Time to act

I know we really don't need anything else to worry about.  World events have been depressing enough, and here in the United States we've got an election on Tuesday that is making me pop Xanax as if they were Skittles.  But I ran across something in a book I'm reading that was absolutely jaw-dropping, and not in a good way, and I knew I would be seriously remiss in not writing about it here.

I mentioned a few days ago (in a post about some bizarre volcanoes in the East African Rift Zone) that I've been reading Tamsin Mather's wonderful book Adventures in Volcanoland: What Volcanoes Tell Us About the World and Ourselves.  Mather's specialty is monitoring gas production from volcanoes, and using the composition of offgassed material to gather information about magma characteristics and the likelihood of eruptions.  She's traveled all over the world collecting and analyzing samples, comparing hotspot volcanoes (like the ones in Hawaii) to rift volcanoes (like Ol Doinyo Lengai in Tanzania) to trench/subduction volcanoes (like Etna, Vesuvius, Krakatoa, Fujiyama, the Andes, and the North American Cascades).  Her research puts her in position as one of the world's foremost and most knowledgeable experts on volcanic offgassing, and what it means for our understanding of what is going on inside the Earth's mantle.

In her book, she not only references currently-active volcanoes, but prehistoric eruptions -- and one of those she discusses is the astonishingly huge Siberian Traps.  

[Image licensed under the Creative Commons OlgaChuma Ольга Чумаченко, Плато Путорана-3, CC BY-SA 3.0]

This eruption, of a type known as a large igneous province or flood basalt, happened 252 million years ago, at the end of the Permian Period.  Flood basalt eruptions occur when something rifts the crust of the Earth and deep-source, extremely hot basaltic (low silica content) lava flows out.  This lava is incredibly fluid, and fills up valleys like water fills a bowl.  In the case of Siberia, it was a quantity that beggars belief; current estimates stand at around four million cubic kilometers of lava.  The disaster this caused was amplified by the fact that prior to the eruption, the Earth had had a long period of warm, wet climates pretty much worldwide, facilitating the growth of widespread swamps and rainforests.  The age when this occurred is called the Carboniferous Period, so named because all that dead compressed plant matter locked up gigantic quantities of atmospheric carbon, forming enormous seams of coal.

When the Siberian Traps erupted, the lava ripped its way through those massive coal deposits, and the carbon they contained was suddenly returned to the atmosphere as carbon dioxide.  Mather writes:

Estimates of total carbon dioxide emissions over the million-year-scale lifetimes of these basaltic floods are in the region of tens to hundreds of trillion tonnes...  Estimates of varying emission rates over the very long lifetimes of these provinces are harder to make than the totals, but one recent study put the maximum emission rate during the Siberian Traps at around eighteen billion tonnes per year.

The result was widespread disruption of the climate, global marine anoxia, and the largest mass extinction ever -- the Permian-Triassic Extinction, which wiped out on the order of ninety percent of life on Earth.

The kicker comes in the very next paragraph, when Mather tells us that the rate of carbon dioxide production from the most massively devastating volcanic eruption on record, the rock from which covers an area of seven million square kilometers, is half the rate our current fossil fuel use is currently churning out carbon dioxide.

I don't exaggerate when I say I had to read that passage three times before I was convinced I'd understood her correctly.

I've all too frequently heard laypeople give a sneering chuckle at the climatologists, saying stuff like, "What a lot of bullshit.  One volcanic eruption emits more carbon dioxide than all the cars on Earth do."  They rarely cite a source, and when they do it's from something like the fossil-fuel-industry-funded Heartland Institute, but -- because this opinion is a great excuse for continuing to do stuff the same way we always have -- they almost never get challenged on it.

It's astonishing how easy it is to accept a false viewpoint when it gives you a comforting reason not to do anything inconvenient to your lifestyle.

But here's the straight scoop from Tamsin Mather, who (allow me to reiterate) is a volcanologist who specializes in analysis of volcanic offgassing:

Despite the wide error bars in our estimates of the global rate of volcanic carbon degassing, what we can know is that these natural emissions pale into insignificance compared to what humans produce.  In 2019, human fossil-fuel burning released over 35 billion tonnes of carbon dioxide into our atmosphere.  This is seventy times more than even our most generous current estimates of global magmatic carbon degassing.  In 2022, the aviation industry alone emitted 800 million tonnes of carbon dioxide, eclipsing estimates of that from our planet's background tectonism before even considering other sectors of human industry.  We cannot look to Earth's volcanism today to reassure ourselves that our rate of carbon emission might not be too much of a change in terms of our planet's natural cycles.  Powerful as the forces of tectonics that daily drive the slow creep of plate movement and volcanic activity across the globe are, the human race has currently surpassed them in terms of its carbon dioxide flux to the atmosphere.  It is apposite to reflect upon the level of responsibility that should appropriately come with the level of power attained by our species that, by this carbon metric, overwhelms all Earth's volcanoes.

