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."

****************************************

Dry times

If I asked you to name the driest spots on Earth, I wonder if this one would come to mind -- even though it's a top contender for the number one spot.

You might have thought of Chile's Atacama Desert, or possibly somewhere in the Gobi, Sahara, or the Rub' al Khali (Empty Quarter) of Saudi Arabia.  All good guesses, and certainly they're not what I'd call wet climates.  In fact, parts of the Atacama come in second; the high elevation and perpetual clear skies are why it's such a great spot for astronomical observatories -- it's currently home to three of the best, and a fourth is being built.  The La Silla Observatory, the Paranal Observatory (which includes the Very Large Telescope), the Llano de Chajnantor Observatory (which hosts the ALMA international radio observatory), and the Cerro Armazones Observatory (site of the future Extremely Large Telescope), are all in the Atacama Desert.

As an aside, can astronomers please try to come up with better names for their observatories?  I mean, what the hell?  The "Very Large Telescope" and the "Extremely Large Telescope"?  What's next, the "Abso-fucking-lutely Humongous Telescope, No Really I'm Totally Serious You Won't Believe How Big It Is"?

Probably not.  AflHTNRITSYWBHBII would be hard to fit on a grant application.

But I digress.

Anyhow, the top spot for the driest climate on Earth is the McMurdo Dry Valley region of Antarctica, and beats most of the other possibilities by a significant margin.  Some studies indicate the place hasn't had any significant accumulated precipitation in over two million years.  What small amount does fall -- estimates are in the range of a hundred millimeters per year -- almost all evaporates before it reaches the ground because of the fierce katabatic winds.  Katabatic winds occur because air density is strongly dependent upon temperature, and the McMurdo Dry Valleys are surrounded by mountains.  Air masses above the mountaintops lose heat faster, making them become more dense; the air then flows downhill, easily reaching hurricane speed, and pools in the valleys.  Most of the air already started out dry; any humidity it originally had was precipitated out as snow on the windward side of the mountains.  This drops the relative humidity to only a few percent and keeps it there.

Any snowflakes falling into that don't stand a chance.  They don't melt; it's too cold for that.  They sublimate -- turn from a solid to a gas without passing through the liquid phase.

That's how cold and dry it is.

The result is that the McMurdo Dry Valleys are basically nothing but a vast expanse of extremely cold rock, gravel, and sand.

[Image licensed under the Creative Commons Dturme, Labyrinth, Wright Valley, McMurdo Dry Valleys, Antarctica, CC BY-SA 4.0]

The exposed rocks are mostly of Triassic age, and belong to the Beacon Formation, which is largely made of sandstone.  There are a few volcanic intrusions only a few million years old, but by and large, the whole place is just one big bunch of very old wind-eroded sandstone, quartzite, and pebble conglomerate.

And yet... there are living things there.

Not many, of course, but the McMurdo Dry Valleys are home to endolithic bacteria, which live in the cracks and fissures inside rocks, subsisting on the minerals therein and the tiny amount of water in the soil (supplemented from time to time by trickles of glacial meltwater).  They're still poorly understood, but are thought to be metabolically similar to the mid-ocean vent bacteria, which are able to use minerals like sulfur, iron, and manganese as the basis of their metabolism.

All of which makes me wonder if Mars hosts life.  McMurdo has been described as "the most Mars-like environment on Earth;" the site has been used to test equipment for the Mars rover missions.  Hell, if bacteria can survive in McMurdo, it's not much of a stretch to surmise that there might be life underground on Mars -- perhaps a holdover from the distant past, when Mars was a much warmer, wetter place.

I find places like this fascinating.  The idea that we have here on our (mostly) temperate and green planet a spot so profoundly inhospitable is pretty astonishing.  I wonder how (or if) climate change will alter things there?  The entire continent is climatically isolated by the Antarctic Circumpolar Current, one of the hugest oceanic water transporters in the world -- the amount of water flowing through the Drake Passage, between South America and Antarctica, is estimated at around 130 times the volume of all the world's rivers put together -- so it's hard to imagine this shifting in any significant way.

But given that many oceanographers fear that meltwater from Greenland is going to block the Atlantic Meridional Overturning Circulation -- the best-known part of which is the Gulf Stream -- maybe I shouldn't speak too soon.

So that's our look at the Earth's answer to Mars.  Not, I'm afraid, a locale I'm eager to visit, given how little I like the cold.  I'm adventurous, but I draw the line at a place that hostile.

Plus, I like rocks as much as the next guy, but when there's nothing else to see -- well, I can think of a few other places that are higher on the destinations list.  I'm content to appreciate McMurdo from afar.

