It’s Earth Day—take a walk with us. First, let’s dig into issues taking root in Search. Ahead of Earth Day, “solar energy,” “drought” and “endangered species” climbed in popularity this week. Meanwhile, people are looking for ways their own actions can make a positive impact. The top “how to recycle” searches were for plastic, paper, batteries, plastic bags, and styrofoam. And around the world, trending queries about Earth Day were “how many trees will be saved by recycling?” and “which…