The evidence for climate change in the Quaternary period; the natural causes (orbital cycles, sunspots, volcanic activity) and the human enhanced greenhouse effect; the impacts of climate change; and how it can be managed through mitigation and adaptation.

What this dot point is asking

This is OCR GCSE Geography B (J384) Component 1, Our Natural World, the Changing Climate topic: "Is climate change cause for concern?" OCR expects you to describe the evidence for climate change in the Quaternary period, explain its natural causes (orbital cycles, sunspots, volcanic activity) and the human enhanced greenhouse effect, describe its impacts on people and the environment, and explain how it can be managed through mitigation and adaptation.

Evidence from the Quaternary period

The Quaternary is the most recent geological period, the last roughly 2.6 million years, during which the global climate has repeatedly swung between cold glacial periods (ice ages) and warm interglacial periods. Geographers reconstruct these changes from several sources.

Natural and human causes

Climate has always changed naturally, but the present rapid warming is driven by people.

Natural causes:

• Orbital (Milankovitch) cycles. Slow, regular changes in the Earth's orbit alter how much solar energy reaches the surface and where: the eccentricity (shape) of the orbit, the axial tilt, and the precession (wobble) of the axis. These cycles drive the long glacial and interglacial swings of the Quaternary.
• Sunspot activity. The Sun's output varies slightly over cycles of about 11 years and longer; more sunspots mean a slightly more energetic Sun and a warmer climate.
• Volcanic activity. Large eruptions inject ash and sulphur dioxide high into the atmosphere, where they reflect sunlight and cause short-term cooling.

Human cause: the enhanced greenhouse effect.

Impacts of climate change

Impacts are environmental, economic and social.

• Environmental. Melting ice sheets and glaciers, rising sea levels, warming and acidifying oceans, shifting ecosystems and more frequent extreme weather (heatwaves, droughts, intense storms).
• Economic. Damage from flooding and storms, falling crop yields in some regions, and the cost of defences and adaptation.
• Social. Threats to water and food supplies, displacement of people from low-lying coasts and small islands, and health impacts from heat and disease.

The impacts fall unevenly: many of the poorest countries, least able to cope, are among the worst affected.

Managing climate change: mitigation and adaptation

There are two broad strategies, and OCR expects you to compare them.

• Mitigation reduces the causes. It includes switching to renewable energy (wind, solar, hydro), afforestation (planting trees to absorb carbon dioxide), carbon capture and storage, energy efficiency, and international agreements such as the Paris Agreement that commit countries to cut emissions.
• Adaptation helps people cope with the effects already happening. It includes flood defences and sea walls, drought-resistant crops, changes to water management, and redesigning buildings and farming for a warmer climate.

Mitigation tackles the root problem but is slow and needs global cooperation; adaptation protects people now but does not stop warming. Most experts argue that both are needed together.

Try this

Q1. Describe the difference between a glacial and an interglacial period. [2 marks]

• Cue. A glacial is a cold period with ice advancing; an interglacial is a warmer period between glacials.

Q2. Suggest one mitigation and one adaptation strategy for a low-lying coastal country. [4 marks]

• Cue. Mitigation: invest in renewable energy to cut emissions. Adaptation: build sea walls and flood defences to cope with rising sea levels.