The next mass extinction

The Sixth Extinction – an Unnatural History by Elizabeth Kolbert published in 2014 by Bloomsbury at £17.99.

Reviewed by Alan Thornett


Elizabeth Kolbert is an American journalist and author, a staff writer on the New Yorker, with a strong commitment to the environment.

Elizabeth Kolbert’s new book, The Sixth Extinction – an Unnatural History, is a useful, well written, and accessible work. It is, however, a distressing read for those concerned with the impact of the human population on the ecology of the planet. This is because it sets out in stark terms the crisis of global biodiversity that has developed since the industrial revolution in particular, and how it continues to get worse at an alarming rate today.

She argues that from global warming alone (and there are myriad other factors involved), if it reaches its expected maximum by the middle of this century (and it could be worse than that), between 38 and 52 per cent of species ‘would be fated to disappear’. She argues that an extinction rate of this scale ultimately puts at risk all species on the planet, including, eventually, our own.

To put this in perspective she takes looks at 450 million years of geological history and reviews the five previous mass extinctions that are recognized to have taken place since complex animals emerged. (A mass extinction is generally recognised as an event involving a profound loss of biodiversity in a geologically insignificant amount of time.)

From this she concludes that we are now witnessing the sixth great extinction. And we are not just witnessing it, she reminds us, we are participants in it, and it’s about time we took the issue seriously.

She defines the previous mass extinction events as follows The End Ordovician Extinction, 450m years ago, the Late Devonian Extinction, 370m years ago. The End Permian Extinction, which was the most devastating and known as the mother of all extinctions, 225m years ago. The Late Triassic Extinction, 200m years ago, and the most recent, the End Cretaceous Extinction that took place around 60 m years ago that destroyed two thirds of all species at a stroke and saw the end of the dinosaurs.

The commonality of these previous extinctions, she argues, is that they were all the result of naturally occurring phenomena ranging from continental drift, glaciation, temperature change, chemical changes such as the acidification of the oceans, volcanic eruptions or earthquakes, or with the End Cretaceous the impact of a giant asteroid.

Today’s sixth extinction, she contends, is very different. It is, as she suggests in the title of the book, an ‘unnatural’ event. It has the magnitude of a mass extinction but this time it is not brought about by naturally occurring phenomena but as the direct result of the unwitting activity of one individual species on all the rest. This is the most intelligent, successful, and rapacious species the planet has produced—Homo sapiens, or modern human beings.

The term she uses for the current geological epoch therefore is the Anthropocene—or an epoch defined by the impact of human activity on the ecology of the planet.

This was coined by the ecologist Eugene Stoermer and supported by the Nobel Prize-winning atmospheric chemist Paul Cruzen, who argues that the impact of human activity on the earth’s ecology today is so significant as to constitute a new geological epoch. The term has not yet officially recognised by the scientific community, though Kolbert is confident that it will be.

She argues that since modern humans emerged 200,000 years ago, with their ingenuity, intellect, hunting skills, and drive to explore they have always had a disproportionate impact on other species. They were responsible for the demise of many of the large mammals that had no other predators but were vulnerable to modern humans. They were also, she argues, responsible for the demise of the Neanderthals, who lacked some of their key attributes.

She explains, how, much more recently, as maritime capability developed and colonial expansion started, sailors chomped their way though isolated and vulnerable species such as the dodo, the great auk, the giant tortoise, and flighted birds that had evolved with no fear of predation. The large, but slow moving, Steller’s sea cow was hunted to extinction. Such species went from abundance to extinction in very short periods of time.
It was not until the industrial revolution, however, and the arrival of capitalism of course (although that is not a factor that she draws attention to), that the full impact of modern humans was felt on the ecology and biodiversity of the planet—with the massive use of fossil fuels in particular. To research all this Kolbert travelled the world to meet scientists on the front line who are studying this process and trying to find some answers.
She visited the rain forest of the Manu National Park in the high Peruvian Andes, one of the planet’s biodiversity hot spots, to meet forest ecologist Miles Silman who was studying the effect of global warming by monitoring plants as they migrate up the mountain at rates of up to 100 feet a year in search of a higher, cooler, climate zone.

The conclusion Silman reaches is that global warming will not just affect biodiversity in the cold regions where the loss if ice, for example, is threatening those species that depend on it such as the polar bears and the ringed seal. It is also affecting, even more severely, the tropical regions where most species live.

She travelled to a 10 hector reserve (reserve 1202) in Amazonia to look at the impact of tropical deforestation and habitat fragmentation on the biodiversity crisis. She found that Reserve 1202 is a part of a patchwork such reserves (bits of rain forest) left behind for ‘conservation purposes’ after the loggers had cleared the bulk of the forest. She met researchers who were studying how the plants and animals deal with such isolation and how much protection such reserves provide.

