The Sixth Extinction Quotes

Though it might be nice to imagine there once was a time when man lived in harmony with nature, it’s not clear that he ever really did.

A sign in the Hall of Biodiversity offers a quote from the Stanford ecologist Paul Ehrlich: IN PUSHING OTHER SPECIES TO EXTINCTION, HUMANITY IS BUSY SAWING OFF THE LIMB ON WHICH IT PERCHES.

To argue that the current extinction event could be averted if people just cared more and were willing to make more sacrifices is not wrong, exactly; still, it misses the point. It doesn’t much matter whether people care or don’t care. What matters is that people change the world. This capacity predates modernity,

Somewhere in our DNA must lie the key mutation (or, more probably, mutations) that set us apart—the mutations that make us the sort of creature that could wipe out its nearest relative, then dig up its bones and reassemble its genome.

The current extinction has its own novel cause: not an asteroid or a massive volcanic eruption but "one weedy species.

The anthropologist Richard Leakey has warned that “Homo sapiens might not only be the agent of the sixth extinction, but also risks being one of its victims.” A sign in the Hall of Biodiversity offers a quote from the Stanford ecologist Paul Ehrlich: IN PUSHING OTHER SPECIES TO EXTINCTION, HUMANITY IS BUSY SAWING OFF THE LIMB ON WHICH IT PERCHES.

One of the defining features of the Anthropocene is that the world is changing in ways that compel species to move, and another is that it’s changing in ways that create barriers—roads, clear-cuts, cities—that prevent them from doing so.

By burning through coal and oil deposits, humans are putting carbon back into the air that has been sequestered for tens—in most cases hundreds—of millions of years. In the process, we are running geologic history not only in reverse but at warp speed.

By transporting Asian species to North America, and North American species to Australia, and Australian species to Africa, and European species to Antarctica, we are, in effect, reassembling the world into one enormous supercontinent—what biologists sometimes refer to as the New Pangaea.

With the capacity to represent the world in signs and symbols comes the capacity to change it, which, as it happens, is also the capacity to destroy it. A tiny set of genetic variations divides us from the Neanderthals, but that has made all the difference.

Zalasiewicz is convinced that even a moderately competent stratigrapher will, at the distance of a hundred million years or so, be able to tell that something extraordinary happened at the moment in time that counts for us as today. This is the case even though a hundred million years from now, all that we consider to be the great works of man—the sculptures and the libraries, the monuments and the museums, the cities and the factories—will be compressed into a layer of sediment not much thicker than a cigarette paper.

There are so many things to be scared of in this world: blooms of jellies. A sixth extinction. A middle school dance. But maybe we can stop feeling so afraid. Maybe instead of feeling like a mote of dust, we can remember that all the creatures on this Earth are made from stardust. And we are the only ones who get to know it. That's the thing about jellyfish: They'll never understand that. All they can do is drift along, unaware. Humans may be newcomers to this planet. We may be plenty fragile. But we're also the only ones who can decide to change.

with the exception of humans, all the great apes today are facing oblivion.

The work is going well, but it looks like it might be the end of the world.”)

Nor does hardly anyone ever mention that we are in the midst of the sixth mass extinction, with about 200 species going extinct every single day.

One of the many unintended consequences of the Anthropocene has been the pruning of our own family tree. Having cut down our sister species—the Neanderthals and the Denisovans—many generations ago, we’re now working on our first and second cousins. By the time we’re done, it’s quite possible that there will be among the great apes not a single representative left, except, that is, for us.

Amphibians—the word comes from the Greek meaning ‘double life.

Even now, at least thirty thousand years after the fact, the signal is discernible: all non-Africans, from the New Guineans to the French to the Han Chinese, carry somewhere between one and four percent Neanderthal DNA.

having freed ourselves from the constraints of evolution, humans nevertheless remain dependent on the earth’s biological and geochemical systems. By disrupting these systems—cutting down tropical rainforests, altering the composition of the atmosphere, acidifying the oceans—we’re putting our own survival in danger.

