Assessing a collapse

One of the coolest things about science is the cross-fertilization that happens between disciplines.

I'm always impressed when I see examples of this, and my reaction is usually, "How did you even think of doing that?"  It is, at its core, a highly creative process.  The best science involves looking at a problem from a different angle, drawing in data or methods from other disciplines, and putting the whole thing together in such a way that the answer is clear.  (Or at least, a piece of it is clearer than it was before.)  As Hungarian biochemist Albert von Szent-Györgyi put it, "Discovery consists of seeing what everyone has seen, and thinking what no one has thought."

The creative aspect of science struck me while I was reading an article yesterday in Ars Technica about a some new research into a historical puzzle: the sudden collapse of the Shang Dynasty in China, about three thousand years ago.  The Shang were in power for nearly six centuries -- a pretty long time for a single dynastic regime -- and had made some significant accomplishments, the most notable of which were the first recorded writing system for Chinese, and amazing advances in pottery making and bronze casting.  Then -- over a very short period, perhaps only a few years -- Shang rule imploded.  A rival group called the Zhou took advantage of the chaos to defeat the Shang in a bloody battle, then scattered the remaining Shang supporters throughout the land to assure they'd never be able to rise again.

Now, researchers at Nanjing University, led by meteorologist Ke Ding, have drawn on a variety of disparate fields -- meteorology, climatology, geology, archaeology, paleontology, and analysis of extant historical records -- to try to create a complete picture of the causes behind the Shang Dynasty's sudden demise.

Their conclusion: the collapse of the Shang was the consequence of a long line of dominoes that started with a series of prolonged and powerful El Niño events, thousands of kilometers away.

Paleontologists analyzing fossil remains in strata off the coast of Peru dating to around 1000 B.C.E. note a shift from cold-water species to those that favor warmer water.  The fact that there wasn't an oscillation back and forth, but a replacement by warm-water species that lasted perhaps a century, suggests that rather than the usual pendulum swing of El Niño/La Niña conditions -- the former causing a warmup of the surface waters off the west coast of South America, the latter a corresponding cooldown -- in the years before the Shang collapse, the climate seems to have switched over to a semi-permanent El Niño.  What would be the outcome of such a shift in the ENSO (El Niño Southern Oscillation)?  This is where the meteorologists and climatologists took over; they estimated the degree of warmup, and let their computer models predict what effects that would have.

One thing that popped out of the models was a drastic increase in the strength of Pacific typhoons, and a significant change in their paths.  The warmup shifted wind patterns, tracking large storms away from Australia (thus the droughts and wildfires in Australia and Indonesia that usually accompany El Niño years), and northward into China.  Typhoons, though, usually fizzle once they cross over from ocean to land; and the capital of the late Shang Dynasty was Zhaoge, in Henan Province, far away from the coast.  So how would typhoons have affected an inland city so drastically?

But the models showed that the altered wind direction didn't just shove storms toward China, it also fed warm, moist air inland -- atmospheric rivers.  These air currents flow until they meet a mountain range, and the humid air masses experience adiabatic cooling as they rise in elevation, causing them to dump their moisture as rain or snow on the windward sides of mountains.

In other words, the rain shadow effect.  The outcome; suddenly northern and central China were way wetter than they had been.

Now, enter the archaeologists.  One of the most common items in Shang-age archaeological sites are oracle bones -- usually the scapulae of ox, horses, or deer that are thrown into a fire, and the resulting cracks and scorch marks read by a shaman.  But fortunately for us, the shamans -- recall the Shang's development of the first Chinese writing system -- also recorded on the oracle bones what questions had been asked, and what the shaman's assessment of the results had been (i.e., the answer to the question).

And in the last fifty years of the Shang Dynasty, just about all of the oracle bones have to do with the weather.  A lot of them basically ask, "When the hell is it going to stop raining?"

A Shang Dynasty oracle bone [Image licensed under the Creative Commons Orakelknochen, CC BY-SA 3.0]

At the same time as this, the archaeologists also note the abandonment of village sites near riverbanks, an increase in burial of sites under riverine sediments, and the relocation of towns onto higher ground.

What Ke Ding and his colleagues concluded is that the Shang were weakened by years of floods, probably accompanied by poor harvests and resulting famine.  This set the stage for the Zhou rebellion, and the destruction of a dynasty that had ruled China for six centuries.

Now, here's the kicker.  The researchers caution that we're seeing a similar pattern today -- anthropogenic global warming is increasing oceanic surface temperatures, and the Pacific Ocean is seeing extended and more powerful El Niño events.  As Mark Twain observed, "History doesn't repeat, but it often rhymes."

Oh, except that noted climate scientist Donald Trump has evaluated the available data, and decided that global warming is a hoax, and the climatologists are big fat poopyheads.  So there's that.

Anyhow, it's a fascinating and elegant piece of research, and shows how creative the scientific enterprise can be.  Collaboration is the heart of discovery, and here we have an entire team of experts from disparate fields pitching in together to solve a historical puzzle.  One that, despite Trump's pronouncements, we had damn well better pay attention to today.

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The shifting sands

In H. P. Lovecraft's wildly creepy story "The Shadow Out of Time," we meet a superintelligent alien race called the Yith who have a unique way of gathering information.