The conclusions she came to were that such fragments provide little protection and that a conservative figure is that something like 5,000 species are being lost each year—or 14 species a day—in the tropical regions.

She visited the El Valle Amphibian Conservation Centre (EVACC) in Panama, which is dedicated to the survival of endangered amphibians, and linked up with its director Edgardo Griffiths for a scary look at what is happening to the planet’s amphibian population. She found that amphibians are not only the group of species that has managed to survive most successfully everything thing that the planet has thrown at them for hundreds of million years but they are now amongst the most endangered group of species—particularly over the past 40 years when their plight has become catastrophic.

Amphibians, she points out, are affected not only by habitat loss and general pollution but the spread of diseases and invasive species resulting from the globalization of travel and the mass transportation of goods that now reaches every corner of the planet. All this produces a figure that is it hard to grasp: that the extinction rate among amphibians could be a mind-boggling 45,000 times (yes 45,000) higher than the “background” rate—i.e. the rate that existed for millions of years before the current die off began.

The background rate of extinction varies with different species of course. With mammals this has been calculated to be about one every 700 years yet in the current event a quarter of all mammal species are at risk over just s few hundred years.

She went to Castello Aragonese, a tiny island about thirty kilometers west of Naples in order meet scientists studying the acidification of the oceans and to see under water carbon dioxide vents that render the sea around the island to a level of acidity that is already the fate of some parts of the oceans and could be the fate whole of the whole ocean if fossil fuels continue to be used at current rates.

She describes a scene where the organisms that rely on calcification for their shells or body structure are in big trouble. Barnacles are bleached white and the shells of the mussels, snails, and sea urchins are being dissolved by acidification small crustations have all but disappeared.

She points out that since the start of the industrial revolution humans have added some 365 billion metric tons of carbon into the atmosphere. Deforestation has added another nine billion tons. Each year this increases by another nine billion tons. This has increased the carbon in the atmosphere to over 400 parts per million and rising. This not only generates the warming of the atmosphere but since carbon dissolves readily into water it enters the oceans and creates acidification. Global warming is therefore a double whammy. Today, she observes, the oceans are absorbing around two and a half billion tons of additional carbon a year.

The oceans are already 30 times more acidic than they were in 1800 and at the current rate by the end of the century they will be 150 times more acidic than at the start of the industrial revolution. Here, she observes, there is a link to the past since ocean acidification played an important part in at least two of the previous two mass extinctions—at a time when all life was confined to the oceans.

She visited the tiny One Tree Island on the Great Barrier Reef to meet scientists from the University of Queensland who were studying the health of the coral reefs—and to witness the annual coral spawning. She discovered that the threat to coral reefs does not just come from acidification but also from overfishing, which promotes algae growth, deforestation and the resulting loss of water clarity, and dynamite fishing but most importantly from global warming.

Tropical reefs need warm seas but their temperature range is very narrow. Excessive heat disrupts their reproduction process and causes a condition called bleaching. She points out that there have been three major bleaching events in recent years—1998, 2005, and 2010—and that the frequency and intensity of such events are expected to increase as the global temperature climbs’.

She looks at the mass die-off of millions of bats in the Northeast of the USA as a result of a fungus transported around the world as a result of modern travel and trade. She looks at the imminent extinction of large and iconic species such as Suci the Sumatran rhino in Cincinnati Zoo, a member of a species on the very edge of extinction, who can’t ovulate unless she senses there is a male around who is ready to mate. And since the nearest male is 10,000 miles away Suci has a serious reproductive problem.

She looks at the problem of introduces and invasive species and concludes (remarkably) that at in any 24 hour period 10,00 different species are being moved around the world just in ballast water. She looks at the example of Hawaii where a new invasive species is added every month. In terms a species distribution she concludes that we are moving towards a situation where the world will be just one big continent.

There is an abundance of additional examples Elizabeth Kolbert could give to make her case. As I was writing this review there was news that barn owl numbers is Britain have reached a dangerous new low. But she has done more than enough, in my view, to make her case that we are living through the epoch of the Anthropocene.

She doesn’t offer any quick solutions or urge us to step up our campaigning activities in defence of the environment and of endangered species—although this is implicit in what she says, the people she meets, and how she presents them.

The book is an appeal for a greater awareness of what is going on. She urges us to think more deeply about our own role in the process: “If you want to think about why humans are so dangerous to other species, you can have a picture of a poacher in Africa carrying a AK-47 or a logger in the Amazon gripping an axe, or better still, you can picture yourself, holding a book on your lap.”

