The standard strategy is to designate protected areas in remote regions where the cost and the inconvenience to humans is minimal. Australia, for instance, has largely put protected areas in its vast central desert region, rather than in coastal areas where they would protect more threatened species — but also inconvenience more people. Likewise, Brazil in March designated new marine protected areas the size of France and the United Kingdom combined, but omitted near-shore areas where there’s a greater diversity of wildlife facing more immediate threats from human activity.

Writing about the Half-Earth Project, a bid by conservationists to keep half the planet “as wild and protected from human intervention or activity as possible,” E. O. Wilson cautioned that making decisions about which habitats to protect without a more complete knowledge of Earth’s existing species “would lead to irreversible mistakes.” But the authors of the Nature Ecology and Evolution study put it more tersely: Pretending to protect species based purely on the number of acres protected is like managing human health care based on the number of hospital beds, “irrespective of the presence of trained medical staff” or “whether patients live or die.”

Researchers who looked at the home ranges of more than 4,000 threatened birds, mammals and amphibians worldwide for a 2014 study found that protected areas miss 85 percent of them. Even if all 168 convention signatories meet their 2020 protected area targets, their acreage monomania means they’d still miss 84 percent of threatened species, says Oscar Venter, a conservation scientist at the University of Northern British Columbia and the lead author of that study. Is it any wonder, then, that species and subspecies continue to go extinct — the western black rhino in 2011, the Japanese river otter in 2012, the Formosan clouded leopard in 2013, the Bramble Cay melomys in 2016 — even as we celebrate our success stories?

“If we are going to take natural history seriously, and all the things our communities and our economies depend on from natural areas,” Mr. Venter said, “we have to start putting parks in the right places and managing them in the right way.” That will at times entail setting aside our profits and our precious convenience, and it may seem like a stretch to imagine our self-indulgent species ever acting on this reality. But the alternative is to spend our lives in a world increasingly without wildlife.