Nature is in trouble, and it’s only getting worse. As species disappear at a rate not seen in 10 million years, more than 1 million species are currently on the brink.
Scientists say that humans are driving this extinction crisis through activities that pollute animal habitats, pollute nature and promote global warming. A new global accord to protect nature that took place on December 19 has the potential to help, and scientists are urging the world’s countries to make sure the deal is successful.
When an animal species is lost, along with it is lost a whole range of genes, behaviours, activities and interactions with other plants and animals that took thousands or millions – even billions – of years to evolve. May take years.
Whatever role they play within an ecosystem is also lost, whether it is pollinating certain plants, churning out nutrients in the soil, fertilizing forests or keeping other animal populations in check. . If that function was important to the health of an ecosystem, the disappearance of animals could alter a landscape.
Lose too many species and the consequences can be catastrophic, causing an entire system to collapse.
gone forever
Over the past five centuries, hundreds of unique animals have disappeared around the world, such as the flightless dodo bird that was killed off the island of Mauritius in the late 1600s.
In many cases, humans were to blame – first by fishing or hunting, as in the case of the South African zebra subspecies quagga that was hunted to its end in the late 19th century – and more recently Through activities that pollute, disrupt or control wild habitats.
Before a species becomes extinct, it may already be considered “functionally extinct” – there are not enough individuals left to ensure the survival of the species. Recent extinctions have allowed humans to interact with the last known individuals of some species, known as “andlings”. When they go, so do those evolutionary lines—as happened in these iconic cases:
The last known individual of Rab’s fringe-limbed tree frog was “Toffee”. A few dozen of its species were wiped out in the wild in Panama by the chytrid fungus. In his enclosure at the Atlanta Botanical Garden, he was calling in vain for a mate who didn’t exist. He died in 2016.
The story of the passenger pigeon “Martha” is a cautionary tale for conservation: there were still millions of passenger pigeons in the 1850s, but they were eventually hunted to extinction because conservation measures were taken only after the species had not recovered Were. Martha, the last, died in 1914 at the Cincinnati Zoo.
“Lonesome George”, found in 1971, was the last Pinta Island tortoise from Ecuador. From the 17th century, approximately 200,000 individuals were hunted for their meat. Later, they had to struggle for food after goats were introduced to the island in the 1950s. Before George died in 2012, scientists tried to save the species through captive breeding.
“Ben” or “Benjamin” was the world’s last known thylacine, a marsupial carnivore also known as the Tasmanian tiger. The animal was given protective status in 1936, just two months before Benjamin’s death at the Beaumaris Zoo in Tasmania.
on the verge
There are some species that may soon be confined to their end. The world’s smallest porpoise – Mexico’s critically endangered vaquita – is down to just 18 individuals in the wild, as populations have been devastated by fishing nets.
The northern white rhino subspecies, the second largest land mammal after elephants, shows no hope of recovery after the death of the last male in 2018. Only a female and her daughter survive.
Scientists say that these stories of endlings matter precisely because so many extinction events go unnoticed.
Paula Ehrlich, President and CEO of EO Wilson Biodiversity, said, “Somewhere at the core of our humanity, we recognize these creatures, we are moved by their story, and we feel compassion — and perhaps a moral compulsion.” Also – to help.” foundation.
He said that the northern white rhinoceros is not part of the world. It’s a world in itself—its own ecosystem—grazing through fields, fertilizing the land where it walks, insects landing on its skin, and then feeding on those insects with birds.
Ehrlich said, “Understanding everything that an animal is and does for the world helps us to understand that we are also a part of nature – and we need nature to survive.”
extinction over time
Unlike Andlings, most species disappear into the wild without people ever seeing them.
Scientists have counted 881 animal species that have gone extinct since about 1500, according to the first records kept by the International Union for Conservation of Nature (IUCN) – the global scientific authority on the status of nature and wildlife. This is an extremely conservative estimate for species extinctions over the past five centuries, however, as it represents only resolved cases with a high degree of certainty.
If we include animal species that scientists suspect may be extinct, the number rises to 1,473. The standard for declaring a species extinct is too high – a serious task that scientists are already reluctant to undertake.
“It’s hard to prove that you can’t find it,” said Sean O’Brien, an ecologist who heads the NatureServe nonprofit group to establish definitive data on North American species. I don’t want to declare it extinct because it sounds like a failure.”
