The Sixth Extinction

Images in this archived article have been removed.

Hope is the thing with feathers
That perches in the soul,
And sings the tune–without the words,
And never stops at all
— Emily Dickinson

Hope is a duty from which paleontologists are exempt…. If hope is the thing with feathers, as Emily Dickinson said, then it’s good to remember that feathers don’t generally fossilize well. In lieu of hope and despair, paleontologists have a highly developed sense of cyclicity. That’s why I recently went to Chicago, with a handful of urgently grim questions, and called on a paleontologist named David Jablonski. I wanted answers unvarnished with obligatory hope.
— David Quammen

Occasionally I am asked what I think the future will look like, not just in the next few years or in 10 years, but several decades from now. Frankly, it’s hard not to cringe, because my honest appraisal is not likely to be met with much enthusiasm. Some people harangue me via e-mail, asking why I don’t write about over-population and other great disasters. Well, I write for the association for the study of peak oil & natural gas, so I usually confine myself to energy supply & consumption, alternatives to fossil fuels, and economic or scientific issues that bear on these subjects.

I’ve been accused of being ignorant of, or not caring about, the Big Planetary Issues. Today I depart from my usual stuff, not just to answer a few critics, but more importantly to put our current energy & economic problems in proper perspective.

If the 20th century was a time of expansion and growth for human population and economies, the 21st century will surely usher in a peak and decline in both. Today I talk about my “favorite” disaster, called The Sixth Extinction. Even in the age of politically correct environmentalism, most people could care less about the Earth’s plant & animal species unless their decline bears directly and immediately on their own welfare. Accordingly, I will talk about some clear-cut examples where the health of the natural world adversely affects our future survival.

Before I talk about that, I want to touch on what I call, for lack of a better term, friedmanism.

I am referring to Tom Friedman, the influential Op/Ed columnist for the New York Times. I want to make it clear before I proceed that I am not launching a personal, ad hominem attack on Mr. Friedman. I’m sure he’s a nice guy, sincere and well-meaning. However, he exemplifies an all-too-common way of thinking about the Big Planetary Issues that virtually guarantees that they will not get fixed.

Tom Friedman was zeroing in on Reality in his March 7th column The Inflection Is Near? but the Awful Truth was too much for him to handle.

“We created a way of raising standards of living that we can’t possibly pass on to our children,” said Joe Romm, a physicist and climate expert who writes the indispensable blog climateprogress.org. We have been getting rich by depleting all our natural stocks — water, hydrocarbons, forests, rivers, fish and arable land — and not by generating renewable flows…

Over a billion people today suffer from water scarcity; deforestation in the tropics destroys an area the size of Greece every year — more than 25 million acres; more than half of the world’s fisheries are over-fished or fished at their limit…

One of those who has been warning me of this for a long time is Paul Gilding, the Australian environmental business expert. He has a name for this moment — when both Mother Nature and Father Greed have hit the wall at once — “The Great Disruption.”

“We are taking a system operating past its capacity and driving it faster and harder,” he wrote me. “No matter how wonderful the system is, the laws of physics and biology still apply.” We must have growth, but we must grow in a different way. For starters, economies need to transition to the concept of net-zero, whereby buildings, cars, factories and homes are designed not only to generate as much energy as they use but to be infinitely recyclable in as many parts as possible. Let’s grow by creating flows rather than plundering more stocks.

Gilding says he’s actually an optimist. So am I. People are already using this economic slowdown to retool and reorient economies. Germany, Britain, China and the U.S. have all used stimulus bills to make huge new investments in clean power. South Korea’s new national paradigm for development is called: “Low carbon, green growth”…

I eagerly await the day when the Laws of Thermodynamics have been repealed, a happier time to come when “net-zero” aluminum smelting generates as much energy as it consumes and Nissan Pathfinders have become perpetual motion machines. But let’s examine why, aside from being uninformed about physics, Friedman is optimistic. The short answer is: he’s got to be! Friedman has to be a “blue skies” kind of guy if he wants to be a mover and shaker, and a fixture at the New York Times. The alternative is quite literally unthinkable. What football coach, on the eve of the Super Bowl, would sincerely respond like this to a question about his team’s chances in the big game?

