7. Artificial treesOne of the many reasons deforestation is bad: Trees naturally scrub atmosphere-warming carbon dioxide from the atmosphere. Scientists at Columbia University are developing plastic trees that can pull CO2 from the air–and so far, they do so 1,000 times more effectively than real ones. Of course, the world isn’t saved yet. Not only will the technology have to be developed further and refined, but there also will need to be a financial incentive for a company to deploy it. One possibility: Selling the stored carbon to manufacturers that can turn it into carbon nanofibers or plastics.