We’re seeing right now that a mass extinction can be caused by human beings.

Obviously, the fate of our own species concerns us disproportionately. But at the risk of sounding anti-human—some of my best friends are humans!—I will say that it is not, in the end, what’s most worth attending to. Right now, in the amazing moment that to us counts as the present, we are deciding, without quite meaning to, which evolutionary pathways will remain open and which will forever be closed. No other creature has ever managed this, and it will, unfortunately, be our most enduring legacy. The Sixth Extinction will continue to determine the course of life long after everything people have written and painted and built has been ground into dust and giant rats have—or have not—inherited the earth.

Basically, if you were a triceratops in Alberta, you had about two minutes before you got vaporized” is how one geologist put it to me.

These days every wild place has, to one degree or another, been cut into and cut off.

It is estimated that one-third of all reef-building corals, a third of all freshwater mollusks, a third of sharks and rays, a quarter of all mammals, a fifth of all reptiles, and a sixth of all birds are headed toward oblivion.

In fact, the American Mastodon vanished around thirteen thousand years ago. Its demise was part of a wave of disappearances that has come to be known as the megafauna extinction. This wave coincided with the spread of modern humans and, increasingly, is understood to have been a result of it. In this sense, the crisis Cuvier discerned just beyond the edge of recorded history was us.

If climate change drove the megafauna extinct, then this presents yet another reason to worry about what we are doing to global temperatures. If, on the other hand, people were to blame—and it seems increasingly likely that they were—then the import is almost more disturbing. It would mean that the current extinction event began all the way back in the middle of the last ice age. It would mean that man was a killer—to use the term of art an “overkiller”—pretty much right from the start.

If warming were held to a minimum, the team estimated that between 22 and 31 percent of the species would be “committed to extinction” by 2050. If warming were to reach what was at that point considered a likely maximum—a figure that now looks too low—by the middle of this century, between 38 and 52 percent of the species would be fated to disappear.

In a similar vein, Jared Diamond has observed: “Personally, I can’t fathom why Australia’s giants should have survived innumerable droughts in their tens of millions of years of Australian history, and then have chosen to drop dead almost simultaneously (at least on a time scale of millions of years) precisely and just coincidentally when the first humans arrived.

Under what’s known as a “business as usual” emissions scenario, surface ocean pH will fall to 8.0 by the middle of this century, and it will drop to 7.8 by the century’s end. At that point, the oceans will be 150 percent more acidic than they were at the start of the industrial revolution.*

Of the world’s eight species of bears, six are categorized either as “vulnerable” to extinction or “endangered.

As a general rule, the variety of life is most impoverished at the poles and richest at low latitudes.

a single-continent world would be expected to contain only about a third as many mammalian species as currently exist.

When all of these were considered together, a pattern emerged: mass extinctions seemed to take place at regular intervals of roughly twenty-six million years.

Only in a place where the rules of the game remain fixed is there time for butterflies to evolve to feed on the shit of birds that evolved to follow ants.

the center of the American Museum of Natural History’s Hall of Biodiversity, there’s an exhibit embedded in the floor. The exhibit is arranged around a central plaque that notes there have been five major extinction events since complex animals evolved, over five hundred million years ago. According to the plaque, “Global climate change and other causes, probably including collisions between earth and extraterrestrial objects,” were responsible for these events. It goes on to observe: “Right now we are in the midst of the Sixth Extinction, this time caused solely by humanity’s transformation of the ecological landscape.

Eighty-five percent of recorded species live in the terrestrial realm, and the majority of these, some 850,000, are arthropods (that is, insects, spiders, and crustaceans). Most of the arthropod species are insects, and almost half of these are beetles, a fact that is said to have inspired a famous epigram from the British biologist J.B.S. Haldane. On being asked, one day, by some clerical gentlemen what his study of the natural world had revealed to him about God. Haldane is said to have replied that it indicated that He had "an inordinate fondness of beetles.

