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"Our findings are potentially good news for the conservation of global biodiversity," said lead author Mark Costello from The University of Auckland's Leigh Marine Laboratory.
Over the last decade researchers have described 17,5000 new species a year on average, most of which were insects (especially beetles). But every year, scientists still find new mammals, birds, reptiles, and amphibians. However, predictions that there are up to 100 million species on Earth made it appear hopeless that scientists would ever describe them all, especially before they vanished. However, the new paper argues that most likely there are between 2-8 million species on Earth.
"Previous estimates of 30 to 100 million based on potential deep-sea diversity and estimates of insect host specificity now seem highly unlikely," the researchers write. Costello says such estimates may have actually hurt conservation efforts.
The researchers argue that with just a slight increase in effort, 2 million species could be described by 2050, and 3.5 million species by 2100.
So far, around 1.5 million species have been named and described, since the Swedish scientist, Carl Linnaeus, kicked off the effort in the 18th Century. Linnaeus was the first of the taxonomists, i.e. scientists devoted to the formal discovery and description of the world's species. In recent years, many scientists in Europe and North America have lamented that taxonomy was dying, and with it our chance to catalogue global biodiversity. However, the paper in Science found the opposite to be true: taxonomy is thriving like never before.
"The numbers of taxonomists may be decreasing in some [... ] countries that formerly led the field of taxonomy [...]," the scientists write, but add that "the increasing number of taxonomists is partially due to the increase in taxonomists based in South America and Asia."
The researchers believe that there may be two-to-three more taxonomists working now than in the 1960s. Amateur taxonomists are also on the rise for some types of species.
In addition, while every year brings more-and-more species added to the IUCN Red List of threatened species, the scientists say that documented extinctions still remain relatively low.
"We do not dispute that we are in a human caused mass extinction phase with many species committed to extinction, but actual extinctions have been fewer than arguably expected," they write, arguing that fewer species have gone extinct than sometimes reported due to conservation efforts, survival in degraded habitats, and extinction debt, i.e. some species that are doomed to eventual extinction still hang-on in small, dwindling populations.
"Of course, there will have been some species which have disappeared without being recorded, but not many we think," co-author Nigel Stork with Griffith University said. The scientists argue that extinction rates are likely less than 1 percent every decade, meaning that if 5 million species inhabit Earth, up to 50,000 species could have vanished this decade. Still, other scientists believe the extinction rate remains closer to 5 percent a decade.
Whatever the current extinction rate, the scientists say the it is likely to go higher, especially as the impacts from climate change increase.
"Local threats, such as habitat loss, hunting, and harvesting, are now acting synergistically with climate change," they write.
Given this the scientists recommend stepping up taxonomy efforts. They embrace a previous plan that argued that with an annual investment of $0.5 to $1 million, taxonomy could increase by ten times. According to the authors, this would likely "result in the description of all species within 50 years."
Still, the scientists write, "the scale of this taxonomic challenge must not be underestimated. A 1-month survey of seabed in New Caledonia found 127,652 specimens and 2738 species of mollusks, of which 80 percent were new to science. A sample of 24,000 specimens of insects from the canopy of 10 trees in Borneo took 2 years to sort to 5,000 morphospecies."
The scientists conclude that with only a "modest increase" in taxonomic and conservation efforts "most species could be discovered and protected from extinction."
New species of tree frog from Vietnam: Helen's tree frog. Photo courtesy of Jodi Rowley.
New species of super tiny chameleon from Madagascar: Juvenile Brookesia micra on match.
CITATION: Mark J. Costello, Robert M. May, Nigel E. Stork. Can We Name Earth’s Species Before They Go Extinct? Science. Volume 339. 2013.
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