April 22 marks Earth Day, and this year's theme is "Planet vs. Plastics". Over the past 60 years, around 7 billion tons of plastic have been produced, according to the UN. But only around 10 percent of it has been recycled. Initiatives are flourishing around the world to tackle the waste crisis, including new technology to improve recycling rates. French startup Carbios has developed an alternative method to mechanical recycling, using plastic-chewing enzymes to break down polyethylene, one of the most common single-use plastics in the world. The Down to Earth team visited their demonstration plant in Clermont-Ferrand.