Crossword clues for the word: ECOLOGIST The word ECOLOGIST has appeared as an answer to at least 5 crossword clues on different crossword puzzles. Crossword clues for ECOLOGIST Showing 1 to 5 of 5 results Clue(s) "Global warming researcher, often" Environmental expert first to pursue on-line carbon monoxide register EPA scientist One concerned with invasive species Student of environments.