Rearrange the following sentences to form a coherent paragraph:

1. One effective approach is to broaden energy options by moving away from fossil fuels towards renewables such as solar, wind, and geothermal energy.

2. To reduce the severe impacts of climate change, nations must sharply cut dependence on high-carbon energy generation.

3. This transition not only lowers greenhouse gas output but also improves air quality and opens up new economic possibilities.

4. In addition, measures that encourage energy efficiency in buildings and transport can further reduce total energy use.

The correct order of sentences to form a coherent paragraph is 2, 1, 3, 4.

Step-by-step Logical Breakdown:

1. Identify the Topic Sentence (Introductory Statement):
Sentence 2 ("To reduce the severe impacts of climate change, nations must sharply cut dependence on high-carbon energy generation.") introduces the overarching theme of the paragraph: the need to reduce climate change impacts by cutting high-carbon energy dependence. Therefore, sentence 2 serves as the ideal opening statement.

2. Follow with the Solution/Approach:
Sentence 1 ("One effective approach is to broaden energy options by moving away from fossil fuels towards renewables such as solar, wind, and geothermal energy.") provides a direct method to address the requirement mentioned in sentence 2. It introduces renewable energy as an alternative approach.

3. Elaborate on the Benefits of the Solution:
Sentence 3 ("This transition not only lowers greenhouse gas output but also improves air quality and opens up new economic possibilities.") starts with the demonstrative phrase "This transition", which directly points to the shift towards renewables described in sentence 1. Thus, sentence 3 logically follows sentence 1.

4. Add Supplementary Information/Measures:
Sentence 4 ("In addition, measures that encourage energy efficiency in buildings and transport can further reduce total energy use.") adds an additional strategy to further mitigate energy use. The transition phrase "In addition" makes it a natural concluding point for the paragraph.

Conclusion:
Arranging the sentences in the sequence 2 → 1 → 3 → 4 forms a logical flow from problem/goal → primary solution → benefits of solution → additional complementary measures.