****************************************

Wipeout

252 million years ago, the Earth was hit by a confluence of Very Unfortunate Events.

First, most of the large continental land masses locked up into a single supercontinent, Pangaea.  This had multiple effects, including alterations of oceanic currents, massive desertification, and the collapse of the convection cells powering seafloor spreading at mid-ocean ridges.  The latter caused a drastic lowering of sea level and exposure of continental shelves, reducing habitat for marine species that live in shallow water (which is most of them).

Second, the tinder box that had formed in the Carboniferous Period -- enormous deposits of coal, oil, and limestone produced when the Earth was basically one giant greenhouse -- found its lit match when the Siberian Traps erupted.  This is one of the largest volcanic events known, and produced an almost unimaginable four million cubic kilometers of basaltic lava.  This ripped through all that coal and carbonate rock, releasing catastrophic amounts of carbon dioxide and sulfur dioxide into the atmosphere.  The portion of the excess absorbed into the ocean caused acidification, killing any marine animal with carbonate shells or skeletons.  The resulting temperature rise caused worldwide oceanic anoxia.  It very likely also triggered the unraveling of unstable methane clathrate deposits on the seafloor, releasing gaseous methane and further boosting the temperature.

If that weren't enough, right around this time the Araguainha Impactor hit what is now Brazil.  The spot where it struck was at the time mostly composed of another gift from the Carboniferous -- oil shale.  This was flash-incinerated, releasing yet more carbon dioxide.

The result: the extinction of between 80% and 95% of the species on Earth, depending on how you count them and who you ask.  

What there's no doubt of, though, is that it was devastating.  It's the closest the Earth has come to undergoing a complete wipeout.  Entire taxa went extinct, including eurypterids (sea scorpions), trilobites, blastoids, tabulate and rugose corals, and acanthoid fish; 99% of radiolarian species vanished, as well as 98% of gastropods and 97% of ammonites and foraminiferans.  The entire food web collapsed.

Afterward, the Earth was an overheated, sulfur-smelling, hypoxic, largely lifeless wasteland.

And yet, somehow, it recovered.  How exactly the Earth's living things made it through the largest bottleneck ever is the subject of a paper last week in the Geological Society of America Bulletin, authored by a team from University College Cork, the University of Connecticut, and the Natural History Museum of Vienna.  And what it found was that the bounce-back didn't happen all at once.  It was far from a linear progression toward rebuilding the biosphere -- there were further shifts and setbacks over several million years as life "found a way."

The team focused mainly on the plants, given that they're the base of the food web.  Some of the first recolonizers were conifers, but they suffered a reversal not even a million years after the main pulse of extinctions with the Smithian-Spathian Boundary Event, a further spike in global temperature that ultimately saw sea surface temperatures of 40 C (104 F), but which was then followed by an unexplained and equally rapid drop.  The wild pendulum swings in temperature caused the collapse of the resurgent coniferous forests; ultimately they were replaced by seed ferns and club mosses (the latter were larger than the ones we have today, but not as big as the enormous Lepidodendrons that were around during the Carboniferous).  

An early Triassic seed fern, Lepidopteris [Image licensed under the Creative Commons Vivi Vajd, Stephen McLoughlin, Sam M. Slater, Ola Gustafsson, Allan G. Rasmusson, Lepidopteris life restoration, CC BY 4.0]

Eventually the climate stabilized, but any way you spin it, the Early Triassic Period was a horrible time to be alive.  It was largely hot and dry, but then -- with startling rapidity -- terrestrial biomes were swamped during the weird Carnian Pluvial Episode, a two-million-year-long thunderstorm which I wrote about not long ago.  Then, at the end of the Triassic, there was yet another massive extinction, this one probably caused by the volcanism from the Central Atlantic Magmatic Province (which would ultimately open the Atlantic Ocean).  Things had largely settled down by the beginning of the Jurassic Period, at which point we were heading into a period of lush forests and (mostly) stable climate -- the long, glorious Age of Dinosaurs.

But as you know, even their salad days weren't destined to last forever.

It always strikes me, when I read papers like this one -- the colossal hubris and ignorance of people who think we can mess around with Earth's ecosystems with complete impunity.  They often shrug off any Cassandras with breezy lines like, "The Earth's climate has had swings in the past, and has always recovered."  And in one sense, sure, that's true.  Faced even with a catastrophic extinction like the Permian-Triassic, enough species made it through the bottleneck -- and the whipsawing that happened afterward, as the climate gradually restabilized -- to repopulate the Earth.

