Climate Change overview for N(A)-Level Geography (SEAB 2246): the natural and human causes, the evidence that the climate is warming, the impacts on people and the environment, and how people respond through mitigation and adaptation

What this topic demands

Climate Change is the theme where physical processes and human choices meet. In the N(A)-Level Geography syllabus (SEAB 2246), the marks come from explaining the cause clearly (especially the enhanced greenhouse effect), quoting solid evidence, organising impacts on both people and the environment, and separating the two kinds of response: mitigation and adaptation. Keep cause, evidence, impact and response as four distinct boxes and you will rarely go wrong.

This guide ties together the matching dot-point pages, each with its own practice. See the full set at /sg-n-level/geography/syllabus and the subject hub at /sg-n-level/geography.

The causes of climate change

The causes of climate change are both natural and human. Natural causes include changes in the Sun's output, large volcanic eruptions and slow shifts in the Earth's orbit. The dominant cause of today's rapid warming, however, is human activity through the enhanced greenhouse effect. The natural greenhouse effect keeps the Earth warm enough to live on by trapping some outgoing heat. By burning fossil fuels (coal, oil and gas) and clearing forests, humans release extra greenhouse gases such as carbon dioxide and methane, which trap more heat and warm the planet beyond its natural level.

The evidence for climate change

The evidence for climate change is the part where you must quote measurable trends, not feelings. The strongest lines are: rising global average temperatures measured over many decades, shrinking glaciers and ice sheets and melting sea ice, rising sea levels as warmer water expands and land ice melts, and biological signs such as earlier flowering and species shifting toward cooler areas. Scientists are confident because these independent lines of evidence, collected worldwide by many separate teams, all point the same way.

The impacts of climate change

The impacts of climate change fall on both people and the environment. Sea-level rise threatens low-lying coasts and islands (a direct concern for Singapore) with flooding and loss of land. More extreme weather, such as stronger storms, heatwaves, droughts and heavy rain, harms homes, health and farming. Food and water supplies are stressed as harvests fail and water becomes scarce in some regions. Ecosystems suffer too, with coral bleaching and habitats lost as conditions change faster than species can adapt. Always separate the human impacts from the environmental ones.

Responding to climate change

People respond in two distinct ways, and you must keep them apart. Responding to climate change through mitigation tackles the cause by cutting emissions: switching to renewable energy (solar, wind, hydro), improving energy efficiency, and protecting and planting forests that absorb carbon dioxide. Adaptation copes with effects that are already happening: building coastal defences, raising land, growing drought-resistant crops and improving flood warnings. Action happens at every level, from international agreements to national policy and individual choices.

Worked example: reading a temperature trend

Check your knowledge

Attempt these under timed conditions, then check the matching dot-point pages.

1. Explain how the enhanced greenhouse effect warms the planet. (3 marks)
2. State three lines of evidence that the climate is warming. (3 marks)
3. Describe two impacts of climate change on people. (2 marks)
4. Explain the difference between mitigation and adaptation, with one example of each. (3 marks)
5. Explain why Singapore is especially at risk from climate change. (3 marks)
6. Suggest two ways individuals can help reduce greenhouse gas emissions. (2 marks)