That other team’s pretty good… they’re favored by 3 touchdowns, and for good reason… I don’t think we can win this game, my guys are already whipped…. Honestly, we can’t compete with them physically, that’s the problem. We’ve got no shot.

This realistic coach would be fired in a heartbeat. A good football coach rallies his team, even if things look grim. But nothing important is riding on the outcome of a football game.

Tom Friedman’s job is to rally the Human Team, to make us all feel good about ourselves and our prospects. Cheerleading is deemed essential to leadership. Ben Bernanke did not think “the national housing boom is a bubble that is about to burst” in 2005. He was sticking to his story in 2007, long after house prices took a nosedive. Here’s another made-up example—all examples must be made up—that illustrates the point.

When asked if California could eliminate the growing $26.3 billion deficit in Sacramento, balance the state’s budget, and make state government work again, Governor Arnold Schwarzenegger said “no way, Jose,” referring to his earlier remark that there was “no way in hell” California would be able to balance the budget at this point. He added that “paring deficits in the absence of new revenues will probably wipe out most state jobs & services and our bond rating will become total junk. The last one out the door should turn out the lights.”

You’ll never hear this in the real world, even if it’s mostly true. Governor Schwarzenegger will continue to rally the troops. California will not fold up its tent. The state will do something else instead, like stealing money from—sorry, I meant “borrowing money from”—local municipalities.

Although we humans have been trashing the planet, and continue to trash the planet, Tom Friedman must cling to positive illusions about outcomes. But such unreflective optimism is not supported by reality. Unless a miracle occurs, there is little doubt about the species extinction outcome in the 21st century if we keep doing what we’re doing.

But the power of positive illusions is that “people who remain optimistic in the face of insurmountable odds are healthier and finally more successful than those who have a more realistic attitude.” Thus friedmanism is almost universal among high-functioning, successful human beings. It thus afflicts almost all of our society’s leaders and elites, i.e. those people who are charged with keeping the growth machine running.

Any salesman will attest to the upside of maintaining positive illusions, but there is a downside as well—bankruptcy and destitution.

The antidote to unwarranted optimism—Keanu Reeves takes the Red Pill, not the Blue Pill, in the movie The Matrix—also reflects the cause of The Sixth Extinction. Walt Kelly, the creator of Pogo, tried to put us on the road to sanity on a poster for the first Earth Day in 1970 (Figure 1).

Figure 1 — The road to sanity. It is only when we acknowledge that we—all of us, not just those guys over there—are the problem we’re trying to fix that we can possibly do anything about the problems we create. This is the “consciousness” solution—we need a lot more of it. This is the opposite of friedmanism, in which self-serving cheerleading is a substitute for thought & awareness. More darkly, the dyed-in-the-wool pessimist believes that with Homo sapiens, just as with any other species, what you see is what you get. In other words, Human Nature properly understood forms an insurmountable barrier to making real changes in our collective behavior. Thus over-population or the destruction of other species are non-preventable outcomes of the human condition, even if some people are aware of the need for change. For example, many marine biologists despair about extinctions in the oceans. These biologists are not optimistic, but they carry on, they still fight the good fight. Watch this video of oceanographer Jeremy Jackson talking about how dire the situation in the oceans is.

We humans will have to sleep in the broken bed we have made unless—mirabile dictu—we undertake concerted actions on a global-scale to clean up our act. Genuine progress is possible only if we acknowledge our sins, but doing so conflicts with friedmanism, which offers us reassuring but unjustified positive illusions built upon a naive overconfidence in human capabilities and a nearly total disregard for human failings.

