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9.4 Caring for the country: 6. The effects of industrialisation
Syllabus reference (October 2002 version) |
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6. The results of the Industrial Revolution on the atmosphere and hydrosphere |
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Students:
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Extract from Earth and Environmental Science Stage 6 Syllabus (Amended October 2002). © Board of Studies, NSW
[Edit: 15 July 09]
Prior Learning: Science Stages 4-5 Syllabus 4.9.4b and 5.10c and Preliminary module 8.2.4 and 8.2.5
Background: Before the Industrial Revolution, industries were mostly cottage industries with animals such as horses or bullocks, or humans providing the energy. Transport was by walking or horse and buggy. The Industrial Revolution brought steam trains and factories that burnt wood or coal to supply energy. This was later followed by petrol, diesel, gas and oil as energy sources as well as the use of coal for much of the electricity generation. Practices of the Industrial Revolution greatly increased the carbon dioxide output into the atmosphere and increased the production of acid rain in many locations.
Chlorofluorocarbons (CFCs) were originally chosen as a propellant for spray cans and as refrigerants in air conditioners because they are so inert and therefore will not react with other chemicals. The inertness of CFCs allows them to drift up to the stratosphere unchanged. In 1976, scientists discovered that there was a reduction in ozone above the Antarctic. They realised that chlorofluorocarbons and other halides were contributing to this reduction. The ozone is very important in the stratosphere as it reduces the amount of ultra-violet (UV) light that reaches the surface of the Earth. UV light is a major cause of skin cancer. Practices have been implemented to reduce the release of these gases into the atmosphere.
gather and analyse information from secondary sources on the composition of emissions from vehicle exhausts
- You could gather information by checking with the
RTA
. The Roads and Traffic Authority does emissions testing in NSW.
The Federal government developed a test for diesel emissions from cars and trucks in September 2000. It could dramatically improve air quality in Australia's cities. It can be used to identify high polluting vehicles for repair.
- Analyse the information you have gathered. Are some fuels less polluting than others? Which fuels should be used if greenhouse gases are to be reduced? Are there other factors to consider?
analyse, process and present information to identify the origins of greenhouse gases and acid rain from both natural and made environments and use available evidence to propose possible local and global strategies to achieve decreased emission of carbon dioxide, methane and sulphur dioxide
- To analyse data, you need to first gather information. Information can be gained from written and visual materials. Many science books provide the information required. Look in books in the library about the environment and make notes about the gases that contribute to the enhancement of the greenhouse effect. Check on the Internet and see if there is more recent information that has come to light about greenhouse gases that does not agree with the other sources. Do the same for information on acid rain. Be sure to include information about natural processes, such as methane production in swamps that have anaerobic conditions and methane produced naturally by animals. Are there any recent human events that have contributed to greenhouse gases or acid rain? Your teacher might like to invite a speaker from Greenpeace, the Total Environment Centre or the Nature Conservation Council to speak about these issues.
A website that explains the origins of greenhouse gases is Enhanced Greenhouse Effect- a hot international topic Australian Academy of Science, Nova. Scroll down to Box 1 Greenhouse gases.
- Gather the information required and process it under appropriate headings, such as that shown below. Include carbon dioxide, sulfur dioxide, nitrogen oxides (NO, NO2 and N2O) and water vapour.
Gas Natural origin
Origin from made environment
Contribution to greenhouse
Causes acid rain
carbon dioxide
respiration in animals
burning of fossil fuels
yes
yes
- You now need another table for the strategies to achieve reduced emissions of each gas. Can you reduce emissions from natural environments? Should you be trying to reduce these? Are these constant over long periods of time?
Divide your table into local and global strategies. Which one is it easier to have some effect on? How can we as individuals or organisations affect global issues?
- Decide how you are going to present your information to the class or to a wider audience. You might find it useful to develop simple concept maps that demonstrate cause and effect relationships, without and with the strategies you suggest.
- Use the evidence you have collected to propose possible local and global strategies to achieve decreased emission of each gas.
summarise types of chemical reactions involved in the formation of greenhouse gases and acid rain from the burning of fossil fuels (word equations only)
Formation of Greenhouse Gases
- Combustion of carbon (coal) and hydrocarbons (petroleum and natural gas) in fossil fuels is the major source of the main greenhouse gases, carbon dioxide (CO2 ) and carbon monoxide (CO).
Formation of acid rain
- The equations for the formation of acid rain include the three different sources of acid rain: sulfur dioxide, nitrogen dioxide and carbon dioxide. These gases react with moisture in the air, such as rain and fog. The first two are derived from impurities in fossil fuels.
analyse different scientific views on the causes of global warming to assess predictions on the likelihood of global warming
- Most scientists in the climate change field believe that rises in carbon dioxide emissions and other gases such as methane and nitrous oxide have been directly responsible for rises in global temperatures. However, there are a few scientists who argue that this temperature rise could just be part of natural fluctuations in the absorption and emission of such things as methane gas.