The Yith, who lived in what is now Australia's Great Sandy Desert some 250 million years ago, are capable of temporarily switching personalities with other intelligent beings throughout the cosmos and from any time period.  While the consciousness of the kidnapped individual is residing in its temporary Yith body, it enjoys the freedom to learn anything it wants from the extensive library of information the Yith have gleaned -- as long as the individual is willing to contribute his/her own knowledge to the library.  The main character, early twentieth century professor Nathaniel Peaslee, is switched, and while he is living with the Yith he meets a number of luminaries whose personalities have also been swiped, including:

• Titus Sempronius Blaesus: a Roman official from 80 B.C.E.
• Bartolomeo Corsi: a twelfth-century Florentine monk
• Crom-Ya: a Cimmerian chief who lived circa 15,000 B.C.E.
• Khephnes: a Fourteenth Dynasty (circa 1700 B.C.E.) Egyptian pharaoh
• Nevil Kingston-Brown: an Australian physicist who would die in 2518 C.E.
• Pierre-Louis Montagny: an elderly Frenchman from the time of Louis XIII (early seventeenth century)
• Nug-Soth: a magician from a race of conquerors in16,000 C.E,
• S'gg'ha: a member of the star-headed "Great Race" of Antarctica, from a hundred million years ago
• Theodotides: a Greco-Bactrian official of 200 B.C.E.
• James Woodville: a Suffolk gentleman from the mid-seventeenth century
• Yiang-Li: a philosopher from the empire of Tsan-Chan, circa 5000 C.E.

Compared to most of the gory dismemberments other Lovecraftians entities were fond of, the Yith are remarkably genteel in their approach.  Of course, it's not without its downside for the kidnapped individual; not only do they lose control over their own bodies for a period up to a couple of years, they experience serious disorientation (bordering on insanity in some cases) upon their return to their own bodies.

Nevertheless, it's a fantastic concept for a story, and I remember when I first read it (at about age sixteen) how taken I was with the idea of being able to meet and talk with individuals from both past and future, not to mention other species. But what struck me most viscerally when I read it was when Peaslee, in the Yith's body, describes what he sees surrounding the library.

It's a tropical rain forest.  What now is a barren desert, with barely a scrap of vegetation, was a lush jungle:

The skies were almost always moist and cloudy, and sometimes I would witness tremendous rains.  Once in a while, though, there would be glimpses of the Sun -- which looked abnormally large -- and the Moon, whose markings held a touch of difference from the normal that I could never fathom.  When -- very rarely -- the night sky was clear to any extent, I beheld constellations which were nearly beyond recognition.  Known outlines were sometimes approximated, but seldom duplicated; and from the position of the few groups I could recognize, I felt I must be in the Earth's southern hemisphere, near the Tropic of Capricorn.

The far horizon was always steamy and indistinct, but I could see that great jungles of unknown tree ferns, Calamites, Lepidodendron, and Sigillaria lay outside the city, their fantastic fronds waving mockingly in the shifting vapors...  I saw constructions of black or iridescent stone in glades and clearings where perpetual twilight reigned, and traversed long causeways over swamps so dark I could tell but little of their towering, moist vegetation.

[Image licensed under the Creative Commons Carl Malamud, Cretaceous Diorama 2, CC BY 2.0]

I think it's the first time I'd really gotten hit square between the eyes with how different the Earth is now than it had been, and that those changes haven't halted. In the time of Lovecraft's Yith, 250 million years ago, where I am now (upstate New York) was underneath a shallow saltwater ocean.  Only a hundred thousand years ago, where my house stands was covered with a thick layer of ice, near the southern terminus of the enormous Laurentide Ice Sheet.  (In fact, the long, narrow lakes that give the Finger Lakes Region its name were carved out by that very glacier.)

I was immediately reminded of that moment of realization when I read a paper in Nature called "Temperate Rainforests Near the South Pole During Peak Cretaceous Warmth," by a huge team led by Johann Klages of the Alfred-Wegener-Institut Helmholtz-Zentrum für Polar und Meeresforschung, of Bremerhaven, Germany.  Klages's team made a spectacular find that demonstrates that a hundred million years ago, Antarctica wasn't the windswept polar desert it currently is, but something more like Lovecraft's vision of the site of the prehistoric library of Yith.  The authors write:

The mid-Cretaceous period was one of the warmest intervals of the past 140 million years, driven by atmospheric carbon dioxide levels of around 1,000 parts per million by volume.  In the near absence of proximal geological records from south of the Antarctic Circle, it is disputed whether polar ice could exist under such environmental conditions.  Here we use a sedimentary sequence recovered from the West Antarctic shelf—the southernmost Cretaceous record reported so far—and show that a temperate lowland rainforest environment existed at a palaeolatitude of about 82° S during the Turonian–Santonian age (92 to 83 million years ago).  This record contains an intact 3-metre-long network of in situ fossil roots embedded in a mudstone matrix containing diverse pollen and spores.  A climate model simulation shows that the reconstructed temperate climate at this high latitude requires a combination of both atmospheric carbon dioxide concentrations of 1,120–1,680 parts per million by volume and a vegetated land surface without major Antarctic glaciation, highlighting the important cooling effect exerted by ice albedo under high levels of atmospheric carbon dioxide.

It's a stunning discovery from a number of perspectives.  First, just the wonderment of realizing that the climate could change so drastically.  Note that this wasn't, or at least wasn't entirely, because of tectonic movement; the site of the find was still only eight degrees shy of the South Pole even back then.  Despite that, the warmth supported a tremendous assemblage of life, including hypsilophodontid dinosaurs, labyrinthodontid amphibians, and a diverse flora including conifers, cycads, and ferns.  (And given that at this point Antarctica and Australia were still connected, Lovecraft's vision of the home of the Yith was remarkably accurate.)

