Scientists observe an unexpected acceleration of mass extinctions

Scientists observe an unexpected acceleration of mass extinctions

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Do I have to say it again? The sixth extinction has already begun. Scientists tell us and say it again: this extinction is not due to a catastrophic natural event, but to man. The unnatural loss of biodiversity is accelerating, and if it continues, the planet will lose vast ecosystems and the basic necessities they provide, including fresh water, pollination, and the control of pests and diseases. The bad news this week is that this collapse is accelerating much faster than most experts predicted. We will lose 500 species of terrestrial vertebrates over the next 20 years - the equivalent of the losses the planet naturally experiences in 16,000 years!

According to research published this 1er June in Proceedings of the National Academy of Scienceswe're faster and closer to the point of collapse than the scientists feared. The rate of extinction of terrestrial vertebrate species is significantly higher than previous estimates, and the critical window of opportunity to prevent mass losses will close much sooner than expected - in 10 to 15 years.

We are eroding the planet's ability to sustain human life and life in general... "warns Gerardo Ceballos, an ecologist at the National Autonomous University of Mexico and lead author of the new study.

The current rate of extinctions far exceeds the rate that would occur naturally," said Dr. Ceballos and his colleagues. Scientists know that 543 species have become extinct over the past 100 years, a figure that would normally take 10,000 years to accumulate. « In other words, every year over the last century we have lost the same number of species as are generally lost in 100 years. ", said Dr. Ceballos.

If nothing changes, about 500 more species of terrestrial vertebrates are likely to become extinct in the next two decades alone, representing total losses equivalent to those that would have occurred naturally over 16,000 years.

To determine how many species are on the brink of extinction, Dr. Ceballos and co-authors Paul Ehrlich, a conservation biologist at Stanford University, and Peter Raven, an environmentalist at the Missouri Botanical Garden, turned to population data for 29,400 species of terrestrial vertebrates compiled by the International Union for Conservation of Nature. Of these species, 515 - or 1.7 % - are Critically Endangered, they found, with fewer than 1,000 individuals remaining. About half of these species have fewer than 250 individuals.

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Researchers also examined species with populations between 1,000 and 5,000 individuals. When scientists added these 388 species to their initial analysis, they found a geographical overlap of 84 % - mainly in the tropics - with species in the Critically Endangered group.

Domino effect

The loss of some of them will likely trigger a domino effect that will send others in a downward spiral, ultimately threatening entire ecosystems, according to the authors. Dr. Ceballos likened this process to removing bricks from the wall of a house. « If you remove a brick, nothing happens - maybe it just gets louder and wetter inside. " he says. " But if you take too much off, your house will eventually collapse... ». Ecologists must therefore consider that all species with populations of less than 5,000 individuals are in danger of extinction," concluded Dr. Ceballos and his colleagues.

This is a substantial increase in what we have generally considered to be at risk... " Katie Bays, co-founder of the consulting firm Sandhill Strategy, said to the New York Times Daniel Blumstein, an ecologist at the University of California at Los Angeles, who did not participate in the research. The new study also emphasizes the importance of protecting individual animal populations, not just a particular species. Based on an analysis of the current and historical ranges of critically endangered species, the researchers calculated that more than 237,000 individual populations have become extinct since 1900.

As populations disappear from geographical areas, the function of the species is also disappearing. The disappearance of bees in one geographical area, for example, would be an economic blow of billions of euros, but the species itself would still survive somewhere else in the world. « Declining populations of common species - top predators, large-bodied herbivores such as rhinoceroses, pollinators and others - have important effects on the functioning of ecosystems even when they are far from extinction. "said Rebecca Shaw, Chief Scientist of the World Wildlife Fund, who was not involved in the research.

Dr. Ehrlich pointed out that the general conclusions of the study were almost certainly a gross underestimate of the true scope of the extinction problem. Their analysis did not consider aquatic or invertebrate plants or species, and included only about 5 % of terrestrial vertebrates for which scientists have population data.

Realizing

The issue of extinction is in the media, and the general public knows what it is all about. But are they fully aware of it? « The fact that so few people are aware of the impending crisis is a cause of the crisis itself. "said the authors of the study. Most people don't think the loss of a small animal or plant is a big deal. What they don't know is that the role of a particular plant or animal in an ecosystem is only fully apparent after the species in question is gone.

Carrier pigeons, for example, were once counted in billions. Their voracious appetite for seeds limited the population growth of other seed-eating species, including white-legged mice - the natural reservoir of the bacteria that cause Lyme disease. After the extinction of the carrier pigeon, populations of white-legged mice exploded and the risks to human health increased. Impacts of the extinction of the carrier pigeon, write researchers in Science, " are still being felt a century after the death of the last homing pigeon. ".

As humans continue to encroach on nature and wildlife, Dr. Ceballos and his colleagues warn of a series of cascading impacts - including more frequent outbreaks of new diseases and pandemics. The coronavirus that started the pandemic came from a wild animal, according to most scientists. « The Covid-19 vaccine was the natural habitat of the coronavirus... ", says Dr. Ceballos. « The pandemic is an excellent example of how we have mistreated nature..."

With enough species loss, ecosystems will eventually collapse, destabilizing economies and governments and triggering famines and refugee crises. « But there are steps that can be taken now."said Dr. Ceballos. « The most fundamental problem is to reduce the scale of human enterprise, in particular its demands on the biosphere for consumption. ", Dr. Ehrlich agrees.

Achieving these changes will require the election of leaders who give priority to the environment, the redistribution of resources and the slowing of human population growth. To help organize these efforts, researchers Ceballos and Ehrlich have launched a new global initiative: Stop Extinction. It aims to provide a framework for the creation of new national agreements, as well as tools to educate and mobilize the public on the ongoing extinction crisis.

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We all need to understand that what we do in the next five to ten years will define the future of humankind« they hammered.

It's high time to react " wrote Gilles Boeuf in UP', " and to consider as important that climate change is accelerating the loss of biodiversity. We only consume organic and only cooperate with organic! So we must admit once and for all our inseparable relationship to life on the planet and to biodiversity: every time we attack it, we attack ourselves (and our economy).. "The biologist, former director of the Museum of Natural History in Paris concluded: " For a species that has chosen to be called sapiens, that sounds pretty stupid! Let us deserve during this century this term that we, who have still not gone beyond the Homo faber stage. "

You can find examples of this stupidity all over the planet. The latest one is attributed to Donald Trump, a master of the subject. As we write this, he is about to sign an order-in-council directing government agencies to abandon long-standing environmental laws that protect the environment, biodiversity and prevent the loss of endangered species. According to the Washington PostThe order will allow the Trump administration, under the pretext of "current economic emergency", to expedite federal approval of new mines, highways, pipelines. Clearly, Trump's America doesn't care about the sixth extinction.

Sources: PNAS, New York Times, Science

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