But keep in mind that a great many species didn't make it.  Most of them, in fact.  Then, at the end of the Cretaceous, the non-avian dinosaurs -- that had been the dominant group worldwide for two hundred times longer than humans have existed -- were completely eliminated.  Okay, life recovered once again, but even for the survivors, living through the event itself was no fun.

Oh, and allow me to put this whole grim story into perspective by mentioning the second paper that came out this week; a huge study out of James Cook University and the University of Adelaide showing unequivocally that tropical forests are dying off because of human-induced climate change -- that they're not adapting fast enough to cope with how quickly we're altering the climate.

We are the first species that has sufficient brainpower to understand how our actions affect the biosphere, and (perhaps) enough power to work toward mitigating them.  And instead, we're largely doing nothing, selling out the future in exchange for short-term expediency, a use-it-once-then-throw-it-away lifestyle, and enriching the coffers of corporate billionaires.  The current so-called administration's mottos with regards to the environment are "Deregulate everything," "Cut down more trees," and "Drill, baby, drill."

They, and all of us, should remember: sure, it's likely that whatever we do, in a million years there still will be plenty of life on Earth.  No matter the mistakes we make, the biosphere will survive.

But there is no guarantee that the survivors will include us.

****************************************

The riddle of the sun stones

When you think about it, it's unsurprising that our ancestors invented "the gods" as an explanation for anything they didn't understand.

They were constantly bombarded by stuff that was outside of the science of their time.  Diseases caused by the unseen action of either genes or microorganisms.  Weather patterns, driven by forces that even in the twenty-first century we are only beginning to understand deeply, and which controlled the all-important supply of food and water.  Earthquakes and volcanoes, whose root cause only began to come clear sixty years ago.

Back then, everything must have seemed as mysterious as it was precarious.  For most of our history, we've been at the mercy of forces we didn't understand and couldn't control, where they were one bad harvest or failed rainy season or sudden plague from dying en masse.

No wonder they attributed it all to gods and sub-gods -- and devils and demons and witches and evil spirits.

As much as we raise an eyebrow at the superstition and seeming credulity of the ancients, it's important to recognize that they were no less intelligent, on average, than we are.  They were trying to make sense of their world with the information they had at the time, just like we do.  That we have a greater knowledge base to draw upon -- and most importantly, the scientific method as a protocol -- is why we've been more successful.  But honestly, it's no wonder that they landed on supernatural, unscientific explanations; the natural and scientific ones were out of their reach.

The reason this comes up is a recent discovery that lies at the intersection of archaeology and geology, which (as regular readers of Skeptophilia know) are two enduring fascinations for me.  Researchers excavating sites at Vasagård and Rispebjerg, on the island of Bornholm, Denmark, have uncovered hundreds of flat stone disks with intricate patterns of engraving, dating from something on the order of five thousand years ago.  Because many of the disks have designs of circles with branching radial rays extending outward, they've been nicknamed "sun stones."  Why, in around 2,900 B.C.E., people were suddenly motivated to create, and then bury, hundreds of these stones, has been a mystery.

Until now.

[Image credit: John Lee, Nationalmuseet, Copenhagen, Denmark]

Data from Greenland ice cores has shown a sudden spike in sulfates and in dust and ash from right around the time the sun stones were buried -- both hallmarks of a massive volcanic eruption.  The location of the volcano has yet to be determined, but what is clear is that it would have had an enormous effect on the climate.  "It was a major eruption of a great magnitude, comparable to the well-documented eruption of Alaska’s Okmok volcano in 43 B.C.E. that cooled the climate by about seven degrees Celsius," said study lead author Rune Iversen, of the Saxo Institute at the University of Copenhagen.  "The climate event must have been devastating for them."

The idea that the volcanic eruption in 2,900 B.C.E. altered the climate worldwide got a substantial boost with the analysis of tree rings from wood in Europe and North America.  Right around the time of the sulfate spike in the Greenland ice cores, there's a series of narrow tree rings -- indicative of short growing seasons and cool temperatures.  Wherever this eruption took place, it wrought havoc with the weather, with all of the results that has on human survival.

While the connection between the eruption and the sun stones is an inference, it certainly has some sense to it.  How else would you expect a pre-technological culture to respond to a sudden, seemingly inexplicable dimming of the sun, cooler summers and bitter winters with resultant probable crop failures, and even the onset of wildly fiery sunrises and sunsets?  It bears keeping in mind that our own usual fallback of "there must be a scientific explanation even if I don't know what it is" is a relatively recent development. 