Despite this, we have a candidate for president here in the United States -- I doubt I need to tell you which one -- who has stated he wants to discontinue investment in renewable energy and withdraw from the Paris Accords, and frequently says "Drill baby drill, and frack frack frack!" to cheering crowds.

Anyhow, I'm sorry to post alarming stuff, but perhaps now isn't such a bad time after all.  We have the chance to make a difference not only by our actions and choices, but in the voting booth.  It put me in mind of a conversation that occurs in my novel In the Midst of Lions, which seems a fitting way to end this post:

Mary Hansard's face registered near panic.  "It's not just here.  It’s everything we know.  Soon it’ll all be gone, and if we don’t find a way out, us with it.  We've got to do something, now.”

Soren glanced at Dr. Quaice.  “Okay, this is scaring the shit out of me.”

Mary tightened her grip on Soren’s sleeve.  “Good.  Good.  You should be scared.  Scared people act.” She hitched a sob.  “Complacent people die.”

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Creepy crawlies

Whenever we have a wet summer -- not an uncommon occurrence in our rainy climate -- we have a plague of little pests trying to get into our house.

They're called millipedes, slinky guys maybe a couple of centimeters long, with lots of legs (not a thousand, though).  They're completely harmless; they don't bite like their cousins the centipedes do, and if you poke at them, they coil up into a ball.  So I guess they're really more of a nuisance than an actual problem.  They don't even damage anything, the way mice can.  Mostly what they seem to do is get in through every crack and crevice (there are lots of these in a big old house like ours), look around for a while, then curl up and die.

[Image licensed under the Creative Commons Totodu74, Anadenobolus monilicornis 03, CC BY-SA 3.0]

So I don't like them, and I wish they stayed outside, but in the grand scheme of things they're no big deal.  Imagine, though, if they were bigger.

A lot bigger.

Just last week, paleontologists announced the discovery on a beach in Northumberland, England, of a millipede fossil from the Carboniferous Period.  It's been dated to the middle of the period, about 326 million years ago.  It looks a bit like the millipedes I see trundling across my basement floor in summer.

Only this one was 2.6 meters long (approximately the length of a Mini Cooper), a half a meter across, and weighed something on the order of fifty kilograms.

It's been named Arthropleura, and holds the record as the largest-known arthropod in Earth's history.  Nothing is known for sure about its behavior; if it's like the rest of millipedes, it was a scavenger on leaf detritus, but there's no way to know for certain.  Given its size, it could well have been a lot more dangerous than the ones we have around now.  To paraphrase the old joke about five-hundred-pound gorillas:

Q:  What does a fifty-kilogram millipede eat?

A:  Anything it wants.

Those of you who are (like me) biology nerds may be frowning in puzzlement at this point.  How on earth could an arthropod get so big?  Their size is limited by the inefficiency of their respiratory system (not to mention the weight of their exoskeletons).  Most arthropods (millipedes included) breathe through pairs of holes called spiracles along the sides of the body.  These holes open into a network of channels called tracheae, which bring oxygen directly to the tissues.  Contrast that with our system; we have a central oxygen-collecting device (lungs), and the hemoglobin in our blood acts as a carrier to bring that oxygen to the tissues.  It's a lot more efficient, which is why the largest mammals are a great deal bigger than the largest arthropods.  (So, no worries that the bad sci-fi movies from the 50s and 60s, with giant cockroaches attacking Detroit, could actually happen.  A ten-meter-long cockroach not only wouldn't be able to oxygenate its own tissues fast enough to survive, it couldn't support its own weight.  It wouldn't eat Detroit, it would just lie there and quietly suffocate.)

So how could there be such ridiculously enormous millipedes?

The answer is as fascinating as the beast itself is.  As the temperature warmed and rainfall increased after the previous period (the Devonian), it facilitated the growth of huge swaths of rain forest across the globe.  In fact, it's the plant material from these rain forests that produced the coal seams that give the Carboniferous its name.  But the photosynthesis of all these plants drove the oxygen levels up -- by some estimates, to around 35% (contrast that to the atmosphere's current 21% oxygen).  This higher oxygen level facilitated the growth of animals who are limited by their ability to uptake it -- i.e., arthropods.  (At the same time, there was a dragonfly species called Meganeura with a seventy-centimeter wingspan.  And unlike millipedes, these things were carnivores, just as modern dragonflies are.)