Until recently, when both of them went extinct, there were two species of frogs, known as gastric-brooding frogs, that carried their eggs in their stomachs and gave birth to little froglets through their mouths.

Our self-awareness impresses itself on us so cogently, as individuals and as a species, that we cannot imagine ourselves out of existence, even though for hundreds of millions of years humans played no part in the flow of life on the planet. When Teilhard de Chardin wrote, "The phenomenon of Man was essentially foreordained from the beginning," he was speaking from the depth of individual experience, which we all share, as much as from religious philosophy. Our inability to imagine a world without Homo sapiens has a profound impact on our view of ourselves; it becomes seductively easy to imagine that our evolution was inevitable. And inevitability gives meaning to life, because there is a deep security in believing that the way things are is the way they were meant to be.

Today, amphibians enjoy the dubious distinction of being the world’s most endangered class of animals; it’s been calculated that the group’s extinction rate could be as much as forty-five thousand times higher than the background rate.

Other calculations of his show that to keep pace with the present rate of temperature change, plants and animals would have to migrate poleward by thirty feet a day, and that a molecule of CO2 generated by burning fossil fuels will, in the course of its lifetime in the atmosphere, trap a hundred thousand times more heat

Unfortunately, the biggest tipping point, the one at which the ecosystem starts to crash, is mean pH 7.8, which is what we’re expecting to happen by 2100,” Hall-Spencer tells me, in his understated British manner. “So that is rather alarming.

Darwin’s theory about how species originated doubled as a theory of how they vanished. Extinction and evolution were to each other the warp and weft of life’s fabric, or, if you prefer, two sides of the same coin. “The appearance of new forms and the disappearance of old forms” were, Darwin wrote, “bound together.” Driving both was the “struggle for existence,” which rewarded the fit and eliminated the less so.

If we assume, very conservatively, that there are two million species in the tropical rainforests, this means that something like five thousand species are being lost each year. This comes to roughly fourteen species a day, or one every hundred minutes.

on Easter Island concluded that it wasn’t humans who deforested the landscape; rather, it was the rats

Don’t step on any dead bats.” It took me a moment to realize he was joking.

every year more non-indigenous species of mammals, birds, amphibians, turtles, lizards, and snakes are brought into the U.S. than the country has native species of these groups.

Assuming that humans continue to burn fossil fuels, the oceans will continue to absorb carbon dioxide and will become increasingly acidified.

within the next fifty years or so “all coral reefs will cease to grow and start to dissolve.

coral cover in the Caribbean has in recent decades declined by close to eighty percent.

given a shave and a new suit, the pair wrote, a Neanderthal probably would attract no more attention on a New York City subway “than some of its other denizens.

Where the kids routinely outscored the apes was in tasks that involved reading social cues.

Frogs had ruined his marriage.

At the heart of Darwin’s theory, as one of his biographers has put it, is “the denial of humanity’s special status.

Beginnings, it’s said, are apt to be shadowy.

Meanwhile, an even stranger and more radical transformation is under way. Having discovered subterranean reserves of energy, humans begin to change the composition of the atmosphere.

that a molecule of CO2 generated by burning fossil fuels will, in the course of its lifetime in the atmosphere, trap a hundred thousand times more heat than was released in producing it.

The current extinction has its own novel cause: not an asteroid or a massive volcanic eruption but "one weedy species". (...) We're seeing right now that a mass extinction can be caused by human beings.

It demonstrates, he has written, that humans "are capable of driving virtually any large mammal species extinct, even though they are also capable of going to great lengths to guarantee that they do not.

this will, in turn, trigger a variety of world-altering events, including the disappearance of most remaining glaciers, the inundation of low-lying islands and coastal cities, and the melting of the Arctic ice cap.

