Extinctions at record levels – 04/30/2007

  • November 30, 2013 at 6:43 pm #1493

    from rocky:

    Animal Extinction – the greatest threat to mankind
    By the end of the century half of all species will be extinct. Does that
    By Julia Whitty
    Published: 30 April 2007

    In the final stages of dehydration the body shrinks, robbing youth from
    the young as the skin puckers, eyes recede into orbits, and the tongue
    swells and cracks. Brain cells shrivel and muscles seize. The kidneys
    shut down. Blood volume drops, triggering hypovolemic shock, with its
    attendant respiratory and cardiac failures. These combined assaults
    disrupt the chemical and electrical pathways of the body until all
    systems cascade toward death.

    Such is also the path of a dying species. Beyond a critical point, the
    collective body of a unique kind of mammal or bird or amphibian or tree
    cannot be salvaged, no matter the first aid rendered. Too few
    individuals spread too far apart, or too genetically weakened, are
    susceptible to even small natural disasters: a passing thunderstorm; an
    unexpected freeze; drought. At fewer than 50 members, populations
    experience increasingly random fluctuations until a kind of fatal
    arrhythmia takes hold. Eventually, an entire genetic legacy, born in the
    beginnings of life on earth, is removed from the future.

    Scientists recognise that species continually disappear at a background
    extinction rate estimated at about one species per million per year,
    with new species replacing the lost in a sustainable fashion. Occasional
    mass extinctions convulse this orderly norm, followed by excruciatingly
    slow recoveries as new species emerge from the remaining gene-pool,
    until the world is once again repopulated by a different catalogue of
    flora and fauna.

    From what we understand so far, five great extinction events have
    reshaped earth in cataclysmic ways in the past 439 million years, each
    one wiping out between 50 and 95 per cent of the life of the day,
    including the dominant life forms; the most recent event killing off the
    non-avian dinosaurs. Speciations followed, but an analysis published in
    Nature showed that it takes 10 million years before biological diversity
    even begins to approach what existed before a die-off.

    Today we’re living through the sixth great extinction, sometimes known
    as the Holocene extinction event. We carried its seeds with us 50,000
    years ago as we migrated beyond Africa with Stone Age blades, darts, and
    harpoons, entering pristine Ice Age ecosystems and changing them forever
    by wiping out at least some of the unique megafauna of the times,
    including, perhaps, the sabre-toothed cats and woolly mammoths. When the
    ice retreated, we terminated the long and biologically rich epoch
    sometimes called the Edenic period with assaults from our newest
    weapons: hoes, scythes, cattle, goats, and pigs.

    But, as harmful as our forebears may have been, nothing compares to
    what’s under way today. Throughout the 20th century the causes of
    extinction – habitat degradation, overexploitation, agricultural
    monocultures, human-borne invasive species, human-induced
    climate-change – increased exponentially, until now in the 21st century
    the rate is nothing short of explosive. The World Conservation Union’s
    Red List – a database measuring the global status of Earth’s 1.5 million
    scientifically named species – tells a haunting tale of unchecked,
    unaddressed, and accelerating biocide.

    When we hear of extinction, most of us think of the plight of the rhino,
    tiger, panda or blue whale. But these sad sagas are only small pieces of
    the extinction puzzle. The overall numbers are terrifying. Of the 40,168
    species that the 10,000 scientists in the World Conservation Union have
    assessed, one in four mammals, one in eight birds, one in three
    amphibians, one in three conifers and other gymnosperms are at risk of
    extinction. The peril faced by other classes of organisms is less
    thoroughly analysed, but fully 40 per cent of the examined species of
    planet earth are in danger, including perhaps 51 per cent of reptiles,
    52 per cent of insects, and 73 per cent of flowering plants.

    By the most conservative measure – based on the last century’s recorded
    extinctions – the current rate of extinction is 100 times the background
    rate. But the eminent Harvard biologist Edward O Wilson, and other
    scientists, estimate that the true rate is more like 1,000 to 10,000
    times the background rate. The actual annual sum is only an educated
    guess, because no scientist believes that the tally of life ends at the
    1.5 million species already discovered; estimates range as high as 100
    million species on earth, with 10 million as the median guess. Bracketed
    between best- and worst-case scenarios, then, somewhere between 2.7 and
    270 species are erased from existence every day. Including today.

    We now understand that the majority of life on Earth has never been –
    and will never be – known to us. In a staggering forecast, Wilson
    predicts that our present course will lead to the extinction of half of
    all plant and animal species by 2100.