So, if it wasn't latitude that caused the warm climate, what was it?  The other thing that jumps out at me is the high carbon dioxide content of the atmosphere back then -- 1,000 parts per million.  Our current levels are 410 parts per million, and going up a steady 2.5 ppm per year.  I know I've rung the changes on this topic often enough, but I'll say again -- this is not a natural warm-up, like the Earth experienced during the mid-Cretaceous.  This is due to our out-of-control fossil fuel use, returning to the atmosphere carbon dioxide that has been locked up underground for hundreds of millions of years.  When the tipping point will occur, when we can no longer stop the warm up from continuing, is still a matter of debate.  Some scientists think we may already have passed it, that a catastrophic increase in temperature is inevitable, leading to a complete melting of the polar ice caps and a consequent rise in sea level of ten meters or more.

What no informed and responsible person doubts any more is that the warm-up is happening, and that we are the cause.  People who are still "global warming doubters" (I'm not going to dignify them by calling them skeptics; a skeptic respects facts and evidence) are either woefully uninformed or else in the pockets of the fossil fuel interests.

I don't mean to end on a depressing note.  The Klages et al. paper is wonderful, and gives us a vision of an Earth that was a very different place than the one we now inhabit, and highlights that what we have now is different yet from what the Earth will look like a hundred million years in the future.  It brings home the evocative lines from Alfred, Lord Tennyson's wonderful poem "In Memoriam:"

There rolls the deep where grew the tree.
O Earth, what changes hast thou seen?
There where the long road roars hath been
The stillness of the central sea.
The hills are shadows, and they flow
From form to form, and nothing stands;
They melt like mist, the solid lands,
Like clouds, they shape themselves and go.

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Pressing reset

Although you don't tend to hear much about it, the Ordovician Period was a very peculiar time in Earth's history.

From beginning (485 million years ago) to the end (444 million years ago) it experienced two of the biggest global climatic swings the Earth has ever seen.  In the early Ordovician the climate was a sauna -- an intense greenhouse effect caused the highest temperatures the Paleozoic Era would see, and glacial ice all but vanished.  Life was abundant in the shallow seas.  One of the dominant groups were the conodonts:

[Image licensed under the Creative Commons Prehistorica, Panderodus unicostatus, CC BY-SA 4.0]

Those of you who know your fish might guess that conodonts like Panderodus were related to modern lampreys, and you're right.  But it took a really long time to figure that out.  Their soft bodies didn't fossilize well, so about all that we had were the cone-shaped teeth that gave them their name.  In fact, those teeth are the most common fossils in Ordovician sedimentary rocks, so we knew whatever grew them must have been abundant -- but it took a while to determine what kind of animal they came from.

So things were warm, humid, with tropical conditions virtually pole to pole.  Then... something happened.  We're still not entirely sure what.  Part of it was undoubtedly simple plate tectonics; the supercontinent of Gondwana was gradually moving toward the South Pole.  There's some evidence of a large meteorite strike, or possibly more than one.  But whatever the cause, by the end of the Ordovician, glaciers covered much of what is now Africa and South America, resulting in a drastic drop in sea level and a massive extinction that wiped out an estimated sixty percent of life on Earth.  

At this point, life was confined to the oceans. The first terrestrial plants and fungi wouldn't evolve until something like twenty million years after the beginning of the next period, the Silurian, and land animals only followed after that.  As the Ordovician progressed, and more and more ocean water became locked up in the form of glacial ice, much of what had been shallow, temperate seas dried up to form cold, barren deserts.  And that was all there was on land -- thousands of square kilometers of rock, sand, and ice, without a single living thing larger than bacteria to be found anywhere.

Then, the climate reversed again.  The seas flooded back in, and the warmer, sulfur-rich, oxygen-poor water upwelling from the bottom knocked out about twenty percent of the cold-adapted survivors.  By the time the period ended, the Earth had a seriously impoverished biosphere, with something like fifteen percent of the original biota making it through the double-whammy.

But what survived this pair of climate swings was to shape Earth's biological history forever.  Because it included primitive vertebrates with paired jaws -- the gnathostomes -- which became the ancestors of 99% of modern vertebrate animals, including ourselves.

The reason this comes up is some new research out of the Okinawa Institute of Science and Technology that analyzed thousands of fossils from species that made it through the Late Ordovician bottleneck -- and an equal number of those that didn't.  And they found two interesting patterns.  First, the survivors were mostly species that found their way into refugia -- small, isolated pockets of ecosystems with (slightly) more hospitable conditions that allowed them to squeak their way through the worst times.  Second, each of the major extinction pulses was followed by dramatic diversification, as the surviving populations expanded into niches vacated by the ones that weren't so fortunate.

"We pulled together two hundred years of late Ordovician and early Silurian paleontological research," said study lead author Wahei Hagiwara.  "By reconstructing the ecosystems within these refugia, we were able to measure changes in genus-level diversity over time.  Our analysis revealed a steady but striking rise in jawed vertebrate diversity following the extinction.  And the trend is clear -- the mass extinction pulses led directly to increased speciation after several millions of years."

As Ian Malcolm so accurately put it, "Life, uh, finds a way."

A couple of other things strike me about this research, though.

