The Sixth Mass Extinction

A study published nearly two years ago warned that “This current ‘biological annihilation’ underlines the seriousness for humanity of Earth’s ongoing sixth mass extinction”.

This was a study by Gerardo Ceballos, Paul Ehrlich and Rodolfo Dirzo called ‘Biological annihilation via the ongoing sixth mass extinction signalled by vertebrate population losses and declines’ published in the July 2017 journal of the US National Academy of Sciences.

The study is based on a sample of 27,600 terrestrial vertebrate (possessing a spinal column) species and focusses on detailed analysis of 177 mammal species between 1900 and 2015. The study demonstrates that as bad as the statistics with regards to endangered species are, the situation is actually much worse. We would be fatally wrong to think that we are entering a period of species loss that is going to occur over a few hundred years and therefore that we have more than enough time to react at some future date.

Just counting species lost or under threat is not enough. We need to look deeper at the populations of species and their geographic dispersal. It is the populations in one or many locations on Earth that make up a species. These populations live in different ecosystems and in the large majority of cases are unable to migrate to other welcoming habitats. In any case all habitats on earth are under severe stress from humans. Human activity and exploitation as well as climate change and ocean acidification is causing populations of vertebrate animals and their habitats to crash.

The study’s research reveals that this is in fact happening at an accelerated rate. We will soon enter a time period where most of the animal populations will reach unsustainably low numbers segregated in their terminally degraded habitats scattered around the globe. Entire species will then start to disappear at such a fast rate that the momentum will be unstoppable and irreversible. This is not a probability this is a promise. Moreover the study makes it clear that all of this is a real and present threat to all of us “Dwindling populations sizes and ranges amount to a massive anthropogenic (caused by people) erosion of biodiversity and of ecosystem services (functions) essential to civilisation”.

The Earth’s sixth mass extinction is more severe that would appear than by just counting lost or surviving species. Populations of nearly all species are in decline and their natural habitat, that is the only place where these species can survive, is decreasing substantially. The study finds that 32% of vertebrate species are decreasing both in population and habitat size.

Of the 177 mammals selected for detailed analysis all have lost 30% or more of their habitat and more than 40% of the species have suffered a population loss of greater than 80%. The study indicates that the Earth is experiencing massive animal population declines as well as disappearance of whole populations in parts of the world. This will have negative cascading consequences on ecosystem functioning and its life supporting characteristics ultimately threatening civilisation itself. This is not an idle statement. As air and ocean pollution and toxic contamination of virtually everything by industry becomes widespread and climate change takes a grip with wide temperature fluctuations, this will cause an unprecedented migration of humans across the globe causing conflict and death.

The biological diversity that modern humans were born into two hundred thousand years ago is the richest ever in the history of the planet. Humans have been systematically destroying this biodiversity over millennia at an increasing rate that now has reached a frightening acceleration. In the last one hundred years at least two hundred species of vertebrates have to our knowledge become extinct. At the normal extinction rate of the last two million years two hundred species would otherwise have taken ten thousand years to become extinct.

People buy into the convenient delusion that the number of species becoming extinct is not that large and we have time, in any case technologies, such as cloning, can bring species back to life. We need to understand that species are made up of populations and populations are made up of individuals. This is true of people as it is of terrestrial and marine animals. We are causing the death of huge numbers of individual animals, causing populations to collapse and bringing all species closer to extinction.

Habitats are made up of trees and plants, ground water, different terrains and climate. We are contaminating, depleting and diverting the ground water. We are destroying plants and trees over huge areas to make way for agriculture and human infrastructure and settlements. Our carbon emissions have caused global warming and ocean acidification.

Now animals and habitats interact intimately and a degradation of one, degrades the other. So, no, the situation is not ok and time is running out. There are 7,500 Sumatran Orang-utans, 800 Tapanuli Orang-utans and 7,500 cheetah left in the world. There are about 20,000 lions left alive. Lion populations are extinct in 26 African countries and have vanished from over 90% of their historic range.

Species, such as the Turtle Dove (Gamiem), with populations running into tens of thousands or even hundreds of thousands are also decreasing worryingly. This is a concern as these populations are living in increasingly degraded habitats that are under severe threat by humans. In this situation a species population of 100,000 could disappear in a decade.

The study points out that population declines are leading to rapid species extinctions and that “these assaults are causing a vast reduction in the fauna and flora of our planet. The resulting biological annihilation will also have serious ecological, economic and social consequences, humanity will eventually pay a very high price for the decimation of the only assemblage of life that we know of in the universe.”

The study estimates that as much as 50% of the number of animal individuals that once shared the Earth with us are already gone as are billions of populations.

The study concludes that the causes of population extinctions that then lead to species extinctions are “habitat conversion, climate disruption, overexploitation (killing), toxification (poisoning), species invasions, disease, and wars (potentially nuclear war) – all tied into one another in complex patterns and usually reinforcing each other’s impacts. Much less frequently mentioned are, however, the ultimate drivers of those immediate causes of biotic destruction, namely, human over population and continued population growth and over consumption. These drivers, all of which trace to the fiction that perpetual (economic) growth can occur on a finite planet, are themselves increasing rapidly.”

The final words of the report should send a chill down your spine “Thus we emphasise that the sixth mass extinction is already here and the window for effective action is very short, probably just two or three decades at most (more recent estimates are one to two decades if we start taking action immediately). All signs point to ever more powerful assaults on biodiversity in the next two decades, painting a dismal picture of the future of life, including human life.”

Article published in the Sunday Times of Malta, 5th May 2019