Birds are facing change on a scale unknown in their evolutionary history. This is a result of the Anthropocene—the new epoch of man-made change that is contributing to what has been called the sixth mass extinction.

Even with our immense wealth and technology, we continue to abuse the planet and each other for the sake of easy packaging and a cheap, disposable lifestyle. Unchecked population continues to outstrip the availability of housing, water, food, education, and jobs, while we squabble over politics, religion, gender, race, and nationality. Factor in the unrelenting advance of climate change, ocean acidification, the sixth extinction, the nuclear waste time bomb, ground water depletion, the social cancer of wealth inequality, dystopian surveillance, and the unstoppable US deficit growth and that’s a really bad news day for most of the planet during any age.

The bird that is shot is a parent,” he observed in an address to the British Association for the Advancement of Science. “We take advantage of its most sacred instincts to waylay it, and in depriving the parent of life, we doom the helpless offspring to the most miserable of deaths, that by hunger. If this is not cruelty, what is?

The way corals change the world—with huge construction projects spanning multiple generations—might be likened to the way that humans do, with this crucial difference. Instead of displacing other creatures, corals support them.

At the end of a mass extinction, the tree of life has lost several branches-and yet, afterward, life does go on. Plants regreen the earth and animals repopulate the oceans; different species relentless forward march. There will be life on planet Earth after the sixth mass extinction, but we are not able to imagine it any better than the dinosaurs could have imagined a world dominated by mammals walking on two legs, driving bulldozers, and flying airplanes.

From the standpoint of the world’s biota, global travel represents a radically new phenomenon and, at the same time, a replay of the very old. The drifting apart of the continents that Wegener deduced from the fossil record is now being reversed—another way in which humans are running geologic history backward and at high speed. Think of it as a souped-up version of plate tectonics, minus the plates. By transporting Asian species to North America, and North American species to Australia, and Australian species to Africa, and European species to Antarctica, we are, in effect, reassembling the world into one enormous supercontinent—what biologists sometimes refer to as the New Pangaea.

A group of scientists led by Bärbel Hönisch, of Columbia’s Lamont-Doherty Earth Observatory, recently reviewed the evidence for changing CO2 levels in the geologic past and concluded that, although there are several severe episodes of ocean acidification in the record, “no past event perfectly parallels” what is happening right now, owing to “the unprecedented rapidity of CO2 release currently taking place.” It turns out there just aren’t many ways to inject billions of tons of carbon into the air very quickly.

Archaic humans like Homo erectus “spread like many other mammals in the Old World,” Pääbo told me. “They never came to Madagascar, never to Australia. Neither did Neanderthals. It’s only fully modern humans who start this thing of venturing out on the ocean where you don’t see land. Part of that is technology, of course; you have to have ships to do it. But there is also, I like to think or say, some madness there. You know? How many people must have sailed out and vanished on the Pacific before you found Easter Island? I mean, it’s ridiculous. And why do you do that? Is it for the glory? For immortality? For curiosity? And now we go to Mars. We never stop.

In my lifelong study of the scores of species of ants to be found in the tropical forests of Dal Hon, I am led to the conviction that all forms of life are engaged in a struggle to survive, and that within each species there exists a range of natural but variable proclivities, of physical condition and of behaviour, which in turn weighs for or against in the battle to survive and procreate. Further, it is my suspicion that in the act of procreation, such traits are passed on. By extension, one can see that ill traits reduce the likelihood of both survival and procreation. On the basis of these notions, I wish to propose to my fellow scholars at this noble gathering a law of survival that pertains to all forms of life. But before I do so, I must add one more caveat, drawn from the undeniable behavioural characteristics of, in my instance of speciality, ants. To whit, success of one form of life more often than not initiates devastating population collapse among competitors, and indeed, sometimes outright extinction. And that such annihilation of rivals may in fact be a defining feature of success. Thus, my colleagues, I wish to propose a mode of operation among all forms of life, which I humbly call-in my four-volume treatise-‘The Betrayal of the Fittest’. Obsessional Scrolls Sixth Day Proceedings Address Of Skavat Gill Unta, Malazan Empire, 1097 Burn's Sleep

Everything (and everyone) alive today is descended from an organism that somehow survived the impact. But it does not follow from this that they (or we) are any better adapted. In times of extreme stress, the whole concept of fitness, at least in a Darwinian sense, loses its meaning: how could a creature be adapted, either well or ill, for conditions it has never before encountered in its entire evolutionary history?