The first is how contingent our existence here is.  Evolutionary biologist Stephen Jay Gould wrote a provocative piece about "replaying the tape of life," coming to the conclusion if you were to start over from the beginning, so much of the path of evolution has rested on chance occurrences that the chances of it turning out exactly the same way is nearly zero.  In a situation like the Late Ordovician Mass Extinction, which assortment of species made it into the few hospitable refugia must have had as much to do with luck as with being well-adapted; had a different set of populations survived, life today almost certainly would look very different.

The second is the fact that both of the Ordovician climate swings were far slower than what we're currently doing to the environment.  Like, hundreds of times slower.  The second one, in fact -- the warm-up and subsequent melting of polar ice -- was almost certainly a very gradual rebound toward the greenhouse conditions that were to pertain by the mid-Silurian.  We're talking about something on the order of ten million years to go from cool to warm.

What we're doing now has taken only a couple of hundred.

What happened in the Late Ordovician should be a wake-up call for us.  Yet somehow, we arrogant humans think we're immune to the effects of our out-of-control fossil fuel burning.  We have a striking fossil record documenting the terrible effects of rapid climate change in prehistory; at the moment, mostly what we seem to be doing is saying, "Yeah, but it won't happen to us, 'cuz we're special."

So that's our cautionary tale for today.  The climate change deniers are fond of saying, "Earth's climate has changed many times before now," and almost never add, "... and when it did, enormous numbers of species went extinct."  And the difference, too, is that the natural fluctuations (such as those caused by plate movement, asteroid strikes, and changes in insolation) aren't something we could control even if we wanted to, but what we're doing now is entirely voluntary.

And until the people in charge realize that addressing climate change is in all of our best interest, I'm afraid our path forward is not likely to change.

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Best laid plans

Let me start out by saying that what you're about to read is in no way meant to be critical of scientists in general, nor the entire scientific endeavor.

What I want to emphasize right from the beginning, though, is that however supportive I am of science, it is inherently incomplete.  We fill in pieces, and move toward a more thorough understanding of the universe -- it's undeniable that we know more now than we did five hundred, or a hundred, or even fifty years ago -- but there are still edges of our knowledge, and entire realms that are only partly understood.  Nearly all scientists are themselves aware of this, and consider the "perimeter of our ignorance" (to use Neil deGrasse Tyson's pithy term) not to be a problem, but an impetus to further inquiry.

That said, the familiar student's complaint of "why do we have to learn this stuff when it could all be disproven tomorrow?" is nothing more than an excuse for laziness; at this point, the overturning of entire disciplines in the fashion that Copernicus, Kepler, and Newton did for physics and astronomy, Mendel (and many others) did for genetics, and Darwin did for evolutionary biology, is vastly unlikely.  About the only area of science that still has enough odd and contradictory data (with dozens of competing models vying for acceptance) to qualify as a candidate for a major overhaul is astrophysics, with its dark energy and dark matter and cosmic inflation and cosmological constants, none of which have come together into a coherent whole.  (Yet.)

But.  It bears keeping in mind that the systems scientists study are complex, and the models they use to make predictions are often based on qualifications, assumptions, and idealizations.  That doesn't mean they're worthless or unrealistic; just that they need to be used with caution.

This is why I was horror-struck by the recent suggestion of using stratospheric aerosol injection to combat anthropogenic climate change.

Because apparently the obvious solution -- investing in conversion to renewable energy sources, and phasing out fossil fuels -- is a pill too bitter to swallow for our political leaders, people are casting about for other ways to combat the warm-up while continuing to burn our way through the Earth's sequestered carbon.  And one of the ideas was to copy what volcanic eruptions do, and blow huge clouds of fine particulates into the upper atmosphere, which would block sunlight and cool the Earth's surface.

There's no doubt that the idea has some factual basis.  You probably know that the 1815 eruption of Mount Tambora, in Indonesia, generated so much ejecta that the following year was called "the Year Without a Summer," and temperatures dropped enough that crops failed across the globe (and here in my home of upstate New York they had snow falling in July).

The problem, though, is that climate is a complex, multi-variable system, which is why meteorologists still have difficulty making long-range forecasts.  They're vastly better than they used to be; the deadliest natural disaster in the history of the United States, the 1900 Galveston hurricane, struck with almost no warning, leaving tens of thousands of people without enough time to get to high ground.  But even considering how much the science has improved, using something like stratospheric aerosol injection to cool the globe is basically a climatological game of Jenga.

[Image licensed under the Creative Commons Guma89, Jenga distorted, CC BY-SA 3.0]

Fortunately, the scientists themselves are sounding the alarm.  A study just released from Columbia University has shown in no uncertain terms that tweaking the climate by injecting aerosols into the stratosphere would be likely to have drastic and unpredictable effects.  "Even when simulations of SAI in climate models are sophisticated, they're necessarily going to be idealized," said Faye McNeill, who co-authored the paper.  "Researchers model the perfect particles that are the perfect size.  And in the simulation, they put exactly how much of them they want, where they want them.  But when you start to consider where we actually are, compared to that idealized situation, it reveals a lot of the uncertainty in those predictions.  There are a range of things that might happen if you try to do this -- and we're arguing that the range of possible outcomes is a lot wider than anybody has appreciated until now."

The climate shows sensitive dependence on initial conditions -- a phrase that will be familiar to anyone who has read about chaos theory.  The one thing that is almost certain is that something like SAI wouldn't cool the planet smoothly and uniformly, leaving other factors (like rainfall patterns) unchanged.  Models showed a chaotic response to injection, often resulting in effects like disruption of tropical monsoons, alteration in the position of jet streams (thus changing storm track patterns), and uneven and rapidly-fluctuating shifts in temperature.

