These global warming hourglasses by Ferdi Rizkiyanto feature tiny worlds to indicate the precious resources we must preserve. There's the metropolis, with birds soaring among the skyscrapers, a series of tree stumps, traffic-clogged streets, and a gas station. Above that, there's a series of melting glaciers, with a penguin and a polar bear each stranded on their own iceberg.

Ferdi Rizkiyanto's global warming hourglasses shed light on our current practices. Check out some other insightful global warming awareness designs below.