Even some species found while still alive are already on the brink. In fact, research suggests that it is the newly described species that are most at risk of becoming extinct. Many new species are only now emerging discovers because they’re rare, isolated, or both — factors that also make it easier to eradicate them, Fraga said. For example, botanist Denise Molmou of the National Herbarium of Guinea in Conakry discovered a new plant species in Guinea in 2018 that, like many of its relatives, appeared to inhabit a single waterfall, enveloping rocks amid bubbling, aerial waters. Molmou is the last person known to have seen alive.
Just before her team published their findings in the Kevin Bulletin last year, Cheek viewed the waterfall’s location on Google Earth. A reservoir, created by a hydroelectric dam downstream, had overflowed the falls, surely drowning all the plants there, Cheek said. “If we hadn’t gotten in there and Denise hadn’t gotten that specimen, we wouldn’t know that species existed,” he added. “I felt sick. I felt, you know, it’s hopeless, what’s the point? Even if the team had known at the time of discovery that the dam was going to wipe it out, Cheek said, “it would be pretty hard to to do something about it.”
While extinction is likely in many of these cases, it is often difficult to prove. The IUCN requires targeted searches to explain extinction — something Costa still plans to do for the killifish four years after its discovery. But these surveys cost money and are not always possible.
Meanwhile, some scientists have turned to computational techniques to estimate the magnitude of extinctions in the dark, extrapolating the rate of species discovery and extinction among known species. When Chisholm’s group applied Applying this method to Singapore’s estimated 195 bird species, they estimate that 9.6 undescribed species have disappeared from the area in the past 200 years, in addition to the disappearance of 58 known species. For butterflies in Singapore, about good for dark extinction doubled the extinction of 132 known species.
With similar approaches, another research team estimated that the proportion of dark extinctions could account for up to just over half of all extinctions, depending on the region and species group. Of course, “the main challenge in estimating dark extinction is that it is just that: an estimate. We can never know for sure,” noted Quentin Cronk, a University of British Columbia botanist who has produced similar estimates.
Given current trends, some scientists doubt whether it is even possible to name all species before they become extinct. For Cowie, who expressed little optimism that the extinction will recede, the priority should be collecting species, especially invertebrates, from the wild so that there will at least be museum specimens to mark their existence. “It would be a disservice to our descendants if we just let everything disappear, so that in 200 years no one will know about the biodiversity – the real biodiversity – that developed in the Amazon, for example,” he said. “I want to know what lives and lived on this earth,” he continued. “And it’s not just dinosaurs and mammoths and stuff; it’s all these little things that keep the world going.”
Other scientists, like Fraga, find hope in the fact that the extinction conjecture is just that: a conjecture. As long as habitat remains, it is unlikely that species considered extinct will be rediscovered and returned to healthy populations. In 2021, Japanese scientists stumbled upon the fairy lantern Thismia kobensisa fleshy orange flower known only from a single specimen collected in 1992. Efforts are now being made to protect the site and grow specimens for preservation.
Fraga is tracked down observations from a monkey flower species she identified in herbaria specimens: Erythranthe marmorata, which has bright yellow petals with red spots. Ultimately, she said, species aren’t just names. They are participants in ecological networks, upon which many other species, including humans, depend.
“We don’t want museum specimens,” she said. “We want to have thriving ecosystems and habitats. And to do that, we need to make sure these species thrive in, you know, populations in their ecological context, not just living in a museum.”