Not good.  As Robert Burns said, "The best laid plans of mice and men gang aft agley."

Basically: we do not understand climate well enough to do this with confidence.  After all, we're in the current mess because we ignored the scientists (starting with Svante Arrhenius in 1896) who said that atmospheric carbon dioxide levels were directly correlated with global average temperature, and that therefore we were going to warm the planet by burning fossil fuels.  Let's not ignore the ones now who are saying, correctly, that blowing aerosols up into the stratosphere and hoping for the best is a bad, bad idea.

My fear, though, is that the current regime here in the United States has the motto "quick fixes and short-term expediency FTW," so they'll think this is just a nifty idea.

To return to my original point, despite the best work of scientists, our knowledge is still incomplete, and that applies especially to complex, chaotic systems like the climate.  The climatologists themselves know this, and thank heaven a group of them have published a paper urging us to (extreme) caution.  

Let's hope the people in power are, for once, listening.

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The collapse

You've undoubtedly heard British philosopher Thomas Hobbes's famous quote that in the past, our forebears' lives were "nasty, poor, brutish, and short."  That's certainly true in my ancestors' case, given that just about all of them were poverty-stricken French and Scottish peasants who uprooted and came over to North America because they thought for some reason it would be lots better to be poverty-stricken peasants over here.

I've had at least some inkling about how difficult life was back then since my history classes in college, but it was always in a purely academic way.  While my parents weren't wealthy by any stretch, we never wanted for food on the table, and any struggles they had paying the bills were well hidden and not talked about.  As an adult, I went through a long period in my life when I was the sole member of the family with a paying job, and it was scary to think that if I'd lost it, we would have been screwed; but I never really was in any danger of that.  As long as I kept showing up to school every day and teaching my classes with a reasonable level of competence, I could count on being able to pay the mortgage.

Hundreds of years ago, though, that simply wasn't true for the vast majority of humanity.  I think what really brought home to me the precarious existence most people led was when I read the book The Little Ice Age: How Climate Made History by Brian Fagan (which I highly recommend).  For most of human history, people have literally been one bad harvest season from starvation and one sudden epidemic from being wiped out en masse.  All it took was a single prolonged drought, early frost, or extended period of cool, rainy weather spoiling the crops, and people had nothing to fall back on.

No wonder so many of them were superstitious.  It's easy to put your faith in magical thinking when your lives hinge on a set of conditions you don't understand, and couldn't control even if you did.

What is striking, though, is how insulated the leaders of countries have always felt from the effects of all of this -- often to the extent of ignoring them completely.  There's an argument to be made that it was a series of weather-related poor harvests that lit the tinder box in the French Revolution (and many of the leaders didn't find out their mistake until they were being led to the guillotine).  But to take a less well-known example, let's look at a paper that came out last week in the journal Science Advances about a different civilization, the fascinating Classical Mayan culture, which lasted over six hundred years -- from about 250 to 900 C. E. -- completely dominating the Yucatán Peninsula in southern Mexico and northern Central America before collapsing with astonishing speed.  Cities were abandoned to the jungle, the elaborate building and carving stopped entirely, and the entire region went largely silent until the rise of the city of Mayapan in the twelfth century.

[Image licensed under the Creative Commons User:PhilippN, Calakmul - Structure I, CC BY-SA 3.0]

Scientists from the University of Cambridge did a study of the chemical composition of the oxygen isotope ratios in the limestone deposited on stalagmites in caves in the northern Yucatán, which can be read in layers like tree rings.  Oxygen isotope ratios are a good proxy for rainfall; oxygen-18:oxygen-16 ratios tend to drop during the rainy season, so an overall low 18:16 ratio is a strong signal of drought.

And what the scientists found was that during the time between 871 C.E. and 1021 C.E. there was a severe thirteen-year drought, and three shorter (five to six year) droughts.  Water supplies dried up, crops failed, trade stopped, and the inevitable happened -- the common people blamed their leaders.  Violent revolution ensued, and in the end, a civilization that had dominated the region for centuries collapsed completely.

It's easy to think something like this couldn't happen to us, but right now we're in the middle of one of the most dramatic climate shifts on record, with global average temperatures rising faster than they did during the terrifying Paleocene-Eocene Thermal Maximum, 55 million years ago.  And you know what the Trump regime's response to this is?

Just last week they announced plans to deliberately destroy the Orbiting Carbon Observatory, one of our chief climate monitoring satellites.  Not because it's malfunctioning; it's working fine.  Not because it costs lots of money; it's already paid for.

No, the reason they want to destroy the satellite is the same as the reason they stopped keeping track of new COVID cases during the height of the pandemic.  If you don't measure something, you can pretend it's not happening.

Destroying the OCO won't stop the effects of anthropogenic climate change, of course.  It'll just prevent us from seeing them coming.

So I may have misspoken at the beginning, in leading you to believe that our ancestors were any different from us with regards to the fragility of our existence -- and the tendency to fall back on unscientific thinking.  But let us hope that the ignorance and greed of our current elected officials won't return us to another era of nasty, poor, brutish, and short lives, where the risk of starvation was never far away.  

This time, though, if it happens it won't be an unfortunate result of living in a world we don't understand.  It will be a self-inflicted wound caused by trusting power-hungry people who know perfectly well what they are doing, but value short-term expediency over the long-term habitability of the planet.

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Halting the conveyor

Today we have three stories that are absolutely horrifying in juxtaposition.

