Before releasing the frog into a nearby pond, Trouern-Trend uploaded a picture of it to the mobile app iNaturalist, which connects a worldwide community of people who report sightings of animals and plants online.
App users informed him that he'd found a lemon-yellow tree frog (Hyla savignyi)—and noted that scientists had never recorded one outside ofKurdistan (map). The species' known range had suddenly expanded.
That's good news, because according to a review published on May 29 in the journal Science, current extinction rates are up to a thousand times higher than they would be if people weren't in the picture.
Study leader Stuart Pimm, a conservation ecologist at Duke Universityand contributor to National Geographic's News Watch blog, and his colleagues analyzed various data sources—in particular the International Union for Conservation of Nature's Red List of Threatened Species, a global inventory of species—to produce the first major review of extinction data. (See: "20,000 Species Are Near Extinction: Is It Time to Rethink How We Decide Which to Save?")
Mobile apps, GIS satellite data, and online crowdsourcing, Pimm says, may be a partial antidote to the problem. Through these technologies, "we're mobilizing millions of people around the world, and we're on the cusp of learning very much more about where species are than we have ever known in the past." That's critical, he explains, because now "we know where the species are, we know where the threats are, and—even though the situation is very bleak—we are better able to manage things."
Crane, who was not involved in the study, agreed that new technologies like remote sensing and more comprehensive databases "will not only improve the effectiveness of conservation investments, but will also strengthen monitoring of change in species-level biodiversity through time."
How Many Out There?
Calculating extinction rates can be difficult, in part because no one knows exactly how many species there are. Scientists have identified at least 1.9 million animal species, and possibly millions more have yet to be named. And according to the study, at least 450,000 plant species likely exist.
Pimm says conservationists can calculate the extinction rate of the known species by keeping track of how many die out each year.
The technique is similar to that used to figure out a country's death rate: track the number of people who die in a given population each year, scaled to that population. Mortality rates are usually calculated as the number of deaths per thousand people per year.
To calculate the rate of extinction before modern humans evolved, about 200,000 years ago, Pimm and his colleagues reviewed data from fossil records and noted when species disappeared, then used statistical modeling to fill in holes in the record. That analysis revealed that before humans evolved, less than a single species per million went extinct annually.
The study authors suspect that the extinction rate will only increase if trends continue—possibly resulting in what scientists call the sixth mass extinction in Earth's history. (Related: "The Sixth Extinction: A Conversation With Elizabeth Kolbert.")
Another conclusion of the study that can't be ignored, says Yale's Crane, is "that there remain huge gaps in knowledge. At least for the most diverse groups of organisms on Earth, the urgent need to clarify how many species there are, where they live, and how their populations are changing remains a key impediment."
To Jenny McGuire, a postdoctoral research scientist at the University of Washington's School of Environmental and Forest Sciences who wasn't involved in the study, the results aren't surprising.
Though some might quibble about the exact rate, she says, "in general scientists are in agreement that we're at a period of heightened extinction risk and rates, and that's been occurring nearly since humans have come onto the landscape."
She says that people can vote for policies that lessen the impact of climate change, which is hitting the oceans particularly hard by raising the water's pH and dissolving the shells of many marine animals. People can also encourage their governments to connect one nature reserve to another.
Pimm says protected areas, the "frontline of conservation," have kept extinction rates of mammals, birds, and amphibians 20 percent lower than they would have been without refuges. Nearly 13 percent of Earth's land has been set aside, but only 2 percent of the ocean is part of a refuge.