- There are a number of different scientific views on the causes of global warming but the overwhelming scientific opinion is that greenhouse gas emissions such as the ones listed above are rising and this is due to human activity. The main gases and their sources are:
Carbon dioxide-Since 1850, there has been a mean rise in global temperature of approximately 0.74 ± 0.18 °C with most of this increase since 1960. Carbon dioxide levels have risen from 280 ppm in 1850 to 390 ppm in 2009. Since the Industrial Revolution human activities have seen massive amounts of fossil fuel being burnt to generate electricity, fuel furnaces and operate smelters. Other causes of rising CO2 today are cement manufacture, land clearing, forest harvesting and changes in agricultural practice. These, combined with the burning of fuel in motor vehicles, has resulted in massive amounts of carbon dioxide being emitted into the atmosphere. According to the National Greenhouse Gas Inventory of 2005, CO2 accounts for 74.3 per cent of Australia's greenhouse gas emissions.
Methane: Given that methane has eleven times more warming potential than carbon dioxide, processes affecting the release of methane into the atmosphere should be given great consideration. Massive amounts of methane are currently stored in clathrates, also known as gas hydrates, which occur abundantly in nature. Clathrates occur as a result of organic matter decomposing and the methane that results becoming entrapped. Most of the methane gas is trapped in ocean sediments. However, some methane is trapped in ice in Arctic regions and regions in the tundra. The worldwide amounts of carbon bound in clathrates are conservatively estimated to total twice the amount of carbon to be found in all known fossil fuels on Earth. The methane trapped as clathrates in ice can be released into the atmosphere. This happens after ice sheets melt or in the case of clathrates layers in ocean sediments, the pressure of the water above them is reduced.
- It is difficult to develop accurate computer models to predict the effect on climate due to the large number of variables involved with the greenhouse effect. For example, the effect of cloud cover: clouds reflect the incoming light and absorb outgoing infra-red radiation. The magnitude of its effect depends upon the degree of cloud cover, its altitude and thickness. Scientists views on the effect of cloud cover vary from no greenhouse effect to a mean 2oC temperature rise over 100 years.
- Debate about global warming centres on the following points:
Is there a greenhouse effect? A few scientists reject this theory, claiming that the global warming that is currently observed is predictable as a natural cyclic process of the Earth but most scientists, especially those who work in the field of atmospheric science and climate change, agree that the enhanced greenhouse effect is resulting in serious climate change.
Some scientists indicate that the rate of release of greenhouse gases must be reduced. There is concern that the rate of reduction that is desired may not be achieved by enough nations to have a global impact.
A number of global climate models have been developed that assist scientists to make predictions about the effects of global warming. However, there is concern by some scientists that these models may not be accurate enough for policy makers to determine what actions should be taken.
Reducing Greenhouse Gas Emissions CSIRO, Climate Change
Emissions monitoring The Australian Greenhouse Office, Canberra
Listen to Professor Ian Plimer, who wrote the book Heaven and Earth and then read what Mike Pope said about the book. Part 1 Professor Ian Plimer interviewed by Brian Carlton: Heaven and Earth ABNNewswire, May 26, 2009 on Youtube and Heaven and Earth and science fiction Opinions by Mike Pope, Science Alert, 28 June, 2009
gather and analyse information from secondary sources to evaluate
- one international strategy aimed at reducing ozone depletion
- one international strategy aimed at reducing human causes of global warming
- Gather information from journals and the Internet on an international treaty aimed at reducing ozone depletion. Look for journals in the school library and if you have no luck try the local town or municipal library. When using the Internet try several search engines. The main treaty signed was the Montreal Protocol and it should be easy to find information about this treaty. Find information such as when it was signed, why there were different targets for developed and developing countries and if most countries were able to meet their targets. Were there any problems associated with countries complying?
- Analyse the information by arranging it in a way that enables evaluation of the strategy. What methods were used to assist in countries complying with the targets?
- Gather information from journals and the Internet on an international strategy aimed at reducing human causes of global warming. If you are using a search engine insert words such as 'enhanced greenhouse effect', Kyoto Protocol, 'global warming'.
Find information such as where and when was the Framework Convention on Climate Change signed and how many nations signed it? What was its object? Were definite targets decided on and were penalties set up for countries that didn't comply? Why or why not? How many countries have presently ratified it? Australia ratified the agreement in December, 2007, when the Rudd Labor government, was in power.
This United Nations
gather information from secondary sources to summarise the uses of CFCs and other halides and describe the ways in which their use is being phased out and alternative products being used
- Look on the Internet to gather information on the uses of CFCs.