The first is a paper that came out a couple of days ago in Nature, describing a study by Jade Bowling (of Lancaster University) et al.  It is an analysis of a strange and sudden change in the topography of the Greenland Ice Sheet that happened in 2014 -- a two-square-kilometer part of the sheet dropped by as much as eighty-five meters.  The question, of course, is what happened to all the ice that used to be underneath it.  And what Bowling et al. found was that it had melted -- that the underside of the Greenland Ice Sheet is riddled with subglacial lakes and rivers.  In this case, downstream of the collapsed region, a flood burst through the surface, and within ten days ninety million cubic meters of fresh water gushed out as the cavity emptied.

We usually think of the melting of the polar ice sheets as a gradual process, something like the way ice cubes slowly melt in your glass of tea in summer.  But what this study shows is that the process proceeds quietly -- until it doesn't.  The tipping point between a gentle trickle and a massive flood can occur suddenly, and be due to factors that are largely out of sight.

The second came out in the same issue of Nature, and has to do with a study of the paleoclimate by a team led by Pedro DiNezio of Colorado University - Boulder.  DiNezio and his collaborators looked at the Atlantic Meridional Overturning Circulation (AMOC), sometimes called the "Atlantic Conveyor."  The AMOC is an enormous ocean current, of which the Gulf Stream is only a part, moving a greater volume of water per second than all of the rivers of the world put together.  It is driven by the combined effects of evaporation (making the water saltier) and cooling as the current flows northward; both of these result in the water becoming denser, and south of Iceland it becomes dense enough to sink.  This draws more warm water northward -- and is why Ireland and the United Kingdom, which are on the same latitude as Alberta, have mild climates.

[Image licensed under the Creative Commons R. Curry, Woods Hole Oceanographic Institution/Science/USGCRP., OCP07 Fig-6, CC BY 3.0]

But freshwater intrusion, like the one the prior study considered, lowers the density of the surface water, eventually making it too fresh to sink.  This can slow down -- or halt entirely -- the AMOC.

The focus of the effects has usually been on northeastern North America and northwestern Europe, where that heat transfer slowdown would be expected to trigger a dramatic cooling similar to the sudden crash that initiated the Younger Dryas 12,900 years ago, during which a warming climate was plunged back into the freezer for over a thousand years.  But what the DiNezio et al. study considered was what happens to all that excess heat.  Just because we here in upstate New York would probably be freezing our asses off doesn't mean the rest of the world would be.  The heat energy, of course, doesn't just go away.

And what they found is that when the AMOC slows down, that heat remains in the tropics -- triggering a spike in temperature and a drop in rainfall near the equator.  "This is bad news, because we have these very important ecosystems in the Amazon," said DiNezio.  "The Amazon rainforest contains almost two years of global carbon emissions, making it a major carbon sink on Earth.  Drought in this region could release vast amounts of carbon back into the atmosphere, forming a vicious loop that could make climate change worse."

But of course, no story about climate change would be complete without some breaking news describing how the Trump administration is determined to make it worse.  Lee Zeldin, head of the Environmental Protection Agency (which should have its name changed to the Big Oil Protection Agency, because under his leadership they couldn't give a flying rat's ass about protecting the environment), has just announced the overturning of a 2009 declaration stating that carbon dioxide and other greenhouse gases endanger human health and welfare.

His justification?  What do you think it was?

"It cost Americans a lot of money," Zeldin said.

The declaration was the foundation of climate change regulation in this country, and the impetus for rules limiting emissions from cars, airplanes, and power plants.  If the "endangerment finding," as the declaration is called, is overturned. it gives corporations carte blanche to ignore previous guidelines and mandates.

Zeldin, of course, thinks this is just hunky-dory.  "This will be the largest deregulatory action in the history of America," he crowed.

Because short-term profit is apparently more in need of attention than the long-term habitability of the planet.

I wish I had a hopeful note to end on, but I don't.  The whole thing puts me in mind of a comment from a student in my Environmental Science class, maybe fifteen years ago.  The question I put to them was, "At what point do you think that the majority of Americans will be motivated to address climate change in a meaningful way?"

Her answer was, "It won't happen until average Americans are directly and harshly impacted by it.  When there's no food on the shelves in the grocery stores.  When the rivers dry up.  When the sea level rises enough to flood major coastal cities.  Until then, it's easier to pretend nothing's wrong."

Another student, aghast, said, "But won't it be too late at that point?"

She responded simply, "Of course it will."

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The collapse

A couple of weeks ago, I wrote about the spike in atmospheric oxygen concentration -- by some estimates, rising to 35% -- during the Carboniferous Period, triggered by explosive growth of forests, and allowing arthropods like insects, arachnids, and millipedes to grow to enormous sixes.

The good times, though (for them at least), were not to last.  Around three hundred million years ago, there was a sudden drop in oxygen and rise in carbon dioxide.  This triggered rapid climatic shifts that resulted in the Late Carboniferous Rain Forest Collapse, which saw a major alteration from the swamp-dwelling plants and animals at the height of the period to species that could tolerate the dry heat that was to persist throughout the next period, the Permian.  (This set up the rise of reptiles, which would see their peak in the dinosaurs of the Mesozoic.)

Artist's depiction of the mid-Carboniferous swamps (ca. 1887) [Image is in the Public Domain]

The source of the excess carbon dioxide was very likely volcanic.  Besides the fact that lava can contain dissolved gases (mostly carbon and sulfur dioxide), the heat of the eruptions may have caused the oxidation of the plentiful limestone and coal deposits formed during the earlier lush, wet part of the period -- a precursor of the much bigger disaster that was in store fifty million years later, when at the end of the Permian, the Siberian Traps erupted and tore through a huge amount of the sequestered carbon, causing widespread global anoxia and climate change, and the largest mass extinction ever.

