Leading scientists and conservationists are proposing that up to 50 percent of the earth’s land and oceans be protected in the coming decades. While some view the goal as unrealistic, proponents say it is essential for preserving the natural systems on which life itself depends.

As humans continue to rapidly expand the scope of their domination of nature — bulldozing and burning down forests and other natural areas, wiping out species, and breaking down ecosystem functions — a growing number of influential scientists and conservationists think protecting half of the planet in some form is key to keeping it habitable.

The idea first received public attention in 2016 when E.O. Wilson, the legendary 90-year-old conservation biologist, published the idea in his book Half Earth: Our Planet’s Fight for Life. “We now have enough measurements of extinction rates and the likely rate in the future to know that it is approaching a thousand times the baseline of what existed before humanity came along,” he told The New York Times in a 2016 interview.