If the question asks you to explain a problem related to the environment, you could write about global warming.
Here is a paragraph explaining the problem (causes) of global warming:
Perhaps the most serious problem facing the environment is global warming. Gases such as carbon dioxide trap heat from the sun within the earth’s atmosphere, and this causes global temperatures to rise. This process is known as the greenhouse effect, and human activity is a major factor in the rise of the greenhouse gases which cause it. For example, factories and vehicles produce emissions and exhaust fumes. As many developing countries are becoming industrialised, emissions from factories are expected to increase. Furthermore, the number of cars on our streets is growing all the time, and cheap air travel is making flying accessible to more and more people. Consequently, the amount of greenhouse gases released into the atmosphere shows no signs of decreasing.
You can learn a lot from this paragraph if you analyse it:
- How many sentences are there? What does each sentence do? (e.g. The first sentence introduces the topic)
- Can you find some "band 7 vocabulary"?
- Look at how the ideas are linked. Can you see that the word "this" is an important linking word?