    You probably had no idea. Few do. A poll by the American Museum of
    Natural History finds that seven in 10 biologists believe that mass
    extinction poses a colossal threat to human existence, a more serious
    environmental problem than even its contributor, global warming; and
    that the dangers of mass extinction are woefully underestimated by
    almost everyone outside science. In the 200 years since French
    naturalist Georges Cuvier first floated the concept of extinction, after
    examining fossil bones and concluding “the existence of a world previous
    to ours, destroyed by some sort of catastrophe”, we have only slowly
    recognised and attempted to correct our own catastrophic behaviour.

    Some nations move more slowly than others. In 1992, an international
    summit produced a treaty called the Convention on Biological Diversity
    that was subsequently ratified by 190 nations – all except the unlikely
    coalition of the United States, Iraq, the Vatican, Somalia, Andorra and
    Brunei. The European Union later called on the world to arrest the
    decline of species and ecosystems by 2010. Last year, worried
    biodiversity experts called for the establishment of a scientific body
    akin to the Intergovernmental Panel on Climate Change to provide a
    united voice on the extinction crisis and urge governments to action.

    Yet, despite these efforts, the Red List, updated every two years,
    continues to show metastatic growth. There are a few heartening examples
    of so-called Lazarus species lost and then found: the wollemi pine and
    the mahogany glider in Australia, the Jerdon’s courser in India, the
    takahe in New Zealand, and, maybe, the ivory-billed woodpecker in the
    United States. But for virtually all others, the Red List is a dry
    country with little hope of rain, as species ratchet down the listings
    from secure to vulnerable, to endangered, to critically endangered, to

    All these disappearing species are part of a fragile membrane of
    organisms wrapped around the Earth so thinly, writes Wilson, that it
    “cannot be seen edgewise from a space shuttle, yet so internally complex
    that most species composing it remain undiscovered”. We owe everything
    to this membrane of life. Literally everything. The air we breathe. The
    food we eat. The materials of our homes, clothes, books, computers,
    medicines. Goods and services that we can’t even imagine we’ll someday
    need will come from species we have yet to identify. The proverbial cure
    for cancer. The genetic fountain of youth. Immortality. Mortality. The
    living membrane we so recklessly destroy is existence itself.

    Biodiversity is defined as the sum of an area’s genes (the building
    blocks of inheritance), species (organisms that can interbreed), and
    ecosystems (amalgamations of species in their geological and chemical
    landscapes). The richer an area’s biodiversity, the tougher its immune
    system, since biodiversity includes not only the number of species but
    also the number of individuals within that species, and all the inherent
    genetic variations – life’s only army against the diseases of oblivion.

    Yet it’s a mistake to think that critical genetic pools exist only in
    the gaudy show of the coral reefs, or the cacophony of the rainforest.
    Although a hallmark of the desert is the sparseness of its garden, the
    orderly progression of plants and the understated camouflage of its
    animals, this is only an illusion. Turn the desert inside out and upside
    down and you’ll discover its true nature. Escaping drought and heat,
    life goes underground in a tangled overexuberance of roots and burrows
    reminiscent of a rainforest canopy, competing for moisture, not light.
    Animal trails criss-cross this subterranean realm in private burrows
    engineered, inhabited, stolen, shared and fought over by ants, beetles,
    wasps, cicadas, tarantulas, spiders, lizards, snakes, mice, squirrels,
    rats, foxes, tortoises, badgers and coyotes.

    To survive the heat and drought, desert life pioneers ingenious
    solutions. Coyotes dig and maintain wells in arroyos, probing deep for
    water. White-winged doves use their bodies as canteens, drinking enough
    when the opportunity arises to increase their bodyweight by more than 15
    per cent. Black-tailed jack rabbits tolerate internal temperatures of
    111F. Western box turtles store water in their oversized bladders and
    urinate on themselves to stay cool. Mesquite grows taproots more than
    160ft deep in search of moisture.

    These life-forms and their life strategies compose what we might think
    of as the “body” of the desert, with some species the lungs and others
    the liver, the blood, the skin. The trend in scientific investigation in
    recent decades has been toward understanding the interconnectedness of
    the bodily components, i.e. the effect one species has on the others.
    The loss of even one species irrevocably changes the desert (or the
    tundra, rainforest, prairie, coastal estuary, coral reef, and so on) as
    we know it, just as the loss of each human being changes his or her
    family forever.

