How fast are species going extinct

The species' known range had suddenly expanded. This kind of citizen science has exploded in recent years because of smartphones.

Now, according to a new review of research about Earth's biodiversity, it's giving conservationists hope that new technology can slow extinctions. 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 University and 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. 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.

Peter Crane , dean of Yale's School of Forestry and Environmental Studies, said by email that the new "paper does huge service in pulling together the latest thinking on species extinctions for very diverse groups of organisms.

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.

Calculating extinction rates can be difficult, in part because no one knows exactly how many species there are. Scientists have identified at least 1. And according to the study, at least , 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. Applying the same statistical approach to extinction data revealed a rate of to 1, species lost per million per year, mostly due to human-caused habitat destruction and climate change. To calculate the rate of extinction before modern humans evolved, about , 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.

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.

But others have been more cautious about reading across taxa. They say it is dangerous to assume that other invertebrates are suffering extinctions at a similar rate to land snails. Mark Costello, a marine biologist of the University of Auckland in New Zealand, warned that land snails may be at greater risk than insects, which make up the majority of invertebrates.

The same should apply to marine species that can swim the oceans, says Alex Rogers of Oxford University.

Only 24 marine extinctions are recorded by the IUCN, including just 15 animal species and none in the past five decades. Some think this reflects a lack of research. Whatever the drawbacks of such extrapolations, it is clear that a huge number of species are under threat from lost habitats, climate change, and other human intrusions. And while the low figures for recorded extinctions look like underestimates of the full tally, that does not make the high estimates right.

Can we really be losing thousands of species for every loss that is documented? Some ecologists believe the high estimates are inflated by basic misapprehensions about what drives species to extinction. So where do these big estimates come from? The biologists argued, therefore, that the massive loss and fragmentation of pristine tropical rainforests — which are thought to be home to around half of all land species — will inevitably lead to a pro-rata loss of forest species, with dozens, if not hundreds, of species being silently lost every day.

The presumed relationship also underpins assessments that as much as a third of all species are at risk of extinction in the coming decades as a result of habitat loss, including from climate change. He is not alone. Instead they hunker down in their diminished refuges, or move to new habitats. In his new book, On The Edge , he points out that El Salvador has lost 90 percent of its forests but only three of its forest bird species.

Meanwhile, the island of Puerto Rico has lost 99 percent of its forests but just seven native bird species, or 12 percent. Some ecologists believe that this is a temporary stay of execution, and that thousands of species are living on borrowed time as their habitat disappears. If nothing else, that gives time for ecological restoration to stave off the losses, Stork suggests.

But we are still swimming in a sea of unknowns. For one thing, there is no agreement on the number of species on the planet. Researchers have described an estimated 1. But, allowing for those so far unrecorded, researchers have put the real figure at anywhere from two million to million. That may be a little pessimistic. Among the most critical steps is the 30x30 campaign, which will protect wildlife places and wildlife habitat, including oceans, rivers, forests, deserts and swamps. Unlike past mass extinctions, caused by events like asteroid strikes, volcanic eruptions, and natural climate shifts, the current crisis is almost entirely caused by us — humans.

In fact, 99 percent of currently threatened species are at risk from human activities, primarily those driving habitat loss, introduction of exotic species, and global warming [ 3 ]. Because the rate of change in our biosphere is increasing, and because every species' extinction potentially leads to the extinction of others bound to that species in a complex ecological web, numbers of extinctions are likely to snowball in the coming decades as ecosystems unravel.

Species diversity ensures ecosystem resilience, giving ecological communities the scope they need to withstand stress. Thus while conservationists often justifiably focus their efforts on species-rich ecosystems like rainforests and coral reefs — which have a lot to lose — a comprehensive strategy for saving biodiversity must also include habitat types with fewer species, like grasslands, tundra, and polar seas — for which any loss could be irreversibly devastating.

And while much concern over extinction focuses on globally lost species, most of biodiversity's benefits take place at a local level, and conserving local populations is the only way to ensure genetic diversity critical for a species' long-term survival. In the past years, we know of approximately 1, species that have gone extinct, from the woodland bison of West Virginia and Arizona's Merriam's elk to the Rocky Mountain grasshopper, passenger pigeon and Puerto Rico's Culebra parrot — but this doesn't account for thousands of species that disappeared before scientists had a chance to describe them [ 4 ].

Nobody really knows how many species are in danger of becoming extinct. Noted conservation scientist David Wilcove estimates that there are 14, to 35, endangered species in the United States, which is 7 to 18 percent of U. The IUCN has assessed roughly 3 percent of described species and identified 16, species worldwide as being threatened with extinction, or roughly 38 percent of those assessed. In its latest four-year endangered species assessment, the IUCN reports that the world won't meet a goal of reversing the extinction trend toward species depletion by [ 5 ].

What's clear is that many thousands of species are at risk of disappearing forever in the coming decades. Scientists estimate that a third or more of all the roughly 6, known species of amphibians are at risk of extinction [ 6 ]. Frogs, toads, and salamanders are disappearing because of habitat loss, water and air pollution, climate change, ultraviolet light exposure, introduced exotic species, and disease.

Because of their sensitivity to environmental changes, vanishing amphibians should be viewed as the canary in the global coal mine, signaling subtle yet radical ecosystem changes that could ultimately claim many other species, including humans.

BIRDS Birds occur in nearly every habitat on the planet and are often the most visible and familiar wildlife to people across the globe.

As such, they provide an important bellwether for tracking changes to the biosphere. Declining bird populations across most to all habitats confirm that profound changes are occurring on our planet in response to human activities.

A report on the state of birds in the United States found that 31 percent of the species in the country are of conservation concern [ 7 ]. Habitat loss and degradation have caused most of the bird declines, but the impacts of invasive species and capture by collectors play a big role, too. FISH Increasing demand for water, the damming of rivers throughout the world, the dumping and accumulation of various pollutants, and invasive species make aquatic ecosystems some of the most threatened on the planet; thus, it's not surprising that there are many fish species that are endangered in both freshwater and marine habitats.

The American Fisheries Society identified species of freshwater or anadromous fish in North America as being imperiled, amounting to 39 percent of all such fish on the continent [ 8 ].