Among terrestrial vertebrates, or land animals with a backbone, 322 species have been declared extinct since 1500. Add in the number of possibly extinct species and the tally comes to 573.
For moisture-loving amphibians, which are vulnerable to both pollution and drought, things are looking particularly bleak, with extinction rates rising over the past few decades. According to a 2015 study in the journal Science Advances, only 37 species have been declared extinct with a high degree of certainty since 1500. But scientists suspect that more than 100 others have disappeared over the past 30-40 years.
The number of last seen has increased over time, especially since the mid-19th century with the onset of the Industrial Revolution. This suggests that the threats to animals are increasing, but also that our knowledge of nature is improving as we study and survey more species.
Among them are several notable species that have disappeared since the 1500s. The dodo was last seen in 1662, less than 65 years after it was first recorded. The Pinta Island tortoise was last seen in the wild in 1972.
Some extinctions have prompted public outcry, such as the declaration of extinction in 2016 for the tiny Christmas Island pipistrelle bat species, last seen in 2009. It was Australia’s first recorded mammal extinction in 50 years.
Losing hundreds of species in 500 or so years may not seem significant when there are still millions of people living on the planet. But the speed at which species are going extinct now is unprecedented in the last 10 million years.
“We are losing species faster now than they are evolving,” O’Brien said.
mass extinction
Many animals have become extinct either naturally or for reasons unrelated to human activities. In a healthy environment, as species naturally die out, new species develop – and an evolutionary balance is maintained.
This turnover depends on what scientists consider a normal or background extinction rate.
But when the extinction rate becomes so high that more than 75% of the world’s species become extinct within a relatively short time frame of less than 2 million years, it is considered a mass extinction event.
This has happened five times in the past half billion years, which we know through the study of Earth’s fossil record – the animal remains buried with layers upon layers of sediment over time. When a layer containing a large and diverse number of animals is found, scientists can see that a mass die-off has occurred.
Scientists have warned that we have entered the sixth mass extinction.
According to a 2015 paper in Science Advances, under a typical extinction rate scenario, it would have taken at least 800 years and as long as 10,000 years for the high number of vertebrate extinctions.
“Despite our best efforts, the extinction rate is still estimated to be 1,000 times higher than it was before humans entered the stage,” Ehrlich said. “At this rate, it will be gone by the end of the half century.”
unknown and still in danger
As bad as it sounds, scientists say the reality is worse. Looking only at species extinction doesn’t give the full picture, partly because scientists are so conservative in saying that a species is gone. For example, even though the touffie was the last known individual of its kind, the IUCN still lists its species as “critically endangered, possibly extinct”.
More importantly, there is a vast reservoir of species that we have yet to discover. Scientists have identified about 1.2 million species in the world, but it is estimated that there are about 8.7 million. That leaves about 7.5 million species that we think are out there but know nothing about – whether they’re in trouble or not.
“Knowing what we do about climate change and the impact of habitat loss, it is hard to imagine that thousands if not millions of species are not already in the process of extinction,” O’Brien said.
Conservation gives hope as population declines
The IUCN uses several categories to describe the status of a species, as a way of identifying which are in trouble and when to help. But a species being listed as “least concern” or “near threatened” does not mean that its population is stable.
For example, African lions have been listed as “vulnerable” for decades, but their numbers declined by 43% in 1993–2014, when the last population data was available. Dugongs, the chubby marine mammals also known as sea cows, are listed globally as “vulnerable” even as their dwindling populations in East Africa and New Caledonia were listed as “endangered” in December. It was updated as
A decline in one or more populations of a species may mark the beginning of an extinction trend.
No matter how dire the situation on a global scale, there are reasons for hope. The new Kunming-Montreal Global Biodiversity Framework, adopted in December, will guide global conservation efforts over the decade to 2030.
“It’s overwhelming to think that these species are right on the edge,” O’Brien said.
Between 1993 and 2020, conservation measures such as habitat restoration or captive breeding helped prevent the extinction of up to 32 bird species and 16 mammals worldwide, according to conservative estimates in a 2020 study published in the journal Conservation Letters.
“Science is democratizing information for every country to know what it needs to do,” said Ehrlich of the Wilson Foundation. O. Wilson advocated conserving half the planet and estimated that it would save 85% of the world’s species.
“We humbly need to do the best we can to protect them now,” Ehrlich said.
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