Let’s now turn to the cause and some of the consequences of The Sixth Extinction.

The Holocene Extinction Event

The Holocene Extinction Event is the widespread, ongoing mass extinction of species during the present epoch (10,000 years ago—present). It is called the Sixth Extinction because there have been five other big (not “minor”) mass extinctions in the Phanerozoic Eon which started at the beginning of the Cambrian Period 543 million years ago.

1. The oldest mass extinction occurred at the Ordovician–Silurian boundary (≈439 Mya, [million years ago]). Approximately 25% of the families and nearly 60% of the genera of marine organisms were lost, including deep-shelf benthic faunas (trilobites, graptolites, and conodonts).
2. The next great extinction was in the Late Devonian (≈364 Mya), when 22% of marine families and 57% of marine genera, including nearly all jawless fishes, disappeared. This extinction decimated coral reefs, brachiopods, and calcareous foraminifera.
3. The Permian–Triassic extinction (≈ 251 Mya) was by far the worst of the five mass extinctions; 95% of all species (marine as well as terrestrial) were lost, including 53% of marine families, 84% of marine genera, and 70% of land plants, insects, and vertebrates. This extinction is called “The Great Dying.”
4. The End Triassic extinction (≈199–214 Mya) was associated with the opening of the Atlantic Ocean by sea floor spreading related to massive lava floods that caused significant global warming. Marine organisms were most strongly affected (22% of marine families and 53% of marine genera were lost), but terrestrial organisms also experienced much extinction, including sponges, gastropods, bivalves, cephalopods, brachiopods, insects, and vertebrates
5. The most recent mass extinction was at the Cretaceous–Tertiary boundary (≈65 Mya); 16% of families, 47% of genera of marine organisms, and 18% of vertebrate families were lost. Most notable was the disappearance of nonavian dinosaurs, plus substantial to complete losses among such diverse groups as ammonites, rudists, and certain marine reptiles.

99.9% of all species that lived during the Phanerozoic are now extinct. Species go extinct as a matter of course. What marks a mass extinction is the rate of extinction. When the rate at which species go extinct far exceeds the background, or natural, rate of extinction, you have a mass extinction.

The “fossil” background rate has been estimated at 1 species per year. Another estimate gives 0.5–5 species/year.

Amphibian declines and extinctions are critical concerns of biologists around the world. The estimated current rate of amphibian extinction is known, but how it compares to the background amphibian extinction rate from the fossil record has not been well studied… These calculations suggest that the current extinction rate of amphibians could be 211 times the background amphibian extinction rate. If current estimates of amphibian species in imminent danger of extinction are included in these calculations, then the current amphibian extinction rate may range from 25,039–45,474 times the background extinction rate for amphibians. It is difficult to explain this unprecedented and accelerating rate of extinction as a natural phenomenon.

Living amphibians are not the only taxon (Phylum Chordata, Class Amphibia, Subclass Lissamphibia) affected. Reptiles, birds, fishes and invertebrates, and other classes are also dying out. Extinction rates exceed the fossil record background across the board. This is not a “natural” phenomenon unless you rightly take human actions as part and parcel of Nature, not apart from it. Michael Novacek explains the sole cause of The Sixth Extinction (Figure 2). Figures 3 and 4 show some extinction data.

Figure 2 — Paleontologist Michael Novacek of the American Museum of Natural History explains The Sixth Extinction to an earnest but ultimately uncomprehending Charlie Rose. “Unfortunately when it comes to the sixth extinction, we don’t have any argument about the cause. It’s us. It’s deforestation, destruction of habitats, overhunting, invasive species. These are kind of like the “Four Horseman” of environmental destruction that are contributing to the loss of species today. But what’s important from the perspective of people like myself, who study this long history of organisms, is that this is major, this is a big deal. This is something on the scale of the Cretaceous Extinction, in the ball park. And we’re in the midst of it. What an interesting time we live in, in some perverse way, you might say that we’re witnessing the major events [mass extinctions] in the history of life in our lifetime.” Novacek is the author of Terra: Our 100-Million-Year-Old Ecosystem—And the Threats That Now Put It At Risk.

