Subject: Geography | Level: GCSE | Exam Board: OCR
This study guide for OCR GCSE Geography delves into the critical topic of Climate Change, equipping candidates with the precise knowledge and skills to excel in their exams. It unpacks the distinction between natural and anthropogenic climate drivers, evaluates evidence, and assesses management strategies, making a complex global issue clear and accessible.
Revision Notes & Key Concepts
Key Terms & Definitions
- Quaternary Period
- The most recent geological period, covering the last 2.6 million years, characterised by a series of glacial and interglacial periods.
- Anthropogenic
- Originating from human activity.
- Mitigation
- Action taken to reduce or prevent the causes of a problem. In climate change, this means reducing greenhouse gas emissions.
- Adaptation
- Action taken to adjust to the impacts of a problem. In climate change, this means managing the effects of rising temperatures and sea levels.
- Albedo Effect
- The reflectivity of a surface. Light-coloured surfaces like ice have a high albedo and reflect solar radiation, while dark surfaces like oceans or rock have a low albedo and absorb it.
- Thermal Expansion
- The tendency of matter to expand in volume in response to an increase in temperature.
Worked Examples
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Worked Example
Question: Explain the natural causes of climate change. (8 marks)
Solution: **Introduction**: The Earth's climate has always fluctuated naturally over geological time, long before human influence. These changes are driven by several natural forcing mechanisms, primarily Milankovitch cycles, solar variation, and volcanic activity. **Paragraph 1 - Milankovitch Cycles**: One key set of causes are the Milankovitch cycles, which alter the amount of solar radiation reaching the Earth. The first is eccentricity, where the Earth's orbit changes from circular to elliptical over a 100,000-year period, affecting the length and intensity of seasons. The second is obliquity, a 41,000-year cycle where the Earth's axial tilt varies between 22.1° and 24.5°, influencing the severity of seasons. Finally, precession is a 26,000-year wobble on the Earth's axis, which changes the timing of the seasons. **Paragraph 2 - Solar Variation and Volcanism**: Another natural cause is variation in the sun's output. The sun has cycles of activity, such as the 11-year sunspot cycle, where higher activity leads to slightly more energy reaching Earth, causing minor warming. Conversely, major volcanic eruptions can cause short-term cooling. For example, the eruption of Mount Pinatubo in 1991 ejected vast quantities of sulphur dioxide into the stratosphere, which reflected solar radiation and led to a global temperature drop of approximately 0.5°C for around two years. **Conclusion**: In conclusion, natural climate change is driven by a combination of long-term orbital cycles that dictate ice ages, and shorter-term factors like solar output and volcanic eruptions that cause temporary fluctuations.
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Worked Example
Question: Assess the effectiveness of mitigation strategies in tackling climate change. (12 marks)
Solution: **Introduction**: Mitigation strategies aim to tackle the root causes of climate change by reducing the concentration of greenhouse gases in the atmosphere. These include international agreements, switching to renewable energy, and afforestation. Their effectiveness can be assessed by their scale, cost, and level of implementation. **Paragraph 1 - International Agreements**: International agreements like the Paris Agreement (2015) are crucial for coordinating global action. The agreement's strength is its near-global consensus, with countries setting their own Nationally Determined Contributions (NDCs) to cut emissions. However, its effectiveness is limited because these NDCs are not legally binding, and there are no significant penalties for countries that fail to meet their targets. Furthermore, the withdrawal of major emitters like the USA (under the previous administration) can undermine its impact. **Paragraph 2 - Renewable Energy**: A key mitigation strategy is transitioning from fossil fuels to renewable energy sources like wind, solar, and hydroelectric power. This is highly effective at reducing CO2 emissions from the energy sector. For example, in the UK, renewables now account for over 40% of electricity generation. However, the effectiveness is limited by issues of intermittency (the sun doesn't always shine, the wind doesn't always blow), high initial investment costs, and the land area required for large-scale solar or wind farms. **Paragraph 3 - Afforestation & CCS**: Afforestation (planting trees) and Carbon Capture and Storage (CCS) are also important. Afforestation is a relatively low-cost method of creating a carbon sink. However, it requires vast areas of land and takes many years for trees to mature and absorb significant amounts of CO2. CCS involves capturing CO2 from industrial sources and storing it underground. While potentially very effective, the technology is extremely expensive and not yet proven at a large commercial scale, with very few operational projects worldwide. **Conclusion**: In conclusion, mitigation strategies have had some success, particularly the growth of renewable energy. However, their overall effectiveness is currently limited. International agreements lack enforcement, and technological solutions like CCS are not yet viable at the scale required. Therefore, while mitigation is essential, the current pace of implementation is not sufficient to prevent significant climate change, making adaptation equally critical.
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Worked Example
Question: For a named developing country, explain the impacts of climate change. (6 marks)
Solution: **Named Country**: Bangladesh. **Impact 1 - Flooding**: One major impact is increased flooding. As a low-lying delta country with 80% of its land less than 10m above sea level, Bangladesh is extremely vulnerable to both river and coastal flooding. Rising sea levels and more intense monsoon rains have exacerbated this. For example, in 1998, over two-thirds of the country was inundated, displacing 30 million people and destroying crops and infrastructure. **Impact 2 - Saltwater Intrusion**: A second impact, linked to sea-level rise, is saltwater intrusion. As the sea level rises, saline water pushes further inland into coastal river systems and groundwater. This contaminates drinking water sources, leading to health problems, and also makes agricultural land unusable for growing traditional rice crops, threatening food security and livelihoods for millions of farmers. **Impact 3 - Cyclones**: A third impact is the increasing intensity of tropical cyclones. Warmer sea surface temperatures in the Bay of Bengal provide more energy for storms, leading to stronger winds and heavier rainfall. Cyclone Sidr in 2007 was a devastating example, causing thousands of deaths and widespread destruction.
Practice Questions
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Question: Explain how human activities have caused the enhanced greenhouse effect. (6 marks)
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Question: Evaluate the reliability of different sources of evidence for climate change. (8 marks)
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Question: Describe two impacts of climate change on the UK. (4 marks)
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Question: To what extent are adaptation strategies more important than mitigation strategies in managing climate change for developing countries? (12 marks)
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Question: Explain how the albedo effect can create a positive feedback loop in the Arctic. (4 marks)
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