TOPIC: The Challenge of Natural Hazards Climate change section Slide 1: Evidence for climate change

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1 Slide 1: Evidence for climate change What is climate change? AQA definition: A long-term change in the earth's climate, normally associated with temperature change. The Earth is 4.5 billion years old. We have divided the history of the Earth into a number of periods. You need to know about the evidence we have for climate change from the quaternary period to the present day. What is the quaternary period? The period of geological time from about 2.6 million years ago to the present. It is characterized by the appearance and development of humans and includes the Pleistocene and Holocene Epochs. The Quaternary period is considered to be an ice age due to the ever present ice over Antarctica. In the last 100,000 years there have been glacial periods (colder temperatures on Earth) and interglacials (warmer temperatures on Earth) We are currently in the ice age but in a warmer part of it (interglacial.) Define climate change. (1mark)

2 Slide 2: Evidence for climate change Evidence that the climate has changed over the last 100 years: Since 1914 the Met Office has recorded reliable climate data using weather stations, satellites, weather balloons, radar etc. We therefore know that the Earth s surface temperature has increased by about 1 C in the last 100 years because we have measured it with thermometers. Sea levels have risen by 19cm since We know this because we have measured this. Evidence of climate changes a longer time ago: Extracting ice cores from Antarctica by drilling down and pulling out a column of ice. The deeper down the ice is from the older it will be because glacier ice builds up over time from layers of snow. We can measure the amount of greenhouse gases in air bubbles in the ice and work out how warm the Earth was at that time. Tree rings can also indicate past climate. In warmer years, tree rings are wider. Discuss the evidence for climate change. (6marks)

3 Slide 3: The natural causes of climate change Natural causes of climate change: 1. Solar output This is the amount of heat the sun gives out. This increases when more sunspots (dark patches) are observed on the sun s surface. This means the Earth will receive more heat. 2. Volcanic activity Volcanic eruptions can cause temporary climate change e.g. June 1991 eruption of Mount Pinatubo. The ash prevented the suns energy from entering the atmosphere and following the eruption, global temperatures dropped by 0.5 C. When this happens the cooler period is called a volcanic winter. Outline two natural causes of climate change. (4marks) Explain how climate change can occur due to natural factors. (4marks) Outline how volcanic activity can lead to climate change. (2marks)

4 Slide 4: The natural causes of climate change Milankovitch studied the Earths orbit (how the Earth goes around the sun) and found there were three cycles that affected the Earth s climate. 1. Eccentricity the Earth s orbit changes from circular to elliptical over 100,000 years. This appears to coincide closely with warmer and colder periods in the Earth s history. 2. Tilt The tilt of the Earth on its axis can change. When the angle of the tilt gets bigger we see colder winters and warmer summers. The cycle lasts 41,000 years. 3. Precession the Earth wobbles like a spinning top every 26,000 years. This leads to certain places in the world such as the far north experiencing long days and nights at certain times of the year. 4. See next slide for pictures showing the three orbital cycles. Explain how orbital cycles can lead to climate change. (2marks)

5 Cause 1: Orbital Changes (Milankovitch cycles) Complete cycle 100,000 years Complete cycle 41,000 years Complete cycle 26,000 years

6 Slide 6: Human causes of climate change What is the greenhouse effect? A naturally occurring phenomenon that keeps the Earth at the correct temperature for life to exist on Earth. Greenhouse gases in the atmosphere trap the suns heat which warms the planet. Some greenhouse gases are: Carbon dioxide, methane, water vapour. Without the greenhouse effect the Earth would be 33 C colder and it would be very difficult for any life to exist on Earth. What is the advanced greenhouse effect? Humans have increased the amount of greenhouse gases in the atmosphere which has trapped more heat and caused the Earth to heat up more than it would have done naturally. Human cause 1: Burning fossil fuels (coal, oil, natural gas) Account for over 50% global greenhouse gas emissions. Burning these releases carbon dioxide into the atmosphere. Fossil fuels are used in transportation, building, heating homes and in factories. They are also burnt in power stations to generate electricity. As population growth and wealth increases, the demand for power increases. Discuss how human activity can cause climate change. (6marks) Outline two ways in which humans can cause climate change (4marks)

