However with the burning of fossil fuels you can see that more CO2 is being released into the atmosphere unbalancing the equilibrium. Excess CO2 in the atmosphere causes one very big problem, “The Greenhouse Effect.”
Planet earth has a natural Greenhouse Effect. The Sun, which is the Earth's only external form of heat, emits solar radiation mainly in the form of shortwave visible and ultraviolet energy. Only 50% of this radiation reaches earth and heats its surface. The Earth reflects a lot of energy it has received from the Sun back to space. However, the Earth is much cooler than the Sun, so the energy re-emitted from the Earth's surface is much weaker. Greenhouses gases (CO2, CFCs, Methane, Water Vapour and Nitrous Oxide) trap this energy, just like the glass in a greenhouse traps longer wavelengths of energy but lets shorter lengths through, and therefore warms up the earth’s atmosphere. With humans burning fossil fuels, more CO2 is getting into the atmosphere and so fewer and fewer shorter wavelengths of energy are getting back out into space. The effect is that more energy is radiated back down to earth again inevitably raising earth’s global temperature. It is very important to remember that humans did not create the Greenhouse effect, they enhanced it.
The Greenhouse effect also creates positive feedback on the oceans. The Greenhouse effect makes global temperatures warmer, so more CO2 is evaporated from the sea enhancing the Greenhouse Effect even more.
Humans also enhance the Greenhouse effect by using spray deodorant cans. Spay deodorant cans contain CFCs (Chlorofluorocarbons) and when they are sprayed out of the can, they can easily find their way into the atmosphere. These are by far the most effective at absorbing energy and so measures should be taken to keep these emissions to a minimum.
Waste that humans produce is dumped at landfill sites. Over time this “rubbish” begins to decompose and during decomposition releases vast amounts of methane gas into the atmosphere. However, the waste could be used to generate electricity by burning it. Although this releases carbon dioxide into the air, it is not as strong a greenhouse gas as methane.
The problem of the Greenhouse Effect does not end here. The Greenhouse effect has been related to Global Warming, which many scientists believe the earth is enduring at this present moment. Although there is a strong link between the pollution caused by humans and Global Warming we can not relate them because it has not yet been proven.
Global Warming is basically a rise in temperature on the earth’s surface and by the year 2030 there is a predicted rise in average temperatures of between 1.5C and 4.5C. Although this seems not much, it would be enough to cause polar ice caps to melt and raise the sea levels. Weather patterns would also change, with perhaps more wetter climates, forcing ecosystems to change and the extinction of some species.
In this particular instance mankind has done a fairly damaging job, not only for the environment, but potentially for its own species. It is true that we are the environment.
Pictured above is the Nitrogen Cycle. Again the diagram is pretty self explanatory, but there are more ways that mankind can interfere with this natural cycle.
Soil erosion is a natural process. There are basically two ways in which soil can be eroded, wind and water. As water hits soil with impact it is said to be eroding it, equally when wind blows soil away with a strong force it is said to be eroding it. The human activity of deforestation increases soil erosion in several ways. Plants slow down water as it flows over the land (runoff) and this allows much of the rain to soak into the ground. Plant roots hold the soil in position and prevent it from being washed away. Plants break the impact of a raindrop before it hits the soil, thus reducing its ability to erode. Also plants act as a wind breaker stopping the force of the wind from blowing the soil away. Ultimately the link we are looking for between soil erosion and the nitrogen cycle is leaching. Leaching is also a natural process but humans significantly enhance it with activities like deforestation.
As we can see from the diagram there are various forms of nitrates in the soil. All these forms are very soluble in water. As a result nitrate ions are very easily washed out of the soil after a heavy rainfall. This is known as leaching. The water can then flow over the land (surface runoff) or infiltrate into the soil with the soluble nitrates where it can proceed to the nearest tributary or river. This then leads to Eutrophicaton a process which I will talk about shortly. The main thing about leaching is that the nitrates are lost from the soil. This therefore means that plants have less nitrogen to take up, so growth is poor and eventually plant organisms will die. One final point about leaching is there is an interesting link with the Carbon cycle. As I just mentioned plant organism will decrease so therefore there will be less photosynthesis and so more CO2 will remain in the atmosphere.