Figure 3 — Declines since 1970 in marine, freshwater and terrestrial vertebrates. From Global Biodiversity Outlook 2, a publication of the of UNEP’s Convention on Biological Diversity. “Based on published data from around the world, the Living Planet Index aggregates trends of some 3,000 wild populations of species. It shows a consistent decline in average species abundance of about 40% between 1970 and 2000; inland water species declined by 50%, while marine and terrestrial species both declined by around 30%”

Figure 4 — A summary of the IUNC’s Red List of Threatened Species, taken from the blog Dodos Are Gone Forever (see here). Of the species evaluated, 37.8% are threatened with extinction.

In the interest of demolishing friedmanism wherever we find it,  let’s read a now forgotten press release from 1998 describing the results of a poll commissioned by the American Museum of Natural History.

April 20, 1998. The American Museum of Natural History announced today results of a nationwide survey titled Biodiversity in the Next Millennium, developed by the Museum in conjunction with Louis Harris and Associates, Inc. The survey reveals that seven out of ten biologists believe that we are in the midst of a mass extinction of living things, and that this loss of species will pose a major threat to human existence in the next century.

Among the findings revealed by the survey, scientists identified the maintenance of biodiversity – the variety of plant and animal species and their habitats – as critical to human well-being; they rate biodiversity loss as a more serious environmental problem than the depletion of the ozone layer, global warming, or pollution and contamination. The majority (70%) polled think that during the next thirty years as many as one-fifth of all species alive today will become extinct, and one third think that as many as half of all species on the Earth will die out in that time.

[My note: This was 11 years ago. if 20% of all species alive in 1998 were predicted to go extinct in the next 30 years, I would say we’re running right on, if not ahead of, schedule.]

In 1998, most biologists thought biodiversity loss was a more serious environmental problem than global warming. Nobody seems to have asked these underfunded biologists for their opinion since then, or asked them how things are going. No wonder. In 2009, all the politically-correct news focuses on the threats to human welfare posed by anthropogenic climate change. In response, Energy Secretary Steven Chu wants to further screw around with Nature to make 4th generation biofuels so we can all drive to Wal-Mart.

Apparently, biologists don’t study a subject—all life on Earth and all the interdependent ecosystems upon which that life depends—that people deem important. What is the primary driver of The Sixth Extinction? This is taken from Are we in the midst of the sixth mass extinction? A view from the world of amphibians—

Human activities are associated directly or indirectly with nearly every aspect of the current extinction spasm. The sheer magnitude of the human population has profound implications because of the demands placed on the environment. Population growth, which has increased so dramatically since industrialization, is connected to nearly every aspect of the current extinction event.

Climate change merely adds to the extinction problem we’ve already created because we’re not willing to put the brakes on our exponentially increasing population. Dr. Chu wants to create genetically engineered monocultures, a form of geoengineering, to keep growth going. Thus some proposed “solutions” to global warming will just make an already bad situation worse. We have met the enemy, and he is us.

Let’s press on. I briefly discuss some recent developments and findings concerning The Sixth Extinction.

Honeybees and Amphibians

In 2006, honeybees started disappearing. Scientific American tells the story of Don Hackenberg, a beekeeper who moves his hives from place to place to pollinate Florida melons, Pennsylvania apples, and California almonds. Business was brisk, but then an alarming thing happened—

… when [Hackenberg] came back a month later, he was horrified. Many of the
remaining colonies had lost large numbers of workers, and only the young workers and the queen remained and seemed healthy. More than half of [his] 3,000 hives were completely devoid of bees. But no dead bees were in sight. “It was like a ghost town,” Hackenberg said when he called us seeking an explanation for the mysterious disappearance.