7 Slide 7: Human causes of climate change Human cause 2: Agriculture Agriculture (farming) contributes 20% of greenhouse gas emissions. Large volumes of methane are produced by cattle during digestion. As population increases more food is required. As wealth increases there is a greater demand for expensive meat in people s diets. Human cause 3: Deforestation cutting down of trees. Forests are cut down to make space for agriculture, mining, roads and settlements and also for the logging industry (see living world rainforests powerpoint.) Which example could you talk about here? The Amazon rainforest in South America. Deforestation leaves less trees to absorb carbon dioxide through the process of photosynthesis. Trees are often burnt to clear the area for other uses. This burning releases carbon dioxide into the atmosphere. Climate change is natural and not caused by humans. To what extent do you agree with this view? (9marks)

8 Slide 8: The effects of climate change on people The effects of climate change are uncertain. The effects will vary and be uneven regionally and globally. The effects of climate change on people: Negative: Certain diseases will become more widespread. E.g. malaria. The fishing industry may be affected. People may no longer have enough food or be able to earn a living. This will affect their quality of life. Drought is likely to put pressure on food and water supplies in sub-saharan Africa. This may lead to famine and disease. Water shortages are likely to occur in countries such as the UK. Extreme weather is expected to increase. Flood risk will increase in the UK. Low lying nations such as the Maldives are at risk with sea level rise. Discuss how climate change may affect people and the environment. (6marks) Outline one effect of climate change on people. (2marks)

9 Slide 9: The effects of climate change on people Positive effects of climate change on people: Milder winters in countries such as the UK may lead to less deaths in the winter. Certain crops may grow more easily in different areas. We might be able to grow oranges and olives in the UK! The amount of crops we can grow might increase e.g. rice in Asia.

10 Slide 1: The effects of climate change on the environment. Negative effects of climate change on the environment: As ice retreats in the north, wildlife such as polar bears and seals may find it increasingly difficult to survive. As ice retreats in Antarctica (south) penguins may be affected. Coral reefs such as the Great Barrier reef in Australia may see a decline in biodiversity and warmer, more acidic oceans may cause coral bleaching. In the Amazon rainforest there may be high levels of extinction as parts of the rainforest turn to Savannah. Positive effects of climate change on the environment. Some species may find new habitats as ecosystems change. Outline one effect of climate change on the environment. (2marks) Suggest one positive impact of climate change. (2marks)

11 Slide 11: Managing climate change through mitigation Mitigation is trying to reduce the causes of the problem they try to reduce or prevent greenhouse gases being released into the atmosphere. 1. Alternative energy production. Renewable energy sources such as wind and solar power allow us to supply our energy needs without releasing gases into the atmosphere. Nuclear power is a non renewable source of power, coming from uranium, but also does not involve releasing greenhouse gases into the atmosphere. The UK aims to produce 15% of its energy by renewable sources by 2020 so its use is increasing. Problems: More expensive than fossil fuels. Many are reliant on the weather (solar or wind) and are therefore unreliable. Nuclear power comes with the risk of nuclear meltdown and power stations are expensive to build. Discuss how climate change can be managed through mitigation (6marks) Explain how alterative energy production can mitigate climate change. (2marks)

12 Slide 12: Managing climate change through mitigation 2. CCS: Carbon Capture and storage. This is when technology is used to capture the carbon dioxide produced by burning fossil fuels in factories and then pumped underground where it is stored. This is good because it means that the carbon dioxide is not released into the atmosphere and contributing to global warming. It is possible to capture 90% of carbon that would normally be released. This allows us to continue using fossil fuels to supply our energy in a less polluting way. Problems: The technology is new and requires further research and development before it can be used on a large scale. Carbon may leak back into the atmosphere. The money spent researching this could be better spent researching and improving renewable sources of energy which are more sustainable in the long term. Explain how CCS can mitigate climate change. (2marks) Evaluate CCS as a way of mitigating climate change. (4marks)

