BTW: What problems have you identified that google.com has, and what are your suggested solutions?
2. It sounds like you have to decide if you want to make money or solve problems you deem worthy of solving. If it's the latter, make money first. Funds allow you to work on passion projects, even hire a team. Passion projects are not much fun if you worry about paying bills.
3. Problems like global warming is something you won't solve on your own, but a single person can still create valuable contributions. It's not abstract. Simply work on anything that reduces/captures emissions, anything reducing energy use, or technology that replaces that which is heavy on emission.