Topic 1: 1.3 Global climate is now changing as a result of human activity, and there is uncertainty about future climates — Edexcel GCSE Geography B
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Topic 1: 1.3 Global climate is now changing as a result of human activity, and there is uncertainty about future climates explained
Topic 1: 1.3 Global climate is now changing as a result of human activity, and there is uncertainty about future climates covers 3 specification points, including A.
Read the full explanation
How human activities (industry, transport,… and B. Evidence for how human activity is causing…. Open a point below for its explanation and revision guidance.
a. How human activities (industry, transport, energy, farming) produce greenhouse gases (carbon dioxide, methane) that cause the enhanced greenhouse effect leading to global warming.
This statement asks for a causal chain: human activities release greenhouse gases, which enhance the greenhouse effect and cause global warming. Industry and energy production, including burning coal, oil and gas, release carbon dioxide (CO₂). Transport adds CO₂ from petrol, diesel and jet fuel. Farming releases methane (CH₄) from livestock digestion and flooded rice paddies. Explain that these gases absorb and re-emit outgoing longwave radiation, so less heat escapes to space. This is the enhanced greenhouse effect, added to the natural effect that keeps Earth habitable. Finish by linking this to global warming, a rise in average global surface temperature.
b. Evidence for how human activity is causing climate change (sea level rise and warming oceans, global temperature rise, declining Arctic ice, increased extreme weather events) and the possible consequences on people.
This statement asks for evidence that human activity is causing climate change, plus the possible consequences for people. Sea level rise and warming oceans are measured by tide gauges, satellites and ocean temperature records. Global temperature rise appears in long weather station records. Declining Arctic ice is shown by satellite data. Increased extreme weather events, such as heatwaves and heavy rainfall, appear in observational records. Link each trend to human activity via rising greenhouse gas levels. For consequences, explain effects on people: coastal flooding, displacement, food and water insecurity and heat stress. Word these as possible outcomes, not certainties.
c. The range of projections for global temperature change and sea level rise in the future, including physical processes and reasons for uncertainty about those projections.
Projections estimate future global temperature rise and sea level rise, usually as a range, because climate models are run under different emission scenarios. Warming drives sea level rise through thermal expansion of seawater and through meltwater from glaciers and ice sheets. Feedbacks, such as loss of reflective sea ice (albedo change) and carbon release from thawing permafrost, can amplify warming. Uncertainty arises from unknown future emissions, incomplete understanding of ice sheet response, limits in model resolution and natural variability in the climate system. A strong answer names a physical process, links it to the projected range and explains why values differ.
Your focus
- Identify at least four human activities that release greenhouse gases.
- Select the correct greenhouse gas for a given human activity in a multiple-choice question.
- Explain in one sentence how the enhanced greenhouse effect leads to global warming.
Show all 9 objectives
- Identify four pieces of evidence for human-caused climate change from a list.
- Select the correct measured trend described in a multiple-choice question stem.
- Explain one possible consequence of climate change for people in a single sentence.
- Describe the range of projections for future global temperature and sea level change.
- Explain the physical processes that drive projected sea level rise.
- Explain the reasons why future climate projections are uncertain.
Topic 1: 1.3 Global climate is now changing as a result of human activity, and there is uncertainty about future climates exam tips
Marking Points
- Identifies industry and energy production as sources of carbon dioxide from burning fossil fuels.
- Identifies transport as a source of carbon dioxide from petrol, diesel and jet fuel.
- Identifies farming as a source of methane, for example from livestock digestion or rice paddies.
- Explains that greenhouse gases absorb and re-emit outgoing longwave radiation, so more heat is retained.
- Links the enhanced greenhouse effect to a rise in average global surface temperature, or global warming.
- Cites measured sea level rise and ocean warming, using tide gauge or satellite evidence.
- Cites rising global temperature using weather station or ocean records.
- Describes declining Arctic sea ice using satellite data on its shrinking extent.
- Describes increased extreme weather events, such as heatwaves or heavy rainfall, as observed trends.
- Links the evidence to human activity through rising greenhouse gas concentrations.
- Explains a possible consequence for people, such as coastal flooding, food insecurity or heat stress.
- Gives a projected range for global temperature change or sea level rise rather than a single fixed value.
- Explains thermal expansion as a physical process that raises sea level as seawater warms.
- Links melting glaciers and ice sheets to meltwater entering the oceans and raising sea level.
- Identifies at least one feedback, such as albedo change from melting sea ice, and explains how it amplifies warming.
- Explains at least two reasons for uncertainty, such as unknown future emissions or incomplete understanding of ice sheet behaviour.
Examiner Tips
- 💡Read every option, then eliminate any that name a gas or source not linked to the statement's list of activities.
- 💡Check that the chosen option follows the full chain: source, then gas, then heat trapping, then warming.
- 💡When two options look similar, choose the one that pairs the correct gas with the correct source, such as methane from livestock rather than carbon dioxide from livestock.
- 💡Match each option to one of the four named trends, and check any option that describes a trend not on the list.
- 💡Look for words such as possible or likely in options about the future; certainty wording is often the wrong choice.
- 💡Prefer options that name a measured trend and its evidence source, such as satellite data, over vague general statements.
- 💡Name the emission scenario or model basis when describing a range, because the range reflects different assumptions about the future.
- 💡Attach a unit to every value, for example °C for temperature and metres or centimetres for sea level.
- 💡Write a two-step chain for each process: the process itself, then its effect on the projected value.
Common Mistakes
- Confuses the natural greenhouse effect with the enhanced greenhouse effect; state that human emissions strengthen the natural process.
- Lists sulphur dioxide as a greenhouse gas; correct this by describing it as an aerosol with a cooling effect rather than a heat-trapping gas.
- Attributes all emissions to cars; name industry, energy, farming and transport together as separate sources.
- Treats the ozone layer as the cause of global warming; identify carbon dioxide and methane as the gases that trap heat.
- Offers a personal opinion about climate change instead of cited, measured trends; use data-based evidence.
- Describes evidence without linking it to human activity; add the greenhouse gas link.
- Presents future consequences as certain; use possible or likely wording for predicted outcomes.
- Treats a single hot summer as proof of global warming; cite long-term trends from records instead.
- Ignores consequences for people and lists only physical changes; add a human impact for each trend.
- Treats projections as certain forecasts; state that they are estimates with a range of possible outcomes.
- Claims sea level rise comes only from melting ice; include thermal expansion of seawater as a separate process.
- Describes uncertainty as simply poor data; explain specific physical or scenario-based reasons for it.
- Lists physical processes without linking them to the projected change; explain how each process affects the outcome.