I think it would be a good idea to do some research on 'hot topics' such as energy conservation etc.
You don't need to do any research on the hot topics such as energy conservation etc. Actually you don't need understanding of any subject or topics for GMAT AWA.
If you go through OG AWA section, you'll find a large number of AWA topics, that would give you some idea on what kindda topic you'll be facing in GMAT. Also, you can try searching for sample answers, just type in one sentence (in quotes " ") from the list of OG AWA topics in google, and you would be amazed by the search results.
All the best.
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