    Nowhere is this better proven than in a 12-year study conducted in the
    Chihuahuan desert by James H Brown and Edward Heske of the University of
    New Mexico. When a kangaroo-rat guild composed of three closely related
    species was removed, shrublands quickly converted to grasslands, which
    supported fewer annual plants, which in turn supported fewer birds. Even
    humble players mediate stability. So when you and I hear of this year’s
    extinction of the Yangtze river dolphin, and think, “how sad”, we’re not
    calculating the deepest cost: that extinctions lead to co-extinctions
    because most living things on Earth support a few symbionts, while
    keystone species influence and support myriad plants and animals. Army
    ants, for example, are known to support 100 known species, from beetles
    to birds. A European study finds steep declines in honeybee diversity in
    the past 25 years but also significant attendant declines in plants that
    depend on bees for pollination – a job estimated to be worth £50bn
    worldwide. Meanwhile, beekeepers in 24 American states report that
    perhaps 70 per cent of their colonies have recently died off,
    threatening £7bn in US agriculture. And bees are only a small part of
    the pollinator crisis.

    One of the most alarming developments is the rapid decline not just of
    species but of higher taxa, such as the class Amphibia, the
    300-million-year-old group of frogs, salamanders, newts and toads hardy
    enough to have preceded and then outlived most dinosaurs. Biologists
    first noticed die-offs two decades ago, and, since then, have watched as
    seemingly robust amphibian species vanished in as little as six months.
    The causes cover the spectrum of human environmental assaults, including
    rising ultraviolet radiation from a thinning ozone layer, increases in
    pollutants and pesticides, habitat loss from agriculture and
    urbanisation, invasions of exotic species, the wildlife trade, light
    pollution, and fungal diseases. Sometimes stressors merge to form an
    unwholesome synergy; an African frog brought to the West in the 1950s
    for use in human pregnancy tests likely introduced a fungus deadly to
    native frogs. Meanwhile, a recent analysis in Nature estimated that, in
    the past 20 years, at least 70 species of South American frogs had gone
    extinct as a result of climate change.

    In a 2004 analysis published in Science, Lian Pin Koh and his colleagues
    predict that an initially modest co-extinction rate will climb
    alarmingly as host extinctions rise in the near future. Graphed out, the
    forecast mirrors the rising curve of an infectious disease, with the
    human species acting all the parts: the pathogen, the vector, the
    Typhoid Mary who refuses culpability, and, ultimately, one of up to 100
    million victims.

    “Rewilding” is bigger, broader, and bolder than humans have thought
    before. Many conservation biologists believe it’s our best hope for
    arresting the sixth great extinction. Wilson calls it “mainstream
    conservation writ large for future generations”. This is because more of
    what we’ve done until now – protecting pretty landscapes, attempts at
    sustainable development, community-based conservation and ecosystem
    management – will not preserve biodiversity through the critical next
    century. By then, half of all species will be lost, by Wilson’s

    To save Earth’s living membrane, we must put its shattered pieces back
    together. Only “megapreserves” modelled on a deep scientific
    understanding of continent-wide ecosystem needs hold that promise. “What
    I have been preparing to say is this,” wrote Thoreau more than 150 years
    ago. “In wildness is the preservation of the world.” This, science
    finally understands.

    The Wildlands Project, the conservation group spearheading the drive to
    rewild North America – by reconnecting remaining wildernesses (parks,
    refuges, national forests, and local land trust holdings) through
    corridors – calls for reconnecting wild North America in four broad
    “megalinkages”: along the Rocky Mountain spine of the continent from
    Alaska to Mexico; across the arctic/boreal from Alaska to Labrador;
    along the Atlantic via the Appalachians; and along the Pacific via the
    Sierra Nevada into the Baja peninsula. Within each megalinkage, core
    protected areas would be connected by mosaics of public and private
    lands providing safe passage for wildlife to travel freely. Broad,
    vegetated overpasses would link wilderness areas split by roads. Private
    landowners would be enticed to either donate land or adopt policies of
    good stewardship along critical pathways.

    It’s a radical vision, one the Wildlands Project expects will take 100
    years or more to complete, and one that has won the project a special
    enmity from those who view environmentalists with suspicion. Yet the
    core brainchild of the Wildlands Project – that true conservation must
    happen on an ecosystem-wide scale – is now widely accepted. Many
    conservation organisations are already collaborating on the project,
    including international players such as Naturalia in Mexico, US national
    heavyweights like Defenders of Wildlife, and regional experts from the
    Southern Rockies Ecosystem Project to the Grand Canyon Wildlands
    Council. Kim Vacariu, the South-west director of the US’s Wildlands
    Project, reports that ranchers are coming round, one town meeting at a
    time, and that there is interest, if not yet support, from the insurance
    industry and others who “face the reality of car-wildlife collisions

    At its heart, rewilding is based on living with the monster under the
    bed, since the big, scary animals that frightened us in childhood, and
    still do, are the fierce guardians of biodiversity. Without wolves,
    wolverines, grizzlies, black bears, mountain lions and jaguars, wild
    populations shift toward the herbivores, who proceed to eat plants into
    extinction, taking birds, bees, reptiles, amphibians and rodents with
    them. A tenet of ecology states that the world is green because
    carnivores eat herbivores. Yet the big carnivores continue to die out
    because we fear and hunt them and because they need more room than we
    preserve and connect. Male wolverines, for instance, can possess home
    ranges of 600 sq m. Translated, Greater London would have room for only

    The first campaign out of the Wildlands Project’s starting gate is the
    “spine of the continent”, along the mountains from Alaska to Mexico,
    today fractured by roads, logging, oil and gas development, grazing, ski
    resorts, motorised back-country recreation and sprawl.