Hackenberg was not the only victim.

[A] survey … in the spring of 2007 revealed that a fourth of U.S. beekeepers had suffered similar losses and that more than 30 percent of all colonies had died. The next winter the die-off resumed and expanded, hitting 36 percent of U.S. beekeepers. Reports of large losses also surfaced from Australia, Brazil, Canada, China, Europe and other regions. More recent data are not available yet, but some beekeepers say they have seen their colonies collapse this [last] winter, too. [published in April, 2009].

The bee loss has raised alarms because one third of the world’s agricultural production depends on the European honeybee, Apis mellifera the kind universally adopted by beekeepers in Western countries. Large, monoculture farms require intense pollination activity for short periods of the year, a role that other pollinators such as wild bees and bats cannot fill. Only A. mellifera can deploy armies of pollinators at almost any time of the year, wherever the weather is mild enough and there are flowers to visit.

The die-off of Apis mellifera is now called colony collapse disorder (CCD). Honeybee losses mounted in the 20th century.

Even before colony collapse, honeybees had suffered from a number of ailments that reduced their populations. The number of managed honeybee colonies in 2006 was about 2.4 million, less than half what it was in 1949. But beekeepers could not recall seeing such dramatic winter losses as occurred in 2007 and 2008. Although CCD probably will not cause honeybees to go extinct, it could push many beekeepers out of business.

Probably A. mellifera will not become extinct, at least in the foreseeable future, but that’s actually begging the question, isn’t it? If there were a single, remediable cause of the honeybee die-off, the question of possible extinction would lose much of its force. We need to know why honeybees are dying.

[We] ruled out many potential causes for CCD and found many possible contributing factors. But no single culprit has been identified. Bees suffering from CCD tend to be infested with multiple pathogens, including a newly discovered virus, but these infections seem secondary or opportunistic much the way pneumonia kills a patient with AIDS. The picture now emerging is of a complex condition that can be triggered by different combinations of causes. There may be no easy remedy to CCD. It may require taking better care of the environment and making long-term changes to our beekeeping and agricultural practices.

Honeybees are dying of everything, just like AIDS sufferers with weakened immune systems. This points to environmental stress as the primary cause of the ongoing demise of A. mellifera. If we continue to degrade the environment, the stresses on bees will increase. This will further weaken the bees, which will result in more die-offs, which will increase the probability of extinction over time. Barring extinction, honeybee population declines could easily be severe enough to preclude industrial scale pollination for the various fruits and nuts we eat.

Amphibian declines are a second smoking gun pointing to general environmental degradation as the primary cause of species die-offs. This is described in A view from the world of amphibians—

Paradoxically, although amphibians have proven themselves to be survivors in the past, there are reasons for thinking that they might be vulnerable to current environmental challenges and, hence, serve as multipurpose sentinels of environmental health. The typical life cycle of a frog involves aquatic development of eggs and larvae and terrestrial activity as adults, thus exposing them to a wide range of environments. Frog larvae are typically herbivores, whereas adults are carnivores, thus exposing them to a wide diversity of food, predators, and parasites. Amphibians have moist skin, and cutaneous respiration is more important than respiration by lungs. The moist, well vascularized skin places them in intimate contact with their environment. One might expect them to be vulnerable to changes in water or air quality resulting from diverse pollutants… [etc.]

Chytridiomycosis, a disease of amphibians caused by a newly discovered pathogenic fungus called Batrachochytrium dendrobatidis (Bd), appears to be the proximate cause of many amphibian extinctions. But the root cause is general human degradation of the environment which makes weakened (reduced) populations of frogs (all toads are frogs), salamanders, and caecilians vulnerable to new pathogens.