By some estimates, ninety percent of life on Earth died.

But the rain forest collapse at the end of the Carboniferous was bad enough.  A study that came out this week in Proceedings of the National Academy of Sciences found the anoxia/hypoxia hit the oceans the hardest, where the oxygen levels rapidly dropped by between four and twelve percent, with a commensurate rise in dissolved carbon dioxide.  When carbon dioxide dissolves in water, it produces a weak acid -- carbonic acid -- lowering the pH.  Organisms that make their shells out of calcium carbonate, like mollusks, brachiopods, and corals, literally dissolved.

You ready for the kicker?

The study's estimate of the rate of carbon dioxide release during the Late Carboniferous Rain Forest Collapse is a hundred times smaller than the rate we're putting carbon dioxide into the atmosphere today through burning fossil fuels.

"This is a huge discovery, because how do you take an ocean sitting under an atmosphere with much more oxygen than today and permit this?" said Isabel Montañez of the University of California - Davis, senior author of the study.  "The message for us is, 'Don't be so sure that we can't do this again with our current human-driven release of carbon dioxide.'"

The problem is, the current administration is in the pockets of the fossil fuel industry, and is doing their level best to pretend this isn't happening, and to discredit anyone who says it is.  Worse, actually; they've cancelled funding for any scientific research about climate.

Because apparently "la la la la la la not listening" is now considered wise political policy.  This, despite warning signals like the eastern half of the United States sweltering this past week under the most extreme heat wave we've had in over fifty years.

So I'm expecting studies like the one released this week by Montañez et al. to receive exactly zero attention from the people who actually could work toward addressing this situation.  It brings to mind a quote from Upton Sinclair, uttered almost a century ago: "It is difficult to get a man to understand something when his salary depends on his not understanding it."

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Thawing the snowball

One of the frightening things about a system in equilibrium is what happens when you perturb it.

Within limits, most systems can recover from perturbation through some combination of negative feedbacks.  An example is your body temperature.  If something makes it goes up -- exercise, for example, or being outside on a hot, humid day -- you sweat, bringing your temperature back down.  If your body temperature goes down too much, you increase your rate of burning calories, and also have responses like shivering -- which brings it back up.  Those combine to keep your temperature in a narrow range (what the biologists call homeostasis).

Push it too much, though, and the whole thing falls apart.  If your temperature rises beyond about 105 F, you can experience seizures, convulsions, brain damage -- or death.  Your feedback mechanisms are simply not able to cope.

This, in a nutshell, is why climate scientists are so concerned about the effects of anthropogenic carbon dioxide.  Within limits -- as with your body temperature -- an increase in carbon dioxide results in an increase in processes that remove the carbon dioxide from the atmosphere, and the whole system stays in equilibrium.  There is a tipping point, however.

The problem is that no one knows where it is -- and whether we may have already passed it.

A piece of research from the Virginia Polytechnic Institute, however, has suggested that this flip from stability to instability may be fast and unpredictable.  A paper authored by a team led by paleobiologist Shuhai Xiao, that was published in the journal Geology, looks at one of the main destabilization events that the Earth has ever experienced -- when the "Snowball Earth" thawed out in the late Precambrian Period, 635 million years ago.

Artist's conception of the Precambrian Snowball Earth [Image is in the Public Domain, courtesy of NASA/JPL]

Xiao and his team studied rocks from Yunnan and Guizhou, China, that are called cap carbonates.  They are made of limestone and dolomite and are deposited quickly in marine environments when the carbon dioxide content of the atmosphere spikes, leading to a dramatic temperature increase and a subsequent increase in absorption of carbonates into seawater (and ultimately deposition of those carbonates on the seafloor).  The cap carbonates Xiao et al. studied were dated to between 634.6 and 635.2 million years old, which means that the entire jump in both temperature and carbon dioxide content took less than 800,000 years.

So in less than a million years, the Earth went from being completely covered in ice to being subtropical.  The jump in global average temperature is estimated at 7 C -- conditions that then persisted for the next hundred million years.

Xiao et al. describe this as "the most severe paleoclimatic [event] in Earth history," and that the resulting deglaciations worldwide were "globally synchronous, rapid, and catastrophic."

Carol Dehler, a geologist at Utah State University, is unequivocal about the implications.  "I think one of the biggest messages that Snowball Earth can send humanity is that it shows the Earth’s capabilities to change in extreme ways on short and longer time scales."

What frustrates me most about today's climate change deniers is that they are entirely unwilling to admit that the changes we are seeing are happening at an unprecedented rate.  "It's all natural," they say.  "There have been climatic ups and downs throughout history."  Which is true -- as far as it goes.  But the speed with which the Earth is currently warming is faster than what the planet experienced when it flipped between an ice-covered frozen wasteland and a subtropical jungle.  It took 800,000 years to see an increase of the Earth's average temperature by 7 degrees C.

The best climate models predict that's what we'll see in two hundred years.

And that is why we're alarmed.

It's unknown what kind of effect that climate change in the Precambrian had on the existing life forms.  The fossil record just isn't that complete.  But whatever effect it had, the living creatures that were around when it happened had 800,000 years to adapt to the changing conditions.  What's certain is that an equivalent change in two centuries will cause massive extinctions.  Evolution simply doesn't happen that quickly.  Organisms that can't tolerate the temperature fluctuation will die.

