82-year-old retired geochemist from the Netherlands - Olaf Schuiling, proposes that olivine offers a solution to global warming. The green-tinted rock is mineral that is believed to be a major constituent of Earth’s upper mantle and, when exposed to open air, removes carbon dioxide from our atmosphere. Schuiling suggests the rock is used for footpaths, roads and even as the base of children’s playgrounds, as has been implemented in the Netherlands. Using enough olivine, he says, can remove enough CO2  to significantly slow rising temperatures across the world.

Image: A playground surface made of olivine in Arnhem, the Netherlands. Source: Jasper Juinen for The New York Times