Scientists warn: Sixth mass extinction "may have begun"

Life on Earth has been destroyed by at least five mass extinctions over the past 450 million years, which are often defined as catastrophes that wipe out more than 75 percent of species in a short period of time. Many scientists have suggested that we are entering the sixth mass extinction, this time caused by human activity, although the validity and consequences of this claim are still debated.

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Now, a team led by Robert Cowie, a research professor at the Pacific Center for Biological Sciences at the University of Hawaii, believes that "the sixth mass extinction has already begun on land and freshwater and seems to be becoming more and more likely." The study was published in Biological Reviews.

"We think the sixth mass extinction may have already begun and present arguments to refute those who deny it," the research team wrote in the article. The panel also included biologist Philippe Bouchet and Benoît Fontaine of the National Museum of Nature in Paris, France.

"Denying that it is nothing more than a moth to a fire in the face of a rapidly accumulating large amount of data should no longer be left to doubt whether it is really happening," the researchers added.

Cowie and his colleagues mention a large number of studies and taxonomies of species extinctions of various ethnic groups, but this article revolves around their study of mollusks. Molluscs are a family of invertebrates that include snails, clams, and slugs. This focus offsets the disproportionate attention received by vertebrates such as birds and mammals on the International Union for Conservation of Nature's (IUCN) Red List of Threatened Species, as well as other conservation efforts.

"The IUCN's information on the extinction of birds and mammals is probably fairly accurate," Cowei said in a phone call, "however, they did not assess any of the 95 percent of invertebrates that make up animal diversity, except for an assessment of the tiny tiny fraction of invertebrates such as insects and snails and spiders and crustaceans." ”

Cowei notes that invertebrates provide more random samples of biodiversity.

Past studies have used IUCN data to refute the claim that we are entering a sixth mass extinction. Cowie and his colleagues disprove this hypothesis by compiling the extinction rates of land snails and slugs. Extrapolating from these data, the team concluded that between 7.5 and 13 percent of species may have gone extinct since 1500, a figure consistent with many other estimates of catastrophic biodiversity loss due to human pressure.

"The bottom line is that all these estimates that people are making suggest that the rate of extinction is much higher now than it was in the past," Cowie said.

While many marine species are also threatened by human activities, this extinction crisis is far more pronounced on land than in the ocean. Extinctions in island ecosystems such as Hawaii also occur more quickly than in continental biomes.

In addition to sounding the alarm about a possible mass extinction, Cowie and his colleagues have presented a series of rebuttals that they say dilute the severity of humanity's pressure on the world's species, and even suggest that humans should use these ecological changes for our own benefit.

The team argues that this "laissez-faire attitude toward the current extinction crisis is morally wrong, and they also advocate for more urgent measures to address species losses caused by human activities."

"I feel obligated to give an opinion on what we feel should be done in this crisis situation. I'm not just going to come up with data and say that's it. I'm going to say what we should do to solve this problem because it's an important question," Cowie said.

Ultimately, the team acknowledges that conservation efforts may feel futile in the face of this huge problem and suggests that more effort should be spent on efforts to collect specimens of species that are disappearing lest they disappear forever.

"We don't think there's a positive ending; we think it's a disaster," Cowie concludes, "and we feel like the most important thing we can do for the future is preserve as many of these species as possible in museums so that in 200, 300 or 500 years, people can still say it's something that once existed on Earth." I firmly believe that. ”