Atmospheric Process - Climate Variability

Question 1

Absorption of Radiation from the Sun

Answer 1

• Absorption of radiation from the sun
o E.g. trees melting snow around their bases
• Trees are better absorbers and therefore will retain more heat and hence, will melt the snow
o Solar energy is both absorbed and reflected by the earth
o With greenhouse effect: (added infrared energy from the greenhouse layer raises temp)

o Without Greenhouse effect:

See notes for diagrams

Question 2

Earth-atmosphere energy balance

Answer 2

See notes

Question 3

Globally

Answer 3

o Temperature
• Evidence showing that earth’s climate has warmed over the past century
• Climate indicators: temperatures over land and in oceans, sea level
• Evidence that changes are consistent with changes expected from increase of greenhouse gases
o Sea level rise
• Have always been large fluctuations of sea level in history
• Rising at around 3.2 mm/year (opposed to 1.7 mm/year in 1990s)
o Atmospheric CO2
• Cycles due to seasonal variation in photosynthesis impact CO2 uptake by plants (i.e. growing season = less CO2 in atmosphere)
o GHG emissions = increased atmospheric GHG concentrations = warmer planet
o Very likely that warming of the planet is due to greenhouse gas emissions caused by human activity

Question 4

Natural Cycles

Answer 4

o Continental movement
• Rate at which plate tectonics move can influence global climate
• Rapid spreading = increased volcanic activity = increased CO2
o Orbital variation
• Orbit, obliquity, eccentricity, precession

Question 5

Feedbacks in the system

Answer 5

o Positive feedback
• E.g. oceans: warmer oceans may release more CO2 than is dissolved, therefore enhanced GH effect
• E.g. polar ice caps: warmer climate melts ice cover, which reflects sunlight and lets earth absorbed more heat, therefore enhanced GH effect
o Negative feedback
• E.g. oceans: more water vapour means more cloud cover and more sunlight reflected, therefore reduced GH effect
• E.g. polar ice caps: breakup of ice cover, increase evaporation, increased snow and deposition, if deposition area is greater than break up area exposed, reflecting area increases, therefore reduced GH effect

Question 6

Climate Change Impacts

Answer 6

o Island nations
• Reef bleaching effects
• Rising sea levels impact on island water resources and hence sustainability
o Agriculture
• Potential for erosion, salinity problems, loss of fertile soil, water availability

Question 7

Adaptation

Answer 7

o Conversation: enhance resilience of ecosystems
o Coastal erosion: coastal defences
o Heatwaves: support for those at risk
o Energy supply: heat tolerant transformer, reduced demand
o Fisheries: reduce overfishing
o Food production: drought tolerant cultivars
o Coastal flooding: flood-tolerant designs, flood barriers
o Fire: fireproof building designs, early warning systems
o Reduce GHG emissions
• Slow response of global climate system means current increases in GHG concentrations will already bring about irreversible changes
• Therefore, not a short term solution