Topic 6: The issue of global warming

external image global_warming1.jpg

6.1.1: Describe the role of greenhouse gases in maintaining mean global temperature.

external image gheffect.gif

Role of Greenhouse gases
  • Maintain mean global temperature
  • Normal and necessary condition for life on Earth
  • allow short wavelengths of radiation such as visible light and UV too pass through to the Earth's surface, but they trap the longer wavelengths such as infrared radiation

6.1.2: Describe how human activities add to greenhouse gases.

Human contribution
  • Burning of fossil fuel which release carbon dioxide
  • Deforestation affects earth’s ability to absorb carbon dioxide
  • Agriculture increase the methane level
  • Use of fertilizers lead to higher nitrous oxide
Carbon Dioxide Co2
Combustion, decomposition or respiration
Methane CH4
Anaerobic decomposition in rice fields and landfill, cow and stores under the arctic permafrost and oceans
Nitrogen Oxides, NOx
Internal combustion engines
Chlorofluorocarbons (CFC)
From fridge coolants and aerosol cans
external image diagram+co2+emissions+caused+by+human+activity.jpg

6.1.3: Discuss qualitatively the potential effects of increased mean global temperature.

Effect of global warming
  • Change in weather pattern
  • Melting of ice caps which would cause raise in sea level and hence flooding in coastal areas and possibility of water shortage
  • Agriculture may shift towards the poles
  • Human health can be affected by the spreading of tropical diseases
  • Increase in Drought and cyclones
  • Heavier precipitation events in most areas
  • Extinction of species in wild as many could not adapt to sudden climate change

external image impacts-mindmap.jpg

(For more info, go to page 8 of this document and read on)

6.1.4: Discuss the feedback mechanisms that would be associated with an increase in mean global temperature.

Feedback mechanisms
  • Positive feedback: increased thawing of permafrost, leading to an increase in methane levels which increase the mean global temperature

external image 3310511167_95258ecc57.jpg

  • Negative feedback: increase evaporation in tropical latitudes leading to increase snowfall on the polar ice caps, which reduces the mean global temperature

6.1.5: Describe and evaluate pollution management strategies to address the issue of global warming.

Management strategies:
  • Global: international agreement such as the Kyoto Agreement which aim to set a limit towards countries’ carbon emitting levels; Carbon taxes and Carbon trading
  • Local: eat locally produced foods and get involved in local political action
  • Personal: grow your own food and use energy-efficient products

(Preventive measures)
Carbon taxes
Require emitters to pay a free for every ton of greenhouse gases emitted
Carbon trading
Countries or companies emitting above the target level can buy carbon storage credits from clean developments or reforesting degraded land in other countries
Cap and trade
Permits to pollute above certain level are sold on the free market, any organization that is under allocation can make profit by selling the extra permits
Lifestyle changes
Individual actions to reduce climate change including choices of transport, energy use and consumer goods and services
Solar radiation management
Releasing atmospheric sulphates on a scale equivalent to large volcanic eruption or cloud seeding using sea water
Carbon dioxide reduction
Development of technologies to extract greenhouse gases from the atmosphere and store them
Building design
Improved air conditioning and circulation in building in the temperate zone
Emerging diseases
Monitoring and control of spreading tropical diseases
Coastal management
Improved sea defenses or managed retreat from low lying coastal areas

Things to consider when evaluating:
  • A full ratified Kyoto Protocol would achieve a reduction of warming by around 0.5 degree
  • Concerns about fair target setting between MEDCs and LEDCs continue to cause disagreement
  • International agreements affect large number of people
  • Countries may not sign or agree to international agreements
  • Concerns about the economic cost and impacts on development are widespread
  • Carbon storage in ecosystems are not well understood and difficult to monitor
  • Simulated volcanic eruptions are unpredictable and could damage the ozone layer
  • Adaptation methods do not require international co0operation
  • Emission mitigation attempts over two decades appear to have failed

external image Global-Warming.gif

6.1.6: Outline the arguments surrounding global warming.

Argument about global warming

  • Greenhouse gases can be produce by natural: volcanic activity; release of methane by animals and peat bogs; sunspot activity
  • Earth’s tilt and variation in orbit around the sun leads to seasonal and regional changes in temperatures
  • Ocean currents can lead to warming or cooling
  • Global dimming: the cooling effects of air pollution

Complexity of the Problem:
  • On a huge scale: atmosphere, the oceans and the land
  • Not all feedback mechanisms are fully understood
  • Many impact and processes are long-term

Uncertainty of climate models
  • How much is the planet warming
  • Where will the impacts of global warming be felt most acutely

external image sn0w-dees.jpg (alternate view to global warming) (great link for more info)

6.1.7: Evaluate contrasting human perceptions of the issue of global warming.

Consider the different view of 'ecocentric', 'authropocentric' and 'technocentric'.
external image Say-Global-Warming-Is-A-Myth-simpsons.jpg