“We will get woolly mammoths back.” So vowed environmentalist Stewart Brand at the TED conference in Long Beach, Calif., in February in laying out his vision for reviving extinct species. The mammoth isn't the only vanished creature Brand and other proponents of “de-extinction” want to resurrect. The passenger pigeon, Caribbean monk seal and great auk are among the other candidates—all species that blinked out at least in part because of Homo sapiens. “Humans have made a huge hole in nature in the last 10,000 years,” Brand asserted. “We have the ability now—and maybe the moral obligation—to repair some of the damage.”

Just a few years ago such de-extinction was the purview of science fiction. Now it is so near at hand that in March, Brand's Long Now Foundation, along with TED and the National Geographic Society, convened an entire conference on the topic. Indeed, thanks to recent advances in cloning and the sequencing of ancient DNA, among other feats of biotechnology, researchers may soon be able to re-create any number of species once thought to be gone for good.

That does not mean that they should, however. The idea of bringing back extinct species holds obvious gee-whiz appeal and a respite from a steady stream of grim news. Yet with limited intellectual bandwidth and financial resources to go around, de-extinction threatens to divert attention from the modern biodiversity crisis. According to a 2012 report from the International Union for Conservation of Nature, some 20,000 species are currently in grave danger of going extinct. Species today are vanishing in such great numbers—many from hunting and habitat destruction—that the trend has been called a sixth mass extinction, an event on par with such die-offs as the one that befell the dinosaurs (and much else) 65 million years ago. A program to restore extinct species poses a risk of selling the public on a false promise that technology alone can solve our ongoing environmental woes—an implicit assurance that if a species goes away, we can snap our fingers and bring it back.

Ironically, the de-extinction conference immediately followed the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) meeting in Bangkok, which underscored just how devastating the trade has been. Reports released to coincide with the meeting revealed that between 2002 and 2011, the African forest elephant population declined by 62 percent from poaching; that fishing kills at least 100 million sharks a year—many of them members of imperiled species; and that between 2000 and 2012, an average of 110 tigers a year were killed (as few as 3,200 of the cats remain in the wild). Poachers slaughter 30,000 African elephants every year for their ivory—the highest kill rate since the 1980s. At this rate, the species could disappear in two decades. So could Africa's rhinos, prized for their horns.

Already conservationists face difficult choices about which species and ecosystems to try to save, since they cannot hope to rescue them all. Many countries where poaching and trade in threatened species are rampant either do not want to give up the revenue or lack the wherewithal to enforce their own regulations. Against that backdrop, a costly and flamboyant project to resuscitate extinct flora and fauna in the name of conservation looks irresponsible: Should we resurrect the mammoth only to let elephants go under? Of course not.

That is not to say that the de-extinction enterprise lacks merit altogether. Aspects of it could conceivably help save endangered species. For example, extinct versions of genes could be reintroduced into species and subspecies that have lost a dangerous amount of genetic diversity, such as the black-footed ferret and the northern white rhino. Such investigations, however, should be conducted under the mantle of preserving modern biodiversity rather than conjuring extinct species from the grave.

The suggestion that we humans have a moral obligation to resurrect the species that died out by our hand resonates with our sense of justice. Yet the revival of a single extinct beast in a lab does not mark the return of a species, and creating viable populations of extinct animals that could flourish in modern ecosystems is a far more difficult challenge. Surely we have a greater duty to species currently on the brink than to the ones that our ancestors wiped out centuries or millennia ago.