If you count people as an invasive species—the science writer Alan Burdick has called Homo sapiens “arguably the most successful invader in biological history”—the process goes back a hundred and twenty thousand years or so, to the period when modern humans first migrated out of Africa.

• Human activity has transformed between a third and a half of the land surface of the planet. • Most of the world’s major rivers have been dammed or diverted. • Fertilizer plants produce more nitrogen than is fixed naturally by all terrestrial ecosystems. • Fisheries remove more than a third of the primary production of the oceans’ coastal waters. • Humans use more than half of the world’s readily accessible fresh water runoff.

WHY is ocean acidification so dangerous? The question is tough to answer only because the list of reasons is so long. Depending on how tightly organisms are able to regulate their internal chemistry, acidification may affect such basic processes as metabolism, enzyme activity, and protein function. Because it will

New York group that took as its mission “the introduction and acclimatization of such foreign varieties of the animal and vegetable kingdom as might prove useful or interesting” imported European starlings to the U.S. (The head of the group supposedly wanted to bring to America all the birds mentioned in Shakespeare.)

There is every reason to believe that if humans had not arrived on the scene, the Neanderthals would be there still, along with the wild horses and the woolly rhinos. With the capacity to represent the world in signs and symbols comes the capacity to change it, which, as it happens, is also the capacity to destroy it.

During any given twenty-four-hour period, it is estimated that ten thousand different species are being moved around the world just in ballast water. Thus a single supertanker (or, for that matter, a jet passenger) can undo millions of years of geographic separation. Anthony Ricciardi, a specialist in introduced species at McGill University, has dubbed the current reshuffling of the earth’s biota a “mass invasion event.” It is, he has written, “without precedent” in the planet’s history.

oceans’ surface waters has already dropped, from an average of around 8.2 to an average of around 8.1. Like the Richter scale, the pH scale is logarithmic, so even such a small numerical difference represents a very large real-world change. A decline of .1 means that the oceans are now thirty percent more acidic than they were in 1800.

The whole new layer on top of what I was thinking about in the nineteen-seventies is climate change,” Lovejoy told me. He has written that “in the face of climatic change, even natural climatic change, human activity has created an obstacle course for the dispersal of biodiversity,” the result of which could be “one of the greatest biotic crises of all time.

All are but parts of one stupendous whole, Whose body nature is, and God the soul.

the crisis Cuvier discerned just beyond the edge of recorded history was us.

The birds do not like this camera,” Sveinsson said. “So they fly over it and shit on it.

(The desolate post-impact sea has been dubbed the “Strangelove ocean.”)

It was titled “Helping a Species Go Extinct.

how to perform an ultrasound with one arm up a rhino’s rectum.

it has since been reduced to around five thousand animals.

background extinction.” In ordinary times—times here understood to mean whole geologic epochs—extinction takes place only very rarely, more rarely even than speciation, and it occurs at what’s known as the background extinction rate. This rate varies from one group of organisms to another; often it’s expressed in terms of extinctions per million species-years.

And if there were four extinct species, Cuvier declared, there must be others. The proposal was a daring one to make given the available evidence. On the basis of a few scattered bones, Cuvier had conceived of a whole new way of looking at life. Species died out. This was not an isolated but a widespread phenomenon. “All these facts, consistent among themselves, and not opposed by any report, seem to me to prove the existence of a world previous to ours,” Cuvier said. “But what was this primitive earth? And what revolution was able to wipe it out?

the planet has undergone change so wrenching that the diversity of life has plummeted. Five of these ancient events were catastrophic enough that they’re put in their own category: the so-called Big Five. In what seems like a fantastic coincidence, but is probably no coincidence at all, the history of these events is recovered just as people come to realize that they are causing another one.

