8.6.1 Describe some possible models of global warming.
Milankovitch cycles
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Volcanic activity
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Solar flare activity
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Carbon dioxide emissions
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8.6.2 State what is meant by the enhanced greenhouse effect.
The enhanced greenhouse effect is the increasing of the greenhouse effect due to mankind.
8.6.3 Identify the increased combustion of fossil fuels as the likely major cause of the enhanced greenhouse effect.
Although debatable, it is highly likely that human activity -- namely the burning of fossil fuels -- is responsible for the enhanced greenhouse effect. The use of fossil fuels increases the amount of greenhouse gases released into the atmosphere, which are known for contributing to the greenhouse effect.
8.6.4 Describe the evidence that links global warming to increased levels of greenhouse gases.
According to Vostok Ice Core data and various climate models, the current temperature and carbon dioxide levels are higher than they have ever been for the past 420,00 years. There is a clear correlation between the amount of carbon dioxide in the atmosphere and global temperature.
8.6.5 Outline some of the mechanisms that may increase the rate of global warming.
The enhanced greenhouse effect has mostly been attributed to:
- The burning of fossil fuels, which release greenhouse gases into the atmosphere.
- The reduction of ice/snow cover due to global warming, which reduces albedo and increases the rate of heat absorption.
- Reductions in the solubility of carbon dioxide in the sea due to increases in temperature, which increase atmospheric carbon dioxide concentrations.
- Deforestation reduces carbon fixation by plans, which in turn increases carbon dioxide concentrations.
8.6.6 Define coefficient of volume expansion.
The coefficient of volume or cubical expansion is the fractional change in volume per degree change in temperature, given by the equation:
Where V0 is the original volume, delta V is the volume change, delta T is the temperature change and ß is the coefficient of volume expansion. This value is typically expressed in 10^-4 per degrees Celsius.
8.6.7 State that one possible effect of the enhanced greenhouse effect is a rise in mean sea-level.
One predicted effect of the enhanced greenhouse effect is a rise in mean sea level.
8.6.8 Outline possible reasons for a predicted rise in mean sea-level.
A rise in mean sea level can occur due to:
A change in sea level is normal and occurs naturally, however, the enhanced greenhouse effect is a newly developed cause. The change in sea level has, as a result, reached an unnatural rate. Some reasons why this prediction is difficult to make include:
- Atmospheric pressure
- Plate tectonic movements
- Wind
- Tide
- Flow of rivers into the sea
- Changes in water salinity
A change in sea level is normal and occurs naturally, however, the enhanced greenhouse effect is a newly developed cause. The change in sea level has, as a result, reached an unnatural rate. Some reasons why this prediction is difficult to make include:
- The anomalous expansion of water (water will expand above 4 degrees Celsius and contract below 4 degrees Celsius, hence, rises in sea level only occur at a certain temperatures)
- Differences between ice melting on water as opposed to land (when ice on the sea (ie. icebergs) melts, the water replaces the area where the ice used to be, therefore there is no change in sea level)
8.6.9 Identify climate change as an outcome of the enhanced greenhouse effect.
Due to the rises in temperature, the earth's climate has changed significantly.
8.6.10 Solve problems related to the enhanced greenhouse effect.
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8.6.11 Identify some possible solutions to reduce the enhanced greenhouse effect.
Some steps have been taken to reduce the enhanced greenhouse effect. These include greater efficiency of power production, replacing the use of coal with natural gas, use of combined heating and power systems (CHP) -- where excess heat from electricity is used to heat the home, increases in use of renewable energy sources and nuclear power, carbon dioxide capture and storage and use of hybrid vehicles.
8.6.12 Discuss international efforts to reduce the enhanced greenhouse effect.
Political steps have also been taken to aid in the reduction of global climate change. These include the intergovernmental panel on climate change (IPCC), kyoto protocol and asia-pacific partnership on clean development and climate (APPCDC).
- The IPCC is the leading international body for assessment of climate change. It was established by the united nations environment program (UNEP) and world meteorological organization (WMO) to provide the world with scientific reasoning on climate change and its potential impacts. It reviews and assess the most recent scientific data produced worldwide to further understand climate change. It is open to all members of the UN and currently 195 countries are signed.
- The Kyoto Protocol is an international agreement linked to the united nations framework convention on climate change. This agreement sets binding targets for the 37 industrialized countries and the european community regarding greenhouse gas emissions. Kyoto mechanisms include emissions trading ("carbon market"), clean development (CDM) and joint implementation (JI).
- The APPCDC was an international, voluntary public-private partnership between Australia, Canada, India, Japan, the People's Republic of China, South Korea and USA in 2005. These members account for over 50% of the world's greenhouse gas emissions, energy consumption, GDP and population. Unlike the Kyoto protocol, which imposes mandatory limits on greenhouse gas emissions, this partnership engages member countries to accelerate the development and deployment of clean energy technologies, with no mandatory enforcement mechanism.