
• short term effect, volcanic ash would eventually settle

Question 5

Man-made causes

Answer 5

• Deforestation
• Agricultural activities
• Urbanisation
• Industrial activities

Question 6

Deforestation

Answer 6

• large scale clearance of forests for reasons e.g. making paper products, clearance of land (mining, agriculture)
• plants absorb CO2 during photosynthesis, less plants, more CO2 in air
• soil is large carbon sink, due to organic matter like dead leaves and animals
• deforestation expose soil to sunlight, increase soil temp, increase rate of carbon oxidation
• increase rate at which CO2 is released frm soil into atmosphere
• more heat trapped, temp increase
• e.g. 11000 km2 of Amazon Rainforest destroyed (aug 2019 to july 2020)

Question 7

Agricultural activities

Answer 7

• practice of cultivating land, producing crops, raising lifestock
• use of inorganic fertilisers, increase amt of nitrous oxide in soil thru ploughing, when rain flows thru soil
• machines e.g. tractors run on soil, release CO2
• organic matter ie dead leaves, animals release methane during decomposition
• methane released frm cattle during digestion
• abt 120kg of methane per cattle released per year

Question 8

Urbanization

Answer 8

• increase in proportion of population living in towns, cities within a country/region
• large amts of fossil fuels are burnt to provide energy for household activities ie. heating,cooking, electricity
• high conc of cars, buses etc increase emission of greenhouse gases
• 35% of SG population use private cars `

Question 9

Industrial activities

Answer 9

• industrial economic activities (ie. secondary industries like manufacturing) often involve burning of fossil fuels
• release greenhouse gases (CO2, nitrous oxide, methane)
• largest contributor is power plant industry
• some gases also released as by products when goods are produced
• e.g. manufacturing a mobile phone releases 60kg of CO2 equivalent, computer 275kg CO2 equivalent