- "Airborn" (2004) and its sequels take place in an alternate history version of the 19th century, where airships are the primary mode of transportation.
- "Skybreaker" (2005) and its sequel are set in a post-apocalyptic future where the surface of the Earth has become inhospitable and humans live in floating cities.
- "Half Brother" (2010) is a contemporary novel that tells the story of two brothers, one of whom is a shapeshifter.
- "The Nest" (2015) is set in a near-future where genetically engineered creatures are used for various purposes, including as pets and in the entertainment industry.
As you can see, the time periods in Kenneth Oppel's books vary widely, so without specifying a particular book, it's not possible to provide a definitive answer to the question.