    The spine already contains dozens of core wildlands, including
    wilderness areas, national parks, national monuments, wildlife refuges,
    and private holdings. On the map, these scattered fragments look like
    debris falls from meteorite strikes. Some are already partially buffered
    by surrounding protected areas such as national forests. But all need
    interconnecting linkages across public and private lands – farms,
    ranches, suburbia – to facilitate the travels of big carnivores and the
    net of biodiversity that they tow behind them.

    The Wildlands Project has also identified the five most critically
    endangered wildlife linkages along the spine, each associated with a
    keystone species. Grizzlies already pinched at Crowsnest Pass on Highway
    Three, between Alberta and British Columbia, will be entirely cut off
    from the bigger gene pool to the north if a larger road is built.
    Greater sage grouse, Canada lynx, black bears and jaguars face their own
    lethal obstacles further south.

    But by far the most endangered wildlife-linkage is the borderland
    between the US and Mexico. The Sky Islands straddle this boundary, and
    some of North America’s most threatened wildlife – jaguars, bison,
    Sonoran pronghorn, Mexican wolves – cross, or need to cross, here in the
    course of their life’s travels. Unfortunately for wildlife, Mexican
    workers cross here too. Men, women, and children, running at night,
    one-gallon water jugs in hand.

    The problem for wildlife is not so much the intrusions of illegal
    Mexican workers but the 700-mile border fence proposed to keep them out.
    From an ecological perspective, it will sever the spine at the lumbar,
    paralysing the lower continent.

    Here, in a nutshell, is all that’s wrong with our treatment of nature.
    Amid all the moral, practical, and legal issues with the border fence,
    the biological catastrophe has barely been noted. It’s as if extinction
    is not contagious and we won’t catch it.

    If, as some indigenous people believe, the jaguar was sent to the world
    to test the will and integrity of human beings, then surely we need to
    reassess. Border fences have terrible consequences. One between India
    and Pakistan forces starving bears and leopards, which can no longer
    traverse their feeding territories, to attack villagers.

    The truth is that wilderness is more dangerous to us caged than free –
    and has far more value to us wild than consumed. Wilson suggests the
    time has come to rename the “environmentalist view” the “real-world
    view”, and to replace the gross national product with the more
    comprehensive “genuine progress indicator”, which estimates the true
    environmental costs of farming, fishing, grazing, mining, smelting,
    driving, flying, building, paving, computing, medicating and so on.
    Until then, it’s like keeping a ledger recording income but not
    expenses. Like us, the Earth has a finite budget.

    Reprinted with permission from Mother Jones magazine. © 2007, Foundation
    for National Progress. The Fragile Edge: Diving and Other Adventures in
    the South Pacific by Julia Whitty is published by Houghton Mifflin on 7

    Disappearing World

    More than 16,000 species of the world’s mammals, birds, plants and other
    organisms are at present officially regarded as threatened with
    extinction to one degree or another, according to the Red List.

    Maintained by the Swiss-based World Conservation Union (usually known by
    the initials IUCN), the Red List is one of the gloomiest books in the
    world, and is set to get even gloomier.

    Since 1963 it has attempted to set out the conservation status of the
    planet’s wildlife, in a series of categories which now range from
    Extinct (naturally), through Critically Endangered, Endangered,
    Vulnerable and Near-Threatened, and finishing with Least Concern. The
    numbers in the “threatened” categories are steadily rising.

    Taxonomists at the IUCN regularly attempt to update the list, but that
    is a massive job to undertake – there are about 5,000 mammal species in
    the world and about 10,000 birds, but more than 300,000 types of plant,
    and undoubtedly well over a million insect species, and perhaps many
    more. Some species, such as beetles living in the rainforest canopy,
    could become extinct before they are even known to science.

    The last Red List update, released in May last year, looked at 40,168
    species and considered 16,118 to be threatened – including 7,725 animals
    of all types (mammals, birds, reptiles, fish, insects etc) and 8,390


    What has happened to the bees? What will be the consequences?

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