She also poses an important question. In an extinction event of our own making, she asks, what will happen to us? Her answer runs as follows: “having freed ourselves from the constraints of evolution, humans nevertheless remain dependent on the earth’s biological and geochemical systems. By disrupting these system—cutting down tropical rain forests, altering the composition of the atmosphere, acidifying the oceans—we’re putting our own survival in danger… When a mass extinction occurs, it takes out the weak, but it also lays low the strong.”

The advantage we have, she argues, is that whilst the damage done by modern humans was for most of the time unwitting it is no longer unwitting. We have the ability to take a new course, should we choose to do so, and its about time we discussed it seriously.

March 25th 2014

  1. No doubt talk of ‘A sixth extinction’ forces a critical eye on the nature of our civilization and the blame game begins. But what is self evident, is that every ‘ism’ and ‘ology’ have done nothing but keep our species on that slippery slope. And what choice exist between any political, religious or intellectual tradition, which the ability of the earth to sustain existence is under threat. When the problem is a limitation within human nature itself, the solution won’t come from us!

  2. I’ve yet to read Kolbert’s book, but this review gives a very good summary of the effects of global warming and neoliberal globalisation on biodiversity. I’m not sure I agree with Kolbert’s claim that, even at the very high rates of extinction that Alan recounts, all life on earth is under threat, but certainly larger, less adaptable organisms are. Human beings are particularly under threat, I think, because we depend on the continued functioning of so many different ecosystems (agriculture, but not only that) for our survival.

    I’m also not convinced that socialists should uncritically support the idea of using the term Anthropocene for this new geological epoch. I think it is right to differentiate between the mass extinctions carried out by human societies before and after the industrial revolution, a point after which it was possible to understand the kind of destruction capitalism was wreaking. This, I think, means the new epoch should be named after that economic system and not after “man (anthropos)” in general. This is what Murray Bookchin, one of the founders of “social ecology” said about apportioning the blame for ecological destruction to all people: “It preaches a gospel of a kind of ‘original sin’ that accuses a vague species called humanity—as though people of color were equatable with whites, women with men, the Third World with the First, the poor with the rich, and the exploited with their exploiters.”

    I don’t want to appear to be minimising the issue of ocean acidification, which is, after all one of the nine “ecological limits” that the system is in danger of transcending (or, in some cases, has already transcended), but the figure of “150 times more” acidity by the end of the century mentioned by Alan is a mistake. Kolbert talks about the ocean becoming “150 percent more acidic” than in 1800. This is a rather clumsy way of expressing the (very serious) problem, as the “150%” needs to be added to the pre-existing “100%”, so the “acidity” (more correctly, hydrogen ion concentration) will be 2.5 times the value in 1800. (If item B costs 100% more than item A, it means it costs twice as much). Here is a short article about ocean acidification:

  3. Yes. Alan Thornett’s words ring true, so I look forward to reading the book. As a freshwater ecologist turned environmentalist, now living in New Zealand, I’ve been aware of the loss of species for many, many years – local as well as total extinctions. My answer is to aid communication of environmental information – to speed it up but also to make it scientifically accurate and easy to analyse.
    There’s a problem – the Linnean System of naming and Classifying species is not good enough. My answer is to have a single, informal classified list of names! So, I’ve put one online at .
    It’s designed to leave the experts alone at the cutting edge of the research and just use the name that are in the books, reports and field guides – the ones that people are using. So, it starts with what is called the Year-version 2000 list for all species. Not all 1.9 million named species are listed (to do that, we need help to to form a not-for profit Trust and then organise crowd sourcing) so as to search and find them. But by searching for a Genus name you can add species names for all Flowering Plants and thus list them – so as to add your local, real-time species-related information into a checklist. Then edit it as a CSV-file, and send this around. All Families are listed for all Animals.
    Next there is an incomplete Year-version 2010. It contains all Genera of Flowering Plants with the APG classification – the one that uses the findings of DNA-work; a major revision! But maybe not the last.
    Maybe. I hope making environmental communications easier and faster will help more people get involved in adding a generation or more – hopefully many, many more, to the life-expectancy of our species.

  4. I think Alan Thornett’s review is excellent, and it delights me that SR is starting to have such a rich and diverse debate on biodiversity issues, with excellent comments, too, from Phil Ward.

    I think it is very important that we emphasise human (that is, us as a species) agency in this extinction event, as well as the current dominant agency of capitalism, both because the extinction event long antedates the birth of capitalism, and particularly because consumerism (in the imperialist countries) ties most of us in as agents in the destruction of nature and thus of our fouling of our own nest.