So following on from leaching and into Eutrophication, ions (primarily phosphates, Nitrates and Potassium) find their way into streams and lakes in various ways. As a result of these excessive elements, growth is encouraged and there is an algae “bloom.” Dead algae plants rise to the surface of the water where aerobic micro-organisms decompose the algae. Both the rapid algae growth and aerobic micro-organisms demand a lot of oxygen from the water. With no oxygen all organisms in this part of the river die, because they cannot respire. Also the algae bloom prevents light getting through to the plants below the surface of the water so they die because they are unable to photosynthesise. This reduces the levels of oxygen even more. So, because of the use of fertilisers to make a crop yield slightly better, an ecosystem, within a river, is completely destroyed.
Acid rain is a widespread term used to describe all forms of acid precipitation (rain, snow, hail, fog, etc.). Atmospheric pollutants, particularly oxides of sulphur and nitrogen, can cause precipitation to become more acidic when converted to sulphuric and nitric acids, hence the term acid rain.
The problem of acid rain is not a new one but the nature of the problem has changed from being a local problem for towns and cities to being an . Again it is important to remember that humans did not create acid rain, they enhanced it.
Precipitation is naturally acidic because of carbon dioxide in the atmosphere. The burning of (coal, oil and gas) produces and which can increase the acidity of rain or other precipitation. Sources of sulphur dioxide and oxides of nitrogen may be such as volcanoes, oceans, biological decay and forest fires, or may arise from combustion sources. The increasing demand for electricity and the rise in the number of in recent decades has meant that emissions of acidifying pollutants have increased dramatically from human sources, particularly since the 1950s. Emissions of such pollutants are heavily concentrated in the northern hemisphere, especially in and North America. As a result, precipitation is generally acidic in these countries.
Acid rain potentially brings environmental problems. In freshwater ecosystems the increased acidity of the river water can be related to the decrease in population of fish. Acidic conditions affect fish in a number of ways from the prevention of successful reproduction, to prevention of gaseous exchange in the fish’s gills.
Plant life is also affected by acid rain. It causes poorer growth, a discolouration of leaves and shallower roots.
Humans also can reap the effects of acid rain. Acid conditions in the soil release heavier metals such as lead and mercury which can contaminate drinking water and effectively poison humans.
“A virgin forest is where the hand of man has never set foot.”
Author Unknown
Another human activity that is severely damaging the environment, and also contributes greatly to the Greenhouse effect, is Deforestation.
If you look around you now, you are guaranteed to see at least one item that is made from wood. It is more than likely that a tree will have been cut down to create that product, meaning quite frankly less CO2 being released back into the atmosphere. Burning the wood also releases more CO2 into the atmosphere. It is also highly likely that a tree will not have been planted to replace the one that was chopped down. This is perhaps the most damaging activity that takes place because it is stopping the most natural way of CO2 getting back into the atmosphere. Deforestation levels are very high in Brazil in the Amazon Rainforest. However there are ways to stop deforestation levels increasing, like planting 2 trees for every one you chop down. Many tribes in the Amazon forest use slash and burn methods, where the tree is not fully chopped down, so that it is able to re-grow.
Deforestation ultimately increases the effect of soil erosion.
“Because we don't think about future generations, they will never forget us.”
Henrik Tikkanen
It is untrue that there is one solution to this whole problem. The vast majority of humankind has yet to realise the potential disasters that the earth faces. Fundamentally the human race has to be environmentally aware of the effects of the activities that they carry out before we can begin to think about a way to “cure” the environment if it is in fact “curable.”
One way to reduce pollution of the environment is by using clean, renewable fuels. Earlier on I mentioned the fact that once we have used up all our fossil fuels that will be it. However if we use a renewable source of energy, such as the sun’s energy mentioned in the quote above, we will be able to keep using it for generations to come. Unfortunately, as the quote is saying, humans are not bothered about developing a fuel for the future, they would much rather develop weapons of mass destruction to kill each other.
I will now move on to discuss what I feel are the best possible types of alternative energy sources.
“Have no doubt that we will be successful in harnessing the sun's energy.... If sunbeams were weapons of war, we would have had solar energy centuries ago.”
Sir George Porter, quoted in “The Observer,” 26th August 1973
Solar power is the term used to describe energy derived directly from the Sun. The Sun provides the basis of energy for all living things. Sunlight has been utilised by humans for drying crops, and heating water and buildings for thousands of years. Solar energy is free and will never run out. Today we can use solar panels to turn the Sun’s energy into useful energy. There are a number of different ways that we can utilise the Sun’s energy.
