Maybe just make the handprint globes! These Earth Day "Handprint Globes" glued on black construction paper, along with students' creative writing assignments would make a visually stunning Earth Day bulletin board display.
Week Geography: Make Pumpkin Globes! - Tape down the continents and paint the pumpkin blue. The next day, remove the continents and color them in green with marker. Put two rubber bands around the pumpkin to represent the equator and voila, Pumpkin Globe!