# 2 Different possible futures

Human activities are the dominant influence on current climate change. But how can scientists predict what future greenhouse gas emissions will be?

## Activity 2 Human-caused factors

Allow approximately 5 minutes

Take five minutes to note down what human-caused factors you think will influence future greenhouse gas emissions.

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### Discussion

Discussion: Future greenhouse gas emissions will depend on factors such as:

- global population and wealth
- political decisions, like the regulation of industrial sources
- how much energy we will use, and from which sources
- new technologies not yet imagined
- how we’ll make food and use the land.

Scientists and other experts do have some idea about the likely bounds of future population, wealth, politics, technology, agriculture and culture, but these factors are impossible to predict exactly: and there are often big surprises, such as new inventions. This means it is impossible to predict future greenhouse emissions exactly.

So, scientists make predictions of climate change for a set of different ‘possible futures’. This means that rather than trying to predict how the climate will change, scientists try to predict how the climate would change if human activities changed in a particular way – in other words, they are ‘what-if’ scenarios. These scenarios are designed to span the likely bounds of what could happen, even if no individual scenario comes to pass exactly.

OpenLearn - Could we control our climate?
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