Passive solar heating involves the design of homes and other buildings to make full use of direct sunlight for heating purposes. Houses can be designed with large windows in the south facing walls and small windows in the north facing walls (it is the opposite south of the equator). This allows natural light and heat from the Sun to be used to its full potential and reduce the need for electricity.
Active solar heating includes the use of solar panels to heat large bodies of water mainly for domestic hot water systems, but also swimming pools. Photovoltaics allow the direct conversion of solar radiation into electricity by the interaction of light with the electrons in a semiconductor cell. As development in solar technology has increased, it has become much cheaper and the UK is starting to invest in the technology.
This alternative source seems nearly perfect but obvious problems can arise such as sunless days and the efficiency of the process. Also solar panels on roofs are aesthetically intrusive.
Another possible alternative energy source is wind power. Air moves around the Earth because of the differences in temperature and atmospheric pressure that exist. Wind turbines harness the movement of air to produce energy. They do not emit any greenhouse gases and air pollutants, apart from those involved in their construction. The wind turns the blades which turn a rotor shaft. The resultant mechanical power is used to drive an electricity generator. Wind turbines are often grouped together in wind farms. They offer a highly sustainable form of .
Wind power has very promising potential in the UK as it lies in the path of Atlantic depressions (low-pressure systems), which bring windy weather. The UK currently has over 70 onshore wind farms, and it is thought that wind power could be supplying 10% of the UK’s electricity by the year 2025.
It is estimated that the UK has a very large offshore wind resource. As well as being sited on land, the scope for setting up wind farms out at sea, where strong winds blow more consistently, is now under investigation. "Offshore" wind power, as it is called, involves fixing the bases of the wind turbines firmly to the sea bed and ensuring that the turbines can withstand the prevailing conditions, which are much more hostile than those on land. Currently there are 13 offshore wind farms in UK waters, most off the coasts of East Anglia, Lancashire and Cumbria.
Wind farms provide a clean source of energy, but they do have some disadvantages. To some, they have a detrimental visual impact (although I believe not) and can be noisy in windy conditions. Suitable locations for wind farms are often in areas of scenic beauty and so careful consideration needs to be given before they can be built. If more research into harnessing energy from the wind were undertaken, and better and more efficient wind turbines were produced it would appear that wind energy is perhaps one of the future sources of energy.
"Because electricity produced from nuclear sources generates none of the greenhouse gases associated with burning fossil fuels, nuclear power makes a substantial contribution to limiting such emissions."
- 'The Energy Report 1999', Department of Trade and Industry
The final alternative source of energy is already used today and I believe it to be the way forward for human civilisation, a way that is, if well maintained, environmentally clean and energy efficient.
Nuclear power has a significant part to play in maintaining a balanced energy policy. It currently contributes to 26% of the UK’s electricity generation and a great deal more in countries like France and Germany. Nuclear power generation does not contribute to air pollution and can therefore help to reduce acid rain and global warming. Nuclear power generation uses the fuel uranium to produce electricity. Uranium is a highly concentrated energy source that is available throughout the world in large quantities. 1 tonne of uranium can produce as much electricity as 2000 tonnes of coal. Once uranium has been used, it can be reprocessed and recycled to make more fuel. During the reprocessing, plutonium is given off as a by-product. The plutonium can then be used to generate power in fast reactors.
Electricity is generated in a nuclear power plant when an extra neutron is added to the nucleus of a uranium atom. This causes it to split apart and release heat energy. As the nucleus splits apart, several neutrons are released, which can then collide with another nucleus and cause further fission of uranium atoms. This leads to a chain of reactions. The heat produced during fission converts water to steam, which then turns a turbine and generates electricity. In a power station, the amount of energy release is controlled to provide an even heat supply.
Unfortunately, waste generated by the nuclear industry is radioactive and must therefore be disposed of with extreme care. As I said the radioactive material must be managed, to present no hazard to humans or the environment. The radioactivity of waste however, will decay over time. So with an overview of all the alternative energy sources, does nuclear power look like mankind’s best way alternative energy source, to prevent further destruction of the environment?
Written and researched by
Peter J Webster
