Ecosia is one of those "green" solutions that you can implement pretty seamlessly. Just set it up as your browser's default search engine and everything will work about the same as before, but the revenue from ads in the search results will go toward planting trees around the world. They're very transparent about their finances and often post videos about how the planting is going.

The search results you're getting are coming from Bing, so if you're used to using Google, that'll be a change. Also, if you're using an ad blocker, you'll need to turn that off for Ecosia's domain in order to actually see the ads; otherwise, you're not actually generating any tree-planting money. I do admit I have occasionally explicitly searched for something with Google because I wasn't getting the results I expected, but that has become less common over time.

They also have a browser app for smartphones.

If you're unhappy with Ecosia's search results but otherwise like this idea, Ekoru is an alternative that funds planting seagrass, but I haven't vetted them at all.