    Levels of woodland cover in England were not qualitatively different from those of modern capitalist Europe long before capitalism had started its ravages. Oliver Rackham (the woodland historian) writes that “half of England had ceased to be wildwood by 500 BC – or even earlier” – and that by Domesday Book (1086) only 15% was woodland, that is, less than France today (20%).

    By medieval times, too, most of the rich Mediterranean biota had been reduced to maquis, tillage and pasture, most of the middle east had lost its natural forest, wetland and grassland cover, and most of the big Asian floodplains and river valleys had, too. New Zealand was soon to lose its mega fauna to its Maori settlers. Australia had lost a large part of its mega fauna to its aboriginal hunters, and North America had long lost most of its mega fauna to its settler first peoples.

    Much of this ravaging of nature was PROGRESSIVE from the stance of us as a species (not a sin), because it increased our survival chances, as Oliver Rackham himself says.

    It has long since ceased to be so. It was a boon to assart ancient woodland in prehistoric and early historic England. It is an ethical crime, now.

    Alan Thornett is right to remind us that this extinction event is something which the UK suffers from, too. We are faced with appalling threats just to our small arboreal assemblage from imported diseases and parasites…to Ash of course, Oak, Alder, Beech, Pine, Larch, and many more familiar species. Extinctions begin with site extinctions, varietal and sub-species extinctions, and regional extinctions, long before they proceed to SPECIES and ecosystem extinctions.

    It is worth remembering, too, as a concern for socialist strategy, that the revolutionary overturnings that we all long for are themselves the cause of major losses to biodiversity. The Iranian revolution of 1979 caused the complete collapse of the systems of nature conservation that the Shah’s regime had latterly put in place, and that were having positive ameliorative results. The wildlands and the fauna and forests were simply pillaged in the following decades, and these disasters are only now beginning to be tentatively addressed. I dread to think of the catastrophe which the Syrian civil war has brought for its biota.

    As to the question of whether we are now in the ‘Anthropocene’, I tentatively side with Alan, though without much knowledge of how these periods are defined. If we can preside over an extinction event equal to the great past extinctions we can, I think, claim the right to name our own destruction after ourselves.

    Under the North Sea today the chalk is over 1300m thick, and it isn’t much thinner over much of south east England – all biologically created, for chalk is the excreta and corpses of 60 million years of tropical plankton. Over much of upland and northern England the coal measures and the limestones also have biological origins. How will this current extinction event affect the process – so much of which is biological in character – of geological deposition and attrition ?

    Here is a poem to finish,

    Dave Bangs

    My fossil chalk pit Lobster

    Lorries and cars, trains and vans
    Roar past, or chunder, halted for a jiffy.
    Lights at night. Noise always.

    Funny place to find a Lobster.

    Six miles southwards the real sea lies,
    With clanking dredgers and the
    Haul of fishing’s meagre pickings
    – A haul to scarcely fill a few
    Cold marble market slabs

    My Lobster’s a survivor.

    She’s survived
    She has !

    I see her in the cracked grey rock,
    Her near-eternal hidey-hole.
    I peer with eyeglass. Squint up close.

    I see her spines and pincers black
    Glossy and black as plain to see
    As though she’d died but yesterday,

    Not long before whole mountains reared –

    Whole mountain chains from plain and undersea
    That reared and groaned and raised their bulk
    In time i n f i n i t e s i m a l l y long,
    While she lay still within her chalky tomb.

    And now she lies within her broken home
    Cupped in my hand.

    I’m like a god, I think, to span such
    God-like numbing tracts of time
    In my mind-speeding wonder.


    Some gods we are !

    Who make our own sea empty
    And empty all the land
    Of life except our own.

    My Lobster’s owned more of eternity
    Than we will ever know.

  5. We do need to get past the stage of hand-wringing and awe-struck fear of the power that science and technology give to human beings to wreak havoc in nature. I’m bound to say that my impression from this review is that this book, for all its merits, does not achieve that. Without wishing to over-simplify the situation, I think the problem is much the same as Engels formulated it more than a hundred years ago: “at every step we are reminded that we by no means rule over nature like a conqueror over a foreign people, like someone standing outside nature – but that we, with flesh, blood and brain, belong to nature, and exist in its midst, and that all our mastery of it consists in the fact that we have the advantage over all other creatures of being able to learn its laws and apply them correctly.”
    It is both possible and necessary for the working class to meet the environmental challenges posed by the destructive effects of capitalism, but only by taking control of the system of production, so that it no longer operates by the blind, anarchic, and destructive laws of the market.
    I wrote on this question on my blog a couple of weeks ago, in relation to the centenary of the extinction of the passenger pigeon in North America:

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