In 2016, an international team of scientists set out to determine how much of the earth’s land is still wild. They were alarmed at what they found: Deserts, grasslands, tropical and boreal forests are all rapidly disappearing. In the last two decades, 10 percent of terrestrial wilderness has been replaced by buildings, farmland, and other development. Only 23 percent of all land on the planet remains relatively untouched.

The ocean is in an even more dire state. In a study published this summer, a research team made up of some of the same scientists found that only 13 percent of the ocean can be classified as marine wilderness. The rest has been altered by anthropogenic stressors, such as industrial fishing, pollution, and shipping.

The ocean research was limited by a lack of historical data, so it’s unknown how quickly marine wilderness has declined in the last 20 years. But the two papers make one thing clear: Humans are threatening a complete takeover of both the land and the sea. After climate change, it’s the most urgent environmental crisis of our time.

On Wednesday, the scientists led by Australia’s University of Queensland attempted to explain why the impending disappearance of wild places is so dire. “Numerous studies are starting to reveal that Earth’s most intact ecosystems have all sorts of functions that are becoming increasingly crucial,” they wrote in the prestigious journal Nature.

The general public may view wilderness areas like recreational facilities. But scientists see them more like libraries. They contain a wealth of information about the natural world—why it has thrived for so long, how it adapts and evolves under the pressure of evolution, and what truly makes it die. They are “important reservoirs of genetic information, and act as reference areas for efforts to re-wild degraded land and seascapes,” the scientists wrote. The information contained in wild places allows researchers to predict what will happen as climate change worsens.