13 Slide 13: Managing climate change through mitigation 3. Planting trees. Trees act as carbon sinks, removing CO2 from the atmosphere through photosynthesis therefore the more trees we have, the less greenhouse gases in the atmosphere. Tree planting is well established in many parts of the world. China has used it to combat air pollution. In 2018, it assigned 60,000 soldiers the task of planting trees in the Beijing area. The UK has a 24.9million project in Brazil to restore areas of rainforest. Problems: If trees are planted, that stops the land being available for economic activities such as farming. Overall though tree planting is a very positive way of combatting climate change. Explain how planting trees can mitigate climate change. (2marks)

14 Slide 14: Managing climate change through mitigation 4. International Agreements. It is necessary for countries to work together as climate change is a global problem. There have been a series of international agreements, the most recent one being the Paris climate agreement in 2015 where 195 countries signed up to the deal to limit climate change. Problems: There has been criticism that these put in place aims and not firm commitments. Some countries, notably the USA refuse to sign up and have a significant amount of carbon emissions. Outline one way in which international agreements might mitigate climate change. (2marks)

15 Slide 15: Managing climate change through adaptation. What is adaptation? This is adjusting to the effects of climate change to cope better with the changes. These are local ways of managing the effects. 1. Change in agricultural systems: New irrigation systems in places where it wasn t needed before. Introducing drought resistant crop varieties, Educating farmers in water harvesting techniques. Trees can be planted to protect crops from strong sun. Planting dates can be changed. It will be much harder for poorer farmers in LICs to adapt than richer farmers in HICs. Suggest two ways in which we can adapt agricultural systems to help humans cope with climate change. (4marks)

16 Slide 16: Managing climate change through adaptation. 2. Managing water supply: Millions of people in Asia rely on meltwater from glaciers in the Himalayas for their water supply. This is threatened as glaciers shrink. One project that has been used is to dam water in in the winter which freezes. This then melts in the summer, supplying water when it is needed. In the UK London faces water shortages. Ways in which the UK can manage its water include: By reducing demand for water e.g. by fitting water saving devices to taps and showerheads. By increasing supply via a new desalination plant to remove salt from Thames water. This supplies drinking water for 400,000 homes. The problem with this is that it is very expensive. It is possible to adapt to climate change. To what extent do you agree with this statement? (9marks)

17 Slide 17: Managing climate change through adaptation. 3. Reducing risk from rising sea levels. Average sea levels have risen by 19cm since This happens due to increased melting of glaciers on land and thermal expansion of the oceans. (Water expands when it gets warmer) It is expected to rise a further 26-82cm by This will flood important agricultural land in Bangladesh and India. The Maldives are a group of low lying islands in the Indian Ocean. The highest point is 2.4m above sea level. Some things being done on the Maldives include: Relocation of the population to Sri Lanka. Construction of sea walls this is happening around the capital, Male. Building houses on stilts Explain how we can adapt to the problem of rising sea levels. (4marks)

18 Slide 18: Quiz How long ago did the quaternary period start? 2.6million years ago. What year did the Met Office start recording climate data? 1914 How much have sea levels risen since 1900? 19cm How much have global temperatures risen in the last 100 years? 1 degree C. How much has Arctic sea ice thinned by since 1970? 65% When did Mount Pinatubo last erupt? How much did global temperatures drop after this eruption? 0.5 degrees C. What % global greenhouse gas emissions comes from a) burning fossil fuels and b) agriculture? A) 50% b) 20%

19 Slide 19: Quiz Name 2 animals at risk from climate change. Polar bears, penguins How much of our energy are we aiming to get from renewable sources by 2020? 15% CCS can lock away what % of carbon that would otherwise be released into the atmosphere by burning fossil fuels? 90% How many soldiers planted trees in China in 2018? 60,000 Name the last international global climate agreement. The 2015 Paris Climate agreement How high are the Maldives above sea level? 2.4m is the maximum height. What is the capital of the Maldives? Male