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Unlock This CourseAn increase in average global temperature is a major cause of climate change. A change of a degree or two in the average sounds small. But it affects the whole planet, because the weather, the oceans and living things are all linked.
Scientists use models to predict what might happen. Nobody can be completely certain, so we talk about potential effects. Here are four of them.
Melting glaciers add water to the sea, and warmer water expands too, so sea levels rise
Warmer weather melts ice on land, such as glaciers. The extra water runs into the sea. Water also takes up more space as it warms. Higher seas can flood low-lying coasts and damage homes, farmland and fresh water supplies. Coasts can also be worn away faster (coastal erosion).
Some places could get more frequent or more severe storms, heatwaves, floods and droughts. These put lives, buildings and power supplies at risk.
The amount and the pattern of rainfall may change. Some areas could get much more rain and others much less. This changes where there is enough water to drink and to grow crops.
Many species are suited to a small range of temperatures. They may have to move to new places, or may die out if they cannot. Changes in temperature and rain also change which crops can be grown and how much food farms can make.
The spec asks you to discuss these effects. That means weighing up three things:
The effects can also link together. Less rain can mean poorer harvests. Poorer harvests can mean less food. Floods can ruin farmland. A good answer shows these links and says that the exact size of each effect is uncertain.
Do not say climate change is "the hole in the ozone layer". That is a different problem. Do not say that the whole world simply gets hotter everywhere: some places may get wetter, drier or stormier instead. Use the word potential, because these are predictions.
Key terms:
The words "full life cycle" matter. The footprint of a pair of trainers is not just the emissions from the factory. It includes getting or growing the raw materials, making the parts, moving them by lorry and ship, the energy used to sell them, and what happens when they are thrown away.
A footprint can also belong to a service (such as a bus journey) or an event (such as a music festival). Each one has its own total, found by adding up every stage.
Solar panels on a roof cut the carbon footprint by swapping fossil-fuel power for renewable energy
The carbon footprint can be reduced by reducing emissions of carbon dioxide and methane. Here are some actions.
If these actions are so good, why have emissions not stopped? The spec asks you to give reasons why actions may be limited.
A festival has a carbon footprint. Stages that add to it: the fuel in the lorries carrying equipment, the electricity from diesel generators, and the travel of the visitors. To reduce it, the organisers could power the stages with solar panels and offer a coach from the nearest town. Their action may be limited if the solar panels cost too much, or if visitors still choose to drive.
Describe two actions that could reduce the emissions of methane. Give one reason why these actions may be limited. (3 marks)
Farm fewer cattle (or change how rice is grown) so less methane is released. Collect methane from landfill sites and use it as a fuel instead of letting it escape. These actions may be limited because people may not want to change their diets, or because the changes cost a lot of money.
When a question says "give reasons why actions may be limited", write about cost, technology, lifestyle or countries failing to agree, and tie it to the action in the question.