True confession...I google!
I googled 'undergraduate environmental topics'.
Example
I stumbled across this article which got me interested in how eating meat can affect the environment.
I ended up at this research question: How does eating meat impact global warming?
Step 1: Break up this research question into two or three main concepts.
Step 2: Brainstorm synonyms, acronyms, and variant spellings.
Even if the search engine you are using doesn't require you to enter boolean operators, it is still using them behind the scenes. It will help you to know the logic behind your search.
For example, you might search:
(meat OR livestock) AND (impact OR effect) AND ("global warming" OR climate)