LitCharts assigns a color and icon to each theme in The 5th Wave, which you can use to track the themes throughout the work.
Trust and Belief
Survival and Perseverance
Warfare and Dehumanization
Family
Summary
Analysis
When Cassie, Ben, and Sammy make it past the debris to the surface, they emerge on a barren landscape where the sky is full of drones. A cargo plane is about to take off, and though it’s difficult to communicate over the noise, Ben and Cassie make a plan and start running.
The barren landscape with a sky full of drones is a visual sign of all the devastation that the aliens have brought to Earth. Ben and Cassie’s difficulty talking over the noise also echoes how the aliens tried to tear humanity apart by stopping communication.