Such is the economy of nature,” he wrote, “that no instance can be produced of her having permitted any one race of her animals to become extinct; of her having formed any link in her great work so weak as to be broken.

we can identify the causes of these revolutions, they’re highly varied: glaciation in the case of the end-Ordovician extinction, global warming and changes in ocean chemistry at the end of the Permian, an asteroid impact in the final seconds of the Cretaceous. The current extinction has its own novel cause: not an asteroid or a massive volcanic eruption but “one weedy species.” As Walter Alvarez put it to me, “We’re seeing right now that a mass extinction can be caused by human

We are told that rising CO2 levels will cause a “sixth mass extinction”—a species extinction so devastating that we literally won’t be able to live. Given that previous mass extinctions involved phenomena that blocked out massive amounts of light and warmth, like the giant asteroid that left a ninety-three-mile wide, twelve-mile-deep crater 66 million years ago in what is now Mexico, there is an incredibly high bar to claim that an increase in a warming and fertilizing gas will cause mass extinction.

In its magnitude, the temperature change projected for the coming century is roughly the same as the temperature swings of the ice ages. (If current emissions trends continue, the Andes are expected to warm by as much as nine degrees.) But if the magnitude of the change is similar, the rate is not, and, once again, rate is key. Warming today is taking place at least ten times faster than it did at the end of the last glaciation, and at the end of all those glaciations that preceded it. To keep up, organisms will have to migrate, or otherwise adapt, at least ten times more quickly.

SINCE the start of the industrial revolution, humans have burned through enough fossil fuels—coal, oil, and natural gas—to add some 365 billion metric tons of carbon to the atmosphere. Deforestation has contributed another 180 billion tons. Each year, we throw up another nine billion tons or so, an amount that’s been increasing by as much as six percent annually. As a result of all this, the concentration of carbon dioxide in the air today—a little over four hundred parts per million—is higher than at any other point in the last eight hundred thousand years. Quite probably it is higher than at any point in the last several million years. If current trends continue, CO2 concentrations will top five hundred parts per million, roughly double the levels they were in preindustrial days, by 2050. It is expected that such an increase will produce an eventual average global temperature rise of between three and a half and seven degrees Fahrenheit, and this will, in turn, trigger a variety of world-altering events, including the disappearance of most remaining glaciers, the inundation of low-lying islands and coastal cities, and the melting of the Arctic ice cap. But this is only half the story.

Crutzen wrote up his idea in a short essay, “Geology of Mankind,” that ran in Nature. “It seems appropriate to assign the term ‘Anthropocene’ to the present, in many ways human-dominated, geological epoch,” he observed. Among the many geologic-scale changes people have effected, Crutzen cited the following: • Human activity has transformed between a third and a half of the land surface of the planet. • Most of the world’s major rivers have been dammed or diverted. • Fertilizer plants produce more nitrogen than is fixed naturally by all terrestrial ecosystems. • Fisheries remove more than a third of the primary production of the oceans’ coastal waters. • Humans use more than half of the world’s readily accessible fresh water runoff. Most significantly, Crutzen said, people have altered the composition of the atmosphere. Owing to a combination of fossil fuel combustion and deforestation, the concentration of carbon dioxide in the air has risen by forty percent over the last two centuries, while the concentration of methane, an even more potent greenhouse gas, has more than doubled. “Because of these anthropogenic emissions,” Crutzen wrote, the global climate is likely to “depart significantly from natural behavior for many millennia to come.