We can only speculate on the effects this would have on humanity.

This is clearly the biggest threat we face, and yet the politicians still sit on their hands, claim it's not happening, that remediation would be too costly, that we can't prevent it, that short-term profits are more important than the long-term habitability of the Earth.  (Not to mention firing the people and closing the agencies that are currently trying to do something about it.)  Our descendants five hundred years from now will look upon the leaders from this century as having completely abdicated their responsibility of care for the people they represent.

Presuming we still have descendants at that point.

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Whiplash

Like many people, I've been watching the news, photographs, and video footage coming in from the fires in the Los Angeles region with feelings of absolute horror.

[Image licensed under the Creative Commons Toastt21, PalisadesFire fromDowntown, CC BY-SA 4.0]

As of the time of this writing, ten people have died, 34,000 acres have burned, and 200,000 people are under mandatory evacuation orders.  At least ten thousand structures -- homes and businesses -- have burned to the ground.  And while the high winds that have been driving the spread of the wildfires and making fighting them difficult to impossible are supposed to moderate this weekend, meteorologists have predicted them to increase again early next week.

Because there's no human tragedy so heartwrenching that Donald Trump won't use it to score political points, he's gone on Truth Social repeatedly in the last couple of days to say the whole thing is Governor Gavin "Newscum"'s fault, presumably for not raking the forests or going up to Canada to turn on the "very large faucet" that is holding back all the water from the western half of the United States.  Not a word of empathy for the people who've had their homes and their livelihoods destroyed, not a mention of the scale of this catastrophe.

It's what we've come to expect from leaders who have zero compassion and no benchmarks for conduct except for profit, cronyism, and revenge.

Note, too, that there's been no mention that the ultimate cause of this disaster is anthropogenic climate change.  No, gotta find a way that the Democrats are to blame, even though we've been the ones who have been warning about this for years.  In fact, just this week a study was published in the journal National Review of the Earth and the Environment that directly attributes the risk of devastating fire outbreaks to climate change -- more specifically, to a phenomenon called hydroclimate whiplash.

One of the results of global warming that is hard to get people to understand is that it isn't uniform.  The entire world isn't going to gradually slide into becoming a tropical rain forest.  The polar vortex phenomenon we've seen here in the northeastern United States over the last few years is actually one of the predictions of climate change models; the overall warming of the Earth causes a weakening of the polar jet stream, causing it to meander like a river crossing a flat plain.  Loops of the jet stream are pushed south, and those meanders allow icy polar air to move much farther south than normal.  So these deep cold snaps are actually caused by anthropogenic climate change; they're not an argument against it.

Likewise, rainfall and snowfall patterns aren't going to move uniformly in one direction, they're expected to fluctuate wildly.  This is hydroclimate whiplash, and is at the root of the Los Angeles fires.  The rainy season in early 2024 in southern California was abnormally wet (in fact, there were multiple damaging mudslides caused by what are called "atmospheric rivers" dumping huge quantities of rain and snow).  This triggered explosive growth in fast-growing plants like grasses and annual and perennial weeds.  The summer that followed was abnormally dry, and the winter 2024-2025 rainy season basically hasn't happened yet.  So you had what amounted to a tinder box of dried-up plants, just waiting for a spark to start the conflagration.

"The global consequences of hydroclimate whiplash include not only floods and droughts, but the heightened danger of whipsawing between the two, including the bloom-and-burn cycle of overwatered then overdried brush, and landslides on oversaturated hillsides where recent fires removed plants with roots to knit the soil and slurp up rainfall," said Daniel Swain, climatologist with UCLA, who co-authored the study.  "Every fraction of a degree of warming speeds the growing destructive power of the transitions."

You won't hear a word of this from Donald Trump and his cronies, of course.  Not while they have Joe Biden and Gavin Newsom to blame, and certainly not as long as the GOP is in the pockets of the fossil fuels industry.  Trump's pronouncements on the wildfires have contained, to quote CNN's Daniel Dale, a "staggering amount of wrongness," but I guess now we're back to living in the "alternative facts" world we were in from 2016 to 2020.

Since we've now lost our opportunity here in the United States to put the brakes on fossil fuel use, at least for the next four years, look for more extremes to come.  We can expect bigger storms, more heat waves and polar vortexes, more atmospheric rivers and catastrophic droughts.  We tried to warn people; hell, I've been writing about this topic here for fifteen years, and was discussing it in my classes three decades ago.

Not that the people in charge were listening.  As Upton Sinclair put it, "It is difficult to get a man to understand something when his salary depends on his not understanding it."

So there's nothing we can do now but to put pressure on legislators -- frustrating though that's likely to be in the current political climate -- and prepare our own selves for weathering the storms, literal and figurative.  Find places to donate to help those displaced by the fires, some of whom have lost everything.  (Here's just one of many options.)  

Most importantly to the bigger picture: keep speaking up against the lies coming from Trump and his allies.  We can't let misinformation shout more loudly than the truth.

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NEW!  We've updated our website, and now -- in addition to checking out my books and the amazing art by my wife, Carol Bloomgarden, you can also buy some really cool Skeptophilia-themed gear!  Just go to the website and click on the link at the bottom, where you can support your favorite blog by ordering t-shirts, hoodies, mugs, bumper stickers, and tote bags, all designed by Carol!

Take a look!  Plato would approve.

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