Eventually, though, the system was unsustainable, and a lot of the rain forests began to die off in the Late Carboniferous, leading to a drier, cooler climate.  However, remember the coal seams -- by that time a huge percentage of the carbon dioxide that had fed the photosynthesis of those rain forests was now locked underground.  The fuse was lit for a catastrophe.

Fast forward to the end of the next period, the Permian, 255 million years ago.  What seems to have happened is a series of colossal volcanic eruptions that created the Siberian Traps, a basalt deposit covering most of what is now Siberia.  The lava ripped through the coal seams, blasting all that stored carbon into the atmosphere as carbon dioxide.  The temperature in the late Permian had been cool and dry, and the spike of carbon dioxide created a commensurate spike in the temperature -- as well as a huge drop in oxygen, used up by the burning coal.  The oxygen concentration seems to have bottomed out at around twelve percent, just over half of what it is now.  The extra carbon dioxide dissolved into ocean water, dropping the pH, and the increasing acidity dissolved away the shells of animals who build them out of calcium carbonate -- e.g. corals and mollusks.

Wide swaths of ocean became anoxic, acidic dead zones.  The anaerobic organisms began to eat through all the dead organic matter, churning out more carbon dioxide and another nasty waste product, sulfur dioxide (which gives the horrible smell to rotten eggs, and is also an acidifier).  The result: an extinction that wiped out an estimated ninety percent of life on Earth.  In short order, a thriving planet had been turned into a hot, dead, foul-smelling wasteland, and it would take millions of years to recover even a fraction of the previous biodiversity.

Of course, at highest risk would be the big guys like our friends Arthropleura and Meganeura, and the Earth hasn't seen giant arthropods like this since then.  Today, the largest arthropod known is the Japanese spider crab (Macrocheira), topping out at around twenty kilograms -- but crabs and other crustaceans have gills and an oxygen carrier called hemocyanin, so they can boost the efficiency of their respiratory system somewhat over their terrestrial cousins.  The largest insect today is the African Goliath beetle (Goliathus), at about a tenth of a kilogram.  And in today's atmosphere, it's at a pretty significant disadvantage.  They may look big and scary, but in reality, they're slow-moving, harmless creatures.  Kind of a beer can with six legs, is how I think of them.

So that's today's look at creepy-crawlies of the past.  In my opinion it's just as well the big ones became extinct.  The last thing I need is having to shoo a fifty-kilogram millipede out of my basement.

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Neil deGrasse Tyson has become deservedly famous for his efforts to bring the latest findings of astronomers and astrophysicists to laypeople.  Not only has he given hundreds of public talks on everything from the Big Bang to UFOs, a couple of years ago he launched (and hosted) an updated reboot of Carl Sagan's wildly successful 1980 series Cosmos.

He has also communicated his vision through his writing, and this week's Skeptophilia book-of-the-week is his 2019 Letters From an Astrophysicist.  A public figure like Tyson gets inundated with correspondence, and Tyson's drive to teach and inspire has impelled him to answer many of them personally (however arduous it may seem to those of us who struggle to keep up with a dozen emails!).  In Letters, he has selected 101 of his most intriguing pieces of correspondence, along with his answers to each -- in the process creating a book that is a testimony to his intelligence, his sense of humor, his passion as a scientist, and his commitment to inquiry.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

A bolt from the blue

Two weeks ago, I wrote about a surprising fossil find in China showing that insects had rebounded after the horrific Permian-Triassic Extinction, 252 million years ago, with amazing speed considering the scale of the extinction and how slowly evolution generally goes.  An extinction opens up hundreds or thousands of ecological niches, which increases the selective pressure on the survivors to occupy them and avoid competition with the others -- which insects did, par excellence, and have been doing ever since.