A new and significant threat to amphibians is a virulent, emerging infectious disease, chytridiomycosis, which appears to be globally distributed, and its effects may be exacerbated by global warming. This disease, which is caused by a fungal pathogen and implicated in serious declines and extinctions of >200 species of amphibians, poses the greatest threat to biodiversity of any known disease… A general message from amphibians is that we may have little time to stave off a potential mass extinction…

Amphibians may be taken as a case study for terrestrial organisms. They have been severely impacted by habitat modification and destruction, which frequently has been accompanied by use of fertilizers and pesticides. In addition, many other pollutants that have negative effects on amphibians are byproducts of human activities. Humans have been direct or indirect agents for the introduction of exotic organisms [introduced predators]. Furthermore, with the expansion of human populations into new habitats, new infectious diseases have emerged that have real or potential consequences, not only for humans, but also for many other taxa, such as the case of Bd and amphibians.

[My note: The origin of Frog Chytrid as an amphibian pathogen and how it has spread around the world is not precisely known, but the leading theories support human meddling.]

Amphibians are victims of The Sixth Extinction and this die-off is a harbinger of more losses to come in other plants and animals.

Peak Fish

A study of fisheries data in 2006 concluded that if the current trend in marine species population declines continues, all such populations will have collapsed by 2048 (Figure 5).

Figure 5 — The graph is based on results reported in Impacts of Biodiversity Loss on Ocean Ecosystem Services by Boris Worm, et. al. (Science, November 3, 2006). “Globally, the rate of fisheries collapses, defined here as catches dropping below 10% of the recorded maximum, has been accelerating over time, with 29% of currently fished species considered collapsed in 2003. This accelerating trend is best described by a power [function], which predicts the percentage of currently collapsed taxa as a function of years elapsed since 1950… The data further revealed that despite large increases in global fishing effort, cumulative yields across all species and large marine ecosystems had declined by 13% (or 10.6 million metric tons) since passing a maximum in 1994.” This last result puts peak fish in 1994.

As I said earlier, people don’t seem overly concerned about plants and animals unless their decline has an immediate negative impact on human welfare. It’s hard to get people worked up about amphibian extinctions in the tropics. (Go here for the full text). That being the case, try this on for size—

Human-dominated marine ecosystems are experiencing accelerating loss of populations and species, with largely unknown consequences. We analyzed local experiments, long-term regional time series, and global fisheries data to test how biodiversity loss affects marine ecosystem services across temporal and spatial scales. Overall, rates of resource collapse increased and recovery potential, stability, and water quality decreased exponentially with declining diversity. Restoration of biodiversity, in contrast, increased productivity fourfold and decreased variability by 21%, on average. We [Worn, et. al.] conclude that marine biodiversity loss is increasingly impairing the ocean’s capacity to provide food, maintain water quality, and recover from perturbations. Yet available data suggest that at this point, these trends are still reversible.

It’s not clear how many species in the oceans will actually go extinct in the 21st century as opposed to becoming very rare. In either case, you can forget all about eating the wild-caught seared sea scallops at The Aquagrill in SoHo, no matter how much money you have. But I don’t want to make light of the fact that vast numbers of people depend on seafood for their survival. Good arguments can be made for giving up seafood altogether if eating it is discretionary. Any fish, crustaceans or mollusks you might eat in 2048 will have to come from aquaculture (Figure 6).

Figure 6 — World fish production and seafood consumption, 1976-2030 from the FAO’s The State of World Fisheries and Aquaculture. “By the year 2030, aquaculture will dominate fish supplies and less than half of the fish consumed is likely to originate in capture fisheries.” You can see peak fish (from capture fisheries) in the data. Of course, aquaculture has its own problems: “Without proper management, aquaculture can put a great deal of strain on the surrounding natural ecosystems. The high densities of organisms, high artificial feed inputs and the subsequent generation of heavy organic loads in the water stream are the primary sources of most of the environmental problems associated with aquaculture.”

The FAO’s projections for wild-caught fish production in 2030 are a tad optimistic in view of the results of Boris Worm and his colleagues (Figure 5). We would reasonably expect all the world’s fisheries to collapse long before the ocean is devoid of healthy fish populations.

