Answer:
How are they different to 'greenhouse gases'? Greenhouse gases are naturally occurring. They include carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). Synthetic greenhouse gases are man made chemicals and generally have a much higher global warming potential than naturally occurring greenhouse gases.
Explanation:
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In geography a human settlement is a locality or populated place is a community in which people live.
Answer to number 1. watershed
number 2. point 3
number 3. non point