Humankind has reached a notable milestone this week, though it’s not one to celebrate. For the first time in history, human-made materials now outweigh all life on Earth, meaning that humanity’s footprint is actually heavier than that of the entire natural world. According to a new study in Nature, the weight of human-made buildings, roads, and other manufactured materials currently weighs 1.1 trillion tons, and doubles about every 20 years.

The study showed that at the start of the 20th century, the mass of human-produced objects was equivalent to only three percent of the weight of Earth’s total biomass. Since the post-World War II production boom, however, the manufacturing increase has been immense, rapidly increasing the mass of human-made materials.

Ron Milo of Israel’s Weizmann Institute of Science, and one of the study’s co-authors, said, “This study provides a sort of ‘big picture’ snapshot of the planet in 2020. We hope that once we have these somewhat shocking figures before our eyes, we can as a species take responsibility.”

If the growth rate continues at the current pace, human-made materials are on track to weigh as much as three trillion tons by 2040. This is particularly troubling because natural biomass is declining.

Emily Elacham, the study’s lead author, told AFP that humanity “can no longer deny our central role in the natural world. We are already a major player and with that comes a shared responsibility.”