The end-Permian extinction also seems to have been triggered by a change in the climate. But in this case, the change went in the opposite direction. Right at the time of extinction, 252 million years ago, there was a massive release of carbon into the air—so massive that geologists have a hard time even imagining where all the carbon could have come from. Temperatures soared—the seas warmed by as much as eighteen degrees—and the chemistry of the oceans went haywire, as if in an out-of-control aquarium. The water became acidified, and the amount of dissolved oxygen dropped so low that many organisms probably, in effect, suffocated.

Once the Funk Island birds had been salted, plucked, and deep-fried into oblivion, there was only one sizable colony of great auks left in the world, on an island called the Geirfuglasker, or great auk skerry, which lay about fifty kilometres off southwestern Iceland’s Reykjanes Peninsula. Much to the auk’s misfortune, a volcanic eruption destroyed the Geirfuglasker in 1830. This left the birds one solitary refuge, a speck of an island known as Eldey. By this point, the great auk was facing a new threat: its own rarity. Skins and eggs were avidly sought by gentlemen, like Count Raben, who wanted to fill out their collections. It was in the service of such enthusiasts that the very last known pair of auks was killed on Eldey in 1844.

Today, amphibians enjoy the dubious distinction of being the world’s most endangered class of animals; it’s been calculated that the group’s extinction rate could be as much as forty-five thousand times higher than the background rate. But extinction rates among many other groups are approaching amphibian levels. It is estimated that one-third of all reef-building corals, a third of all freshwater mollusks, a third of sharks and rays, a quarter of all mammals, a fifth of all reptiles, and a sixth of all birds are headed toward oblivion. The losses are occurring all over: in the South Pacific and in the North Atlantic, in the Arctic and the Sahel, in lakes and on islands, on mountaintops and in valleys. If you know how to look, you can probably find signs of the current extinction event in your own backyard.

Ocean acidification is sometimes referred to as global warming’s “equally evil twin.” The irony is intentional and fair enough as far as it goes, which may not be far enough. No single mechanism explains all the mass extinctions in the record, and yet changes in ocean chemistry seem to be a pretty good predictor. Ocean acidification played a role in at least two of the Big Five extinctions (the end-Permian and the end-Triassic) and quite possibly it was a major factor in a third (the end-Cretaceous). There’s strong evidence for ocean acidification during an extinction event known as the Toarcian Turnover, which occurred 183 million years ago, in the early Jurassic, and similar evidence at the end of the Paleocene, 55 million years ago, when several forms of marine life suffered a major crisis. “Oh, ocean acidification,” Zalasiewicz had told me at Dob’s Linn. “That’s the big nasty one that’s coming down.

Recent studies funded by Britain’s Natural Environment Research Council provide support for those concerns. (Thomas, et al, 2004; Stevens, et al, 2004) While there have been five mass extinctions in the history of our planet, they are all presumed to have been caused by extraterrestrial events, such as a comet smashing to earth. One of the new studies concludes that the “natural world is experiencing the sixth, major extinction event in its history.” (Lovell 2004) This time though, the cause of the extinction is not extraterrestrial. According to one of the study’s authors, Jeremy Thomas, “As far as we can tell this one is caused by one animal organism—man.