The cause of the "Great Dying" has been a subject of conjecture for as long as we've known about it.  Candidates include:

• The formation of the Siberian Traps, an unimaginably huge lava flow covering most of eastern Siberia.  (Its volume is estimated at four hundred million cubic kilometers.)  The eruption would have burned everything in its wake, pumping tons of carbon dioxide into the atmosphere, and it would have released huge amounts of sulfur dioxide -- not only a poison, but one of the most powerful greenhouse gases.  The result; massive global warming and a catastrophic change in ecosystems worldwide.
• The lockup of Pangaea.  The collision of smaller continents to form a supercontinent has a number of effects -- the eradication of coastline along the colliding margin, ecological changes from shifting ocean currents, and collapse of mid-ocean ridges (resulting in a huge drop in sea level) among them.
• A "methane burp."  This sounds innocuous, but really, really isn't.  There's a tremendous amount of methane locked up in the form of clathrates -- a network of water ice with methane trapped inside.  These "frozen methane hydrates" coat the entire deep ocean floor.  The stuff is stable under cold temperatures and high pressures, but if something disturbs them, they begin to come apart, releasing bubbles of methane gas.  The bubbles expand as they rise, displacing more and more water, and when they hit the surface it causes a tsunami, not to mention releasing tons of methane into the atmosphere, which is not only toxic, it's also a greenhouse gas.
• Bombardment by swarms of comets and/or meteorites.  The problem with confirming this hypothesis is that any geological evidence of meteorite collisions would be long since eroded away.  If the object(s) that impacted the Earth were metallic meteorites, it's possible that you could use the same technique Luis Alvarez pioneered to explain the Cretaceous Extinction, which wiped out most of the dinosaurs -- enrichment of a layer of sediment by dust that's high in metallic elements not found in large quantities elsewhere.  But if it was a comet (mostly ice) or a rocky meteorite, we might not see much in the way of evidence of the event.

We just got a new piece of the puzzle last week, from research that also took place in China at a rock outcropping called the Penglaitan Section.  This formation dates from just before and just after the Permian-Triassic Extinction, and has the advantage of being 27 meters thick -- the sediment was being deposited rapidly when it formed, which means that you can see fine gradations in composition and narrow down the time range for when things happened.  (By comparison, the previous formation used is only 30 centimeters thick.)

Part of the Penglaitan Section [Image by Shuzhong Shen]

And what Penglaitan tells us is rather alarming.  The Permian-Triassic Extinction, which wiped out 95% of life on Earth and dwarfed the more familiar Cretaceous Extinction, happened in a relative flash.  And it wasn't (or wasn't solely) caused by temperature rise; the main pulse of extinctions happened suddenly, without any warning, and occurred when the temperature had only started its upward trajectory.  There was a five-degree temperature increase that occurred at the same time as the extinctions, but a much larger increase followed that, after the vast majority of the extinctions had already taken place.

Right now, the leading hypothesis is that the eruption of the Siberian Traps is the most likely cause.  But that in itself is horrific; it means that this colossal outpouring of lava not only happened suddenly, it happened with no warning.  Immediately prior to the extinction event, life was doing just fine -- the biodiversity was high, and there were no minor die-offs to presage the big one that was coming.

"We thought we would see a gradual decline in the diversity of life forms or, for example, certain species that are known to be less resilient than others, we would expect them to die out early on, but we don’t see that, said Jahandar Ramezani, of MIT's Department of Earth, Atmospheric, and Planetary Sciences.  "We can say there was extensive volcanic activity before and after the extinction, which could have caused some environmental stress and ecologic instability.  But the global ecologic collapse came with a sudden blow, and we cannot see its smoking gun in the sediments that record extinction...  The key in this paper is the abruptness of the extinction.  Any hypothesis that says the extinction was caused by gradual environmental change during the late Permian — all those slow processes, we can rule out.  It looks like a sudden punch comes in, and we’re still trying to figure out what it meant and what exactly caused it."

So that's pretty scary.  The idea that something on this scale could strike with essentially no warning whatsoever makes me realize how precarious life is, and how easily the interconnections between ecosystems that keep everything going could be disrupted -- not to mention the scale of the destruction if that happens.

Anyone out there still wondering why I'm so alarmed at the rate at which we're pouring fossil-fuel-derived carbon dioxide into the atmosphere?

Anyhow, that's our cheery message for today.  Monkey around with the ecosystem, and you could kill 95% of life on Earth.  I mean, I don't think it's likely to happen day after tomorrow, or anything, but the fragility of it all should give you pause.

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This week's Skeptophilia book recommendation is a fun one.  If you've never read anything by Mary Roach, you don't know what you're missing.  She investigates various human phenomena -- eating, space travel, sex, death, and war being a few of the ones she's tackled -- and writes about them with an analytical lens and a fantastically light sense of humor.  This week, my recommendation is Spook, in which she looks at the idea of an afterlife, trying to find out if there's anything to it from a scientific perspective.  It's an engaging, and at times laugh-out-loud funny, read.