So while burying engraved rocks might seem like a strange response to a climatic change, it is understandable that the ancients looked to a supernatural solution for what must have been a mystifying natural disaster.  And we're perhaps not so very much further along, ourselves, given the way a substantial fraction of people in the United States are responding to climate change even though the models have been predicting this for decades, and the evidence is right in front of our faces.  We still have plenty of areas we don't understand, and are saddled with unavoidable cognitive biases even if we do our best to fight them.  As the eminent science historian James Burke put it, in his brilliant and provocative essay "Worlds Without End":

Science produces a cosmogony as a general structure to explain the major questions of existence.  So do the Edda and Gilgamesh epics, and the belief in Creation and the garden of Eden.  Myths provide structures which give cause-and effect reasons for the existence of phenomena.  So does science.  Rituals use secret languages known only to the initiates who have passed ritual tests and who follow the strictest rules of procedure which are essential if the magic is to work.  Science operates in the same way.  Myths confer stability and certainty because they explain why things happen or fail to happen, as does science.  The aim of the myth is to explain existence, to provide a means of control over nature, and to give to us all comfort and a sense of place in the apparent chaos of the universe.  This is precisely the aim of science.

Science, therefore for all the reasons above, is not what it appears to be.  It is not objectively impartial, since every observation it makes of nature is impregnated with theory.  Nature is so complex, and sometimes so seemingly random, that it can only be approached with a systematic tool that presupposes certain facts about it.  Without such a pattern it would be impossible to find an answer to questions even as simple as "What am I looking at?"

****************************************

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.

****************************************

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.

****************************************

Ignoring Cassandra

The Atlantic Meridional Overturning Circulation (AMOC), sometimes nicknamed "the Atlantic Conveyor," is an enormous oceanic current that not only encircles the entire Atlantic Ocean, it links up with other circulation patterns in the Indian and Pacific Oceans.

[Image is in the Public Domain courtesy of NASA]

It's called a "thermohaline" circulation because it's driven by two things; temperature and salinity.  Cold water is denser than warm water; salty water is denser than fresher water.  Alterations in these factors determine where the water goes, setting up convection (the movement of a fluid because of gradients in density).  Specifically, as the warm Gulf Stream (the red line along the eastern coast of North America on the above map) moves northward, it cools down and evaporates.  Those both act to increase its density, to the point that just south of Iceland, it sinks.

That sinking mechanism is what drives the entire thing.  Slow that down, and the whole system fails.

Which is exactly what is happening.  A paper last week in Nature found that the AMOC has diminished dramatically because of anthropogenic climate change; the warming oceans, along with fresh meltwater from Greenland, has made large parts of the north loop of the circulation too buoyant to sink.  Since 1950, the flow rate has gone down by 0.46 sverdrups.  Before you say, "Well, that doesn't sound like very much," allow me to point out that one sverdrup is a million cubic meters a second.  The combined flow of all the rivers in the world is only about 1.2 sverdrups.

So 0.46 is huge.

Current models indicate that this change is going to have enormous effects on local climates.  Western and northern Europe are likely to get colder; the surface loop of the AMOC is why Iceland, Scotland, and Scandinavia are way warmer than you'd expect given their latitudes.  The southeastern United States and eastern South America will probably become much warmer; the heat energy doesn't just go away because it's not being transported northward and dissipated.  Rainfall patterns, and storm paths and intensity, will certainly change, but how is unknown.

The truth is, we don't know enough to predict exactly what the outcome will be, at least not with any certainty.  We're perturbing a complex global system with about as much caution as a toddler playing in the mud.  But what seems certain is that we have now entered the "Find Out" phase of "Fuck Around and Find Out."

What kills me is we've been warning about this for decades.  British science historian James Burke's prescient documentary After the Warming described the collapse of the AMOC as an outcome of anthropogenic climate change all the way back in 1991.  But instead of listening to the scientists, and brilliant advocates like Burke who bring science to the public notice, more people were swayed by idiots like former Oklahoma Senator James Inhofe, who brought a snowball onto the floor of the United States Senate and basically said, "Hey, it's snowing, so climate change isn't real, hurr hurr hurr durr."

Of course, listening to Inhofe and his ilk is easy.  If you believe him, you don't have to make any changes to your lifestyle.  And we haven't gotten any further in the intervening decades; President-elect Trump has nominated Lee Zeldin for the head of the Environmental Protection Agency and Doug Burgum for Secretary of the Interior, both thoroughgoing climate change deniers who are deep in the pockets of the fossil fuel industry.  (And please, for the love of all that's holy, stop calling them "climate skeptics."  A skeptic respects the evidence.  These people reject a body of evidence that's as high as Mount Everest in the name of profit and short-term expediency.)