Dr. Worm believes the fisheries collapse is still reversible.

According to Mr Worm, [the ocean ecosystems] can [recover]. “The data show us its not too late. We can turn this around.” The answer he says is to create more marine parks. “But less than one percent of the global ocean is effectively protected right now,” Mr Worm said. “We won’t see complete recovery in one year, but in many cases species come back more quickly than people anticipated — in three to five to ten years. And where this has been done we see immediate economic benefits.”

The researchers have concluded that restoring marine biodiversity through an ecosystem based management approach is the only way to reverse the trend. That will require “integrated fisheries management”, pollution control, maintenance of essential habitats and the creation of marine reserves.

They say doing nothing would impose a serious threat to global food security.

Depleted fisheries are another tragedy of the commons. Will a miraculous change in human predation of marine species preserve wildlife in the oceans? I’ll let you be the judge.

Planet of Weeds

If you read only one article or book on The Sixth Extinction, I recommend David Quammen’s Planet Of Weeds (originally published in Harpers, October, 1998). You’ve probably already thought about the obvious question: Will Homo sapiens become a victim of its own misdeeds?

Now we come to the question of human survival, a matter of some interest to many. We come to a certain fretful leap of logic that otherwise thoughtful observers seem willing, even eager to make: that the ultimate consequence will be the extinction of us. By seizing such a huge share of Earth’s landscape, by imposing so wantonly on its providence and presuming so recklessly on its forgivingness, by killing off so many species, they say, we will doom our own species to extinction. This is a commonplace among the environmentally exercised. My quibbles with the idea are that it seems ecologically improbable and too optimistic. But it bears examining, because it’s frequently offered as the ultimate argument against proceeding as we are.

[Paleontologist David] Jablonski also has his doubts. Do you see Homo sapiens as a likely survivor, I ask him or as a casualty? “Oh, we’ve got to be one of the most bomb-proof species on the planet,” he says. “We’re geographically widespread, we have a pretty remarkable reproductive rate, we’re incredibly good at co-opting and monopolizing resources. I think it would take really serious, concerted effort to wipe out the human species.” The point he’s making is one that has probably already dawned on you: Homo sapiens itself is the consummate weed [or weedy species, as Quammen explains in the article.]

I agree with Jablonski. It seems that nothing short of a catastrophic bolide impact, an alien invasion, oceans filled with hydrogen sulfide, or a near-by gamma-ray burst will kill us off, though we can expect human populations to be much reduced in the future. I doubt global warming will do it. And what will happen “after” the extinction?

What will happen after this mass extinction, assuming it proceeds to a worst-case scenario? If we destroy half or two thirds of all living species, how long will it take for evolution to fill the planet back up? “I don’t know the answer to that,” [Jablonski] said. “I’d rather not bottom out and see what happens next.” In the journal paper he had hazarded that, based on fossil evidence in rock laid down atop the K-T event and others, the time required for full recovery might be 5 or 10 million years. From a paleontological perspective, that’s fast. “Biotic recoveries after mass extinctions are geologically rapid but immensely prolonged on human time scales,” he wrote. There was also the proviso, cited from another expert, that recovery might not begin until after the extinction-causing circumstances have disappeared. But in this case, of course, the circumstances won’t likely disappear until we do…

… Even rats and cockroaches are capable — given the requisite conditions; namely, habitat diversity and time — of speciation. And speciation brings new diversity. So we might reasonably imagine an Earth upon which, 10 million years after the extinction (or, alternatively, the drastic transformation) of Homo sapiens, wondrous forests are again filled with wondrous beasts. That’s the good news.

I can’t top David Quammen. As he says, in some millions of years after the current Sixth Extinction, long after we’re gone, the planet will fill up with life again—that’s the good news.

Contact the author at [email protected]