[If you purchase the book from Amazon using the image/link below, part of the proceeds goes to supporting Skeptophilia!]

Relics of a lost age

If I can be allowed to geek out a little, today's post is about two new discoveries in the field of paleontology.

The mid-Permian period was (1) a challenging time to live, when the climate was rapidly warming and drying, and (2) at 270 million years before the present, was a really long time ago.  Not only was the climate getting dicey, the world was heading for catastrophe -- the lockup of the supercontinent Pangaea, as all the world's land masses fused into one and the rest of the Earth was covered by a giant ocean, is thought to have been the kickoff to the largest wipeout the Earth has ever seen -- the Permian-Triassic extinction.  Not only did the formation of the supercontinent (and superocean) 252 million years ago drastically change the climate, the event coincided with the formation of the Siberian Traps, when four million cubic kilometers of basaltic lava flowed out over what is now eastern Russia.  The resulting massive burning of organic matter spiked the carbon dioxide content of the atmosphere, simultaneously causing the oxygen content to crash and triggering a warm-up that resulted in average ocean surface temperatures of 40 C (104 F).

The result: 95% of the species on Earth became extinct.

Of course, one of the lineages that made it through the bottleneck was our own ancestors.  Back in the mid-Permian -- pre-mass-extinction -- there was a group of protomammals called Gorgonopsians, which included some seriously scary carnivores (one, Inostrancevia, had a 45-centimeter-long skull and saber teeth -- preceding the more famous "saber-toothed tiger" Smilodon by a good 260 million years).

Permian protomammal fossils are quite rare, however.  So it's pretty awesome that paleontologist Christian Kammerer, paleontology curator of the North Carolina Museum of Natural Sciences, discovered fossils of not one, but two new species of mid-Permian protomammals in a small museum in Russia.

Called Gorynychus matsyutinae and Nochnitsa geminidens, the two were drastically different in size.  Gorynychus was probably one of the apex predators of its time, with a 25-centimeter-long skull and big, nasty, pointy teeth.  Nochnitsa, also a predator, was weasel-sized.  The genera were both named after beasts from Russian mythology -- the three-headed dragon Zmey Gorynych and the malevolent, vampiric night spirit Nochnitsa.

Artist's reconstruction of Gorynychus and Nochnitsa [by Matt Celeskey @clepsydrops, from the press release from the North Carolina Museum of Natural Sciences; used with permission]

These lineages both made it through the bottleneck, but not unscathed.  Their descendants, eighteen or so million years later, underwent some rapid evolution during the Permian-Triassic extinction, especially with respect to size.  "In the age before the dinosaurs, when protomammals were the dominant life on land, you had two different groups that switch off on which is the top predator," Kammerer said.  "You have wolf- to lion-sized saber tooth animals wiped out by a mass extinction, and [the Nochnitsa-like animals] take over.  But [Gorynychus-like animals] aren’t wiped out altogether in this extinction, and they take over and become a small insect eating predator, not large carnivores anymore."

Kammerer and his co-author (and co-discoverer of the fossils), Vladimir Matsyutin of the Vyatka Paleontological Museum of Kirov, Russia, were excited not only about having found fossils of two hitherto-unknown species, but about the potential for other discoveries tucked away in museums.  "I would guarantee you there are thousands of undescribed species in museum collections,” Kammerer said.  "Most new species are found in museum collections for the sole reason that there are literally millions of species on Earth today and many more in the fossil record.  When you’re going out and collecting specimens, you won’t know those things.  The people in the museum knew they were protomammals but they didn’t know they were new species."

So that's today's cool science story, about some of our (very) distant relatives.  I've always been fascinated with the early mammals -- for some reason, much more than the charismatic megafauna that were just getting their start at the same time (the dinosaurs, of course).  And the fact that these critters were out doing their thing as the Earth was heading toward the largest catastrophic extinction ever just adds a nice little frisson to the discovery.  You kind of want to warn them about what's coming, you know?

Oh, well, probably wouldn't have helped.  It's not like you can hide from four million cubic kilometers of lava.

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This week's recommended read is Wait, What? And Life's Other Essential Questions by James E. Ryan.  Ryan frames the whole of critical thinking in a fascinating way.  He says we can avoid most of the pitfalls in logic by asking five questions: "What?"  "I wonder..." "Couldn't we at least...?" "How can I help?" and "What truly matters?"  Along the way, he considers examples from history, politics, and science, and encourages you to think about the deep issues -- and not to take anything for granted.