Life, in short, just wants to be. But—and here’s an interesting point—for the most part it doesn’t want to be much. This is perhaps a little odd because life has had plenty of time to develop ambitions. If you imagine the 4.5 billion odd years of Earth’s history compressed into a normal earthly day, then life begins very early, about 4 A.M., with the rise of the first simple, single-celled organisms, but then advances no further for the next sixteen hours. Not until almost 8:30 in the evening, with the day five-sixths over, has Earth anything to show the universe but a restless skin of microbes. Then, finally, the first sea plants appear, followed twenty minutes later by the first jellyfish and the enigmatic Ediacaran fauna first seen by Reginald Sprigg in Australia. At 9:04 P.M. trilobites swim onto the scene, followed more or less immediately by the shapely creatures of the Burgess Shale. Just before 10 P.M. plants begin to pop up on the land. Soon after, with less than two hours left in the day, the first land creatures follow. Thanks to ten minutes or so of balmy weather, by 10:24 the Earth is covered in the great carboniferous forests whose residues give us all our coal, and the first winged insects are evident. Dinosaurs plod onto the scene just before 11 P.M. and hold sway for about three-quarters of an hour. At twenty-one minutes to midnight they vanish and the age of mammals begins. Humans emerge one minute and seventeen seconds before midnight. The whole of our recorded history, on this scale, would be no more than a few seconds, a single human lifetime barely an instant. Throughout this greatly speeded-up day continents slide about and bang together at a clip that seems positively reckless. Mountains rise and melt away, ocean basins come and go, ice sheets advance and withdraw. And throughout the whole, about three times every minute, somewhere on the planet there is a flashbulb pop of light marking the impact of a Manson-sized meteor or one even larger. It’s a wonder that anything at all can survive in such a pummeled and unsettled environment. In fact, not many things do for long. Perhaps an even more effective way of grasping our extreme recentness as a part of this 4.5-billion-year-old picture is to stretch your arms to their fullest extent and imagine that width as the entire history of the Earth. On this scale, according to John McPhee in Basin and Range, the distance from the fingertips of one hand to the wrist of the other is Precambrian. All of complex life is in one hand, “and in a single stroke with a medium-grained nail file you could eradicate human history.” Fortunately, that moment hasn’t happened, but the chances are good that it will. I don’t wish to interject a note of gloom just at this point, but the fact is that there is one other extremely pertinent quality about life on Earth: it goes extinct. Quite regularly. For all the trouble they take to assemble and preserve themselves, species crumple and die remarkably routinely. And the more complex they get, the more quickly they appear to go extinct. Which is perhaps one reason why so much of life isn’t terribly ambitious.

Ocean Acidification is sometimes referred to as Global Warming's Equally Evil Twin. The irony is intentional and fair enough as far as it goes... No single mechanism explains all the mass extinctions in the record and yet changes in ocean chemistry seem to be a pretty good predictor. Ocean Acidification played a role in at least 2 of the Big Five Extinctions: the End-Permian and the End-Triassic. And quite possibly it was a major factor in a third, the End-Cretaceous. ...Why is ocean acidification so dangerous? The question is tough to answer only because the list of reasons is so long. Depending on how tightly organisms are able to regulate their internal chemistry, acidification may affect such basic processes as metabolism, enzyme activity, and protein function. Because it will change the makeup of microbial communities, it will alter the availability of key nutrients, like iron and nitrogen. For similar reasons, it will change the amount of light that passes through the water, and for somewhat different reasons, it will alter the way sound propagates. (In general, acidification is expected to make the seas noisier.) It seems likely to promote the growth of toxic algae. It will impact photosynthesis—many plant species are apt to benefit from elevated CO2 levels—and it will alter the compounds formed by dissolved metals, in some cases in ways that could be poisonous. Of the myriad possible impacts, probably the most significant involves the group of creatures known as calcifiers. (The term calcifier applies to any organism that builds a shell or external skeleton or, in the case of plants, a kind of internal scaffolding out of the mineral calcium carbonate.)... Ocean acidification increases the cost of calcification by reducing the number of carbonate ions available to organisms that build shells or exoskeletons. Imagine trying to build a house while someone keeps stealing your bricks. The more acidified the water, the greater the energy that’s required to complete the necessary steps. At a certain point, the water becomes positively corrosive, and solid calcium carbonate begins to dissolve. This is why the limpets that wander too close to the vents at Castello Aragonese end up with holes in their shells. According to geologists who work in the area, the vents have been spewing carbon dioxide for at least several hundred years, maybe longer. Any mussel or barnacle or keel worm that can adapt to lower pH in a time frame of centuries presumably already would have done so. “You give them generations on generations to survive in these conditions, and yet they’re not there,” Hall-Spencer observed.