What ozone is and what effect CFCs are having on it
- CFCs were used as refrigerant fluids, solvents, aerosol propellants and blowing agents in the fabrication of foam plastics. They are being phased out in accordance with the Montreal Protocol (agreed to in 1987 and tightened in 1990 and 1992). It was aimed at decreasing production and consumption of CFCs to 50% of 1986 levels by 1998. Most developed signatory countries have exceeded these levels.
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Protecting the Atmosphere, Ozone protection
Review of performance: Outcome 1-Environment, Department of the Environment and Heritage Annual Report 2003-04Alternatives to CFCs are HCFCs (Hydrochlorofluorocarbons) and HFCs (Hydrofluorocarbons). These are not as stable as the CFCs because the hydrogen-carbon bond breaks down more easily, so they don't reach the stratosphere. Moreover, they do have a lesser effect on the ozone layer. Unfortunately they seem to be greenhouse gases.
Car manufacturers are now producing air conditioners using the more environmentally friendly gas, R-134a, as a refrigerant. Older air conditioners that once used the CFC based gas, R-12, are being converted.
Most aerosol cans have not used freon as a propellant for almost twenty years. Many of the companies have now switched to using pump action spray bottles or using compressed nitrogen as the propellant.
outline the way in which chlorofluorocarbons and other halides can reduce the percentage of ozone in the stratosphere
- CFCs in the stratosphere, in the presence of UV light and low temperatures, breakdown to release a chlorine atom. The worst affected areas are the poles, especially Antarctica.
- The following equations are examples of how two CFCs, CFC-11 and CFC-12, release chlorine in UV light.
- Once the chlorine is released, it reacts with ozone to give off chlorine oxide, ClO, as it breaks the ozone down to oxygen. Chlorine oxide then reacts with oxygen atoms to yield atomic chlorine again. In this way the reaction continues.
- The overall result is:
, catalysed by Cl and ClO. Thus the ozone is continually broken down, in a cyclic fashion.
- Other industrial chemicals such as carbon tetrachloride (CCl4) and methylchloroform (CH3CCl3) also have the same effect as CFCs by releasing chlorine into the upper atmosphere.
- Compounds with bromine have been used in such appliances as fire extinguishes and are used for pest control. Since bromine has recently been shown to deplete ozone, fire extinguishes containing bromine have now been banned.
- Volcanoes can emit large quantities of gases which contain sulfates and chlorine. NASA reported that the ozone layer in the tropics was approximately 10% thinner than normal in January 1992. The cause was thought to be the Mt Pinatubo eruption in the Philippines.
Earth's sunscreen- the ozone layer
Australian Academy of Science. Box 4: Australia finds a replacement for methyl bromide.
summarise the evidence for ozone depletion and the role of Australian scientists in this ongoing research
- Some US scientists predicted in 1976 that there would be a depleting of the ozone layer, based on their knowledge of CFCs. Ozone depletion was confirmed in the early 1980s when CFCs were found in the stratosphere. Scientists then checked back over data collected and found that the ozone levels over the Antarctic had been stable until the late 1970s.
- Severe depletion of ozone over the Antarctic has been occurring since 1979. Global ozone levels declined by about 3% between the late 1970s and early 1990s, three times faster than recorded in the early 1970s.
- The Antarctic ozone hole is mapped by the Total Ozone Mapping Spectrophotometer (TOMS), carried on satellites and aircraft.
- Australian scientists are among the most efficient in the world when it comes to finding causes of ozone depletion as well as finding alternatives to chemicals found to reduce the amount of ozone in the atmosphere.
- In Cape Grim in Tasmania, a team of scientists working for the CSIRO collect some of the most pristine air samples in the world. From these samples, the scientists can determine which pollutants are present in the atmosphere. The team has discovered that the ozone depleting gas, halon 1202, although it only has an ozone depletion potential of about half that of common CFCs, is in fact increasing in abundance of about 17% per year. Halon 1202 could be a by-product from the production of other known halons, or it may be being made deliberately for military applications.
The work of Dr Paul Fraser, an Australian scientist
CSIRO, Atmospheric research Dr Jonathan Banks is an Australian scientist that worked for the CSIRO. In 1997, Dr Banks received the Best-of-the-Best Stratospheric Ozone Protection Award from the United States Environmental Protection Agency (US EPA). This award was in recognition of his leadership in protecting the Earth's ozone layer. Dr Banks was the inaugural chairman of the international Methyl Bromide Technical Options Committee (MBTOC), which first met in the Hague in 1993. Methyl bromide is a fumigant that has been identified as a significant cause of ozone depletion in the atmosphere. In 1995, the committee delivered a major report recommending ways to limit methyl bromide use, which was adopted by the nations that signed the Montreal Protocol. The MBTOC report included important features directly attributable to Dr Banks' input and chairmanship. It is regarded as an important source document containing much original data and has been widely quoted.
A problem with halons CSIRO, Atmospheric research, Media release, Major
setback to ozone layer recovery.
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