Human-made materials now equal weight of all life on Earth

ENVIRONMENTALISTS OFTEN SAY that humanity needs to shrink its planetary footprint. Now, a new study has demonstrated how literally massive that footprint is.

While the mass of Earth’s life forms stands at about 1.1 trillion metric tons (1.2 trillion U.S. tons) and has not changed much in recent years, the so-called “anthropogenic mass” of artificial materials is growing exponentially. The mass of everything people have built and made, from concrete pavements and glass-and-metal skyscrapers to plastic bottles, clothes, and computers, is now roughly equal to the mass of living things...