The greenhouse effect is a natural process and one that is vital to the existence of humans. Without the greenhouse effect the earth will be significantly colder and unable to support large scale life. The greenhouse effect acts as a kind of blanket. As energy is reflected or released by the earth it moves into the atmosphere where it is trapped and reflected back by a layer of greenhouses gases. The reflected energy returns to earth and is absorbed warming global temperatures. The problem of global warming is caused by humans enhancing the greenhouse effect. We are releasing more greenhouse gases into the atmosphere which is trapping an ever increasing amount of reflected or released energy which returns to earth and warms us further.
Greenhouse gasses (GHG): Any gas that absorbs and emits radiation in the thermal infrared range. The gases include: Carbon monoxide, carbon dioxide, methane, sulphur dioxide, Nitrous Oxide, water vapour and ozone.
Sources of greenhouse gases include:
There are some natural causes of changes in climate including:
||Mitigation: Trying to reduce the effects of something happening.
Adaptation: Changing lifestyles to suit new conditions.
Improved Arctic Navigation: Global warming will mean that the amount of Arctic ice steadily decreases. As the ice melts navigation across the North Pole will become safer and quicker. Trade between Scandinavia, Russia, Canada and US will all be a lot easier.
Increased Agricultural Land: As permafrost melts and temperatures start to rise it will be possible to grow more crops on more land. With a rising global population this might be vital in the fight to reduce global famine.
Reduction in Cold Deaths: Old, young and sick people are very vulnerable to the cold. If global temperatures start to rise then latitudes further north and south will become more hospitable and less people will die from the cold.
Release of Freshwater: Currently a lot the world’s freshwater is held in glaciers or as permafrost. As global temperatures rise, we might be able to capture and use some of this freshwater to reduce the effects of drought.
Accessibility of Resources: It is believed that places like Greenland, Alaska, Siberia and Antarctica contain a lot of resources (oil, gas, etc.). As global warming causes large areas of ice to melt they will become more accessible for human exploitation.
Reduced Heating: If global temperatures rise people will have to heat their properties less. Not only will this save money but it will also reduce the demand for gas and electricity and therefore reduce the amount of greenhouse gases being released.
Acid rain was first discovered in Manchester, UK in 1852, but it was not properly studied until the 1960’s. Acid rain can take two forms, wet deposition and dry deposition. Wet deposition is when pollutants mix with rain water and fall to the ground as acidic precipitation. Dry deposition is when pollutants and particulates fall to the ground without mixing with rain water. Some acid rain has had pH levels as low as 2
Sulphur dioxide and nitrous oxides are the two main chemicals that react with water to make acid rain. The chemicals are commonly released from power stations, factories and transport. Traditionally sulphur dioxide has been the biggest contributing chemical, accounting for about two thirds and nitrous oxides the other third. However, in most areas of the world the importance of sulphur dioxide is decreasing and nitrous oxides increasing. Acid rain can cause many problems including:
Acid rain is known as a transboundary pollutant because it can be blown from one country to another – it does not obey national boundaries and in fact it is often non polluting countries that are most seriously impacted. Because it is a transboundary polluter acid rain tends to be worst in the direction of the prevailing wind from major industrial locations. The map to the right shows that the east coast of the US suffers badly from acid rain, its rain has an average pH of 4. Large parts of Europe and also the east coast of China are also badly affected.
Acid rain can be reduced by reducing the amount of fossil fuel burnt or at least burning coal with a lower sulphur content, by using a greater proportion of renewable energy, by using more public transport and cleaner forms of transport and by removing pollution at source with the use of scrubbers.
Dry Deposition: When acid falls directly back to earth without mixing with precipitation. This tends to happen close to source.
Wet Deposition: When acids are dissolved in precipitation and fall to the ground as acid rain.
The ozone layer is a layer of gas (mainly ozone O3) high in the Earth’s atmosphere (20-30km up). The ozone layer helps to protect humans from the sun’s harmful ultraviolet solar radiation (it absorbs up to 99%). The existence of the ozone layer was first discovered in 1913. The ozone layer can be damaged by chemicals and gases including; nitrous oxide, bromine and chlorine. Although all occur naturally the amount of chlorine and bromine were increasing because of the human use of CFCs (chlorofluorocarbons) and bromofluorocarbons. CFCs were being used in products like:
Even though it was known that the ozone layer could be damaged, it was not until 1985 when holes were discovered over the poles that serious action was taken. This meant that more of the sun’s harmful ultraviolet radiation was reaching Earth causing more disease (skin cancers and cataracts) and damage to vegetation. Because of the the depletion of the ozone layer, countries started to ban the use and production of CFCs. USA and Norway were the first to ban in 1978 and then in 1985 the Montreal Protocol (now signed by 160 countries) severely limited the production of CFCs. After 1996 only recycled CFCs could be used. Since the banning of CFCs the rate of depletion is believed to have slowed.
Sidoarjo is on the island of Java in Indonesia, 20km south of Surabaya. Indonesia sits on a destructive plate boundary (the Indo-Australian plate is subducting under the Eurasian plate). As well as earthquakes and volcanoes being present at destructive plate boundaries, mud volcanoes are also common, especially in East Java.
East Java has also got large oil and gas reserves. In order to try and access these reserves PT Lapindo Brantas had started exploratory drilling. On the 28th May PT Lapindo Brantas drilled two boreholes. The second borehole was deeper reaching a depth of 2,834 metres. However, the drill used for this borehole did not have a protective casing which allowed water, steam and a small amount of gas to be released triggering an explosion. The first explosion was about 200 metres from the drill sites, further explosions on the 2nd and 3rd June happened 800-1000 metres from the drill site.
The explosions caused fractures to the surface and by 5th June locals noticed mud escaping. In the first three months the daily flow of mud was between 7,000 and 150,000 cubic metres. 240 hectares of rice paddies were lost, along with eight villages and 25 factories. In total 11,000 people were displaced. On the 23rd December ground subsidence caused a gas leak and explosion killing 11. 18 months after the initial explosions 20km2 of land had been lost, 11 towns buried, 16,000 displaced, the local railways line had been covered along with the Porong-Gempol toll road.
Dams and barriers were created to try and contain the flow, concrete balls were dropped into the fractures and mud pumped into the Porong River and Java Sea. Despite efforts to stop the flow, scientists have estimated that the flow could continue for up to 40 years.
The company involved initially blamed an earthquake for the accident. However, courts have already ordered the company to pay $400 million in clean up costs and compensation. The fear is that with clean-up costs like to exceed $1 billion, PT Lapindo Brantis will just declare bankruptcy.