Politicians Discussing Global Warming by Isaac Cordal (2011)

I read a serious analysis of Donald Trump's win claiming that one factor was that Americans have a "suspicion of expertise."  That is something that will never, ever make sense to me.  How is it reasonable to say, essentially, "These people know more than I do, so I don't believe them"?  The result is that we now have one of the most powerful countries in the world being run by a cabal of people who are united by two things -- (1) devotion to Donald Trump, and (2) a complete lack of qualifications.  So this distrust of evidence, science, and rationality is only going to get worse -- and will become the motive force in driving policy.

The problem is, though, if you ignore the truth, sooner or later it catches up with you.  And from the recent paper, it appears it's going to be sooner.  Sea level rise is already threatening coastal communities, and there are island nations that will simply cease to exist if if gets much worse.  Extreme weather events are likely to become commonplace.  We're sure to see alterations in climate that will affect agriculture, and in some places, habitability.

As usual, the people creating the problem aren't the ones who are going to get hurt by it -- at least not at first.  But this is an issue that will, ultimately, affect us all.

And lord have mercy, I am tired.  Tired of shouting warnings, tired of citing study after study, tired of arguing from the standpoint of facts and evidence with people determined not to listen to any of it.  I'm not even an actual scientist, just a retired science teacher and blogger, and I feel like I've been sounding the call about this stuff forever; I can't imagine how the actual researchers feel.  It makes me sympathize with Cassandra, from Greek mythology -- who was blessed with the ability to see the future, but cursed to have no one believe her.

I wish I had some sort of hopeful message to end on, but I don't.  I'm not naturally a pessimist, but given the fact that the country I live in just voted in an anti-science, anti-intellectual, anti-academic administration whose motto seems to be "Corporate Profit Über Alles," I don't think we're going to make any progress here for the next four years.  By then, how much more damage will have been done?

As journalist Sheri Fink put it: "Soon after a disaster passes, we tend to turn our eyes away and focus our resources on the day-to-day, rather than on preparing for the rare, but foreseeable and potentially catastrophic disaster.  It's another form of triage, how much we invest in preparing for that, a very important question for public policy.  But... we are such a short-sighted species."

****************************************

Zealotry

Today, we have three stories that are particularly interesting in juxtaposition.

The first one is heartbreaking.  A unique species of cactus, the Key Largo tree cactus (Pilosocereus millspaughii) is now extinct in the Florida Keys.  It's a tall, slender, spiny plant with white, garlic-scented flowers that open at night and are pollinated by bats.

[Image credit: photographer Susan Kolterman]

Once abundant, it has been declining throughout the twentieth century, but took a nosedive at the century's end -- 84% of the surviving plants died between 1994 and 2017.  It still held on with a population of 150 individuals until Hurricane Irma, but the real culprit seems to be saltwater intrusion into the species's habitat.  By 2021 only six remained, and pieces were harvested by botanists for cultivation before the remaining individuals died.

As such, it has become the first species extirpated as the direct result of climate change and rising sea levels.

"We are on the front lines of biodiversity loss," said George Gann, executive director of the Florida Institute for Regional Conservation.

The second story comes out of Copernicus Climate Change Service, the research arm of the European Union's climate monitoring service.  New data released last week showed that for the last twelve months straight, the global average temperature has been 1.5 C higher than the average in pre-industrial times.  Anyone claiming this is some kind of natural warm-up is simply wrong.  There's no other way to say it.  This global temperature spike is orders of magnitude higher than anything we've ever seen before -- to find anything even close, you have to go back to the Paleocene-Eocene Thermal Maximum, 54 million years ago, and even that probably happened at a slower rate than what we're seeing today.

Carlo Buontempo, director of the CCCS, was unequivocal.  "Even if this specific streak of extremes ends at some point, we are bound to see new records being broken as the climate continues to warm," he said.  "This is inevitable unless we stop adding greenhouse gases into the atmosphere and the oceans."

The last story is where it gets ironic -- because Florida Governor Ron DeSantis, who presides over one of the lowest-lying and most vulnerable states in the United States, and the home (well, it was) of the first species to be extirpated because of climate change, just signed a bill that (1) strikes any mention of climate change from state statutes, (2) outlaws offshore wind turbines, and (3) deregulates the use of natural gas.

"We're restoring sanity in our approach to energy and rejecting the agenda of the radical green zealots," DeSantis said.  Probably because that sounds better than "fuck the long-term habitability of the planet, we've got to protect the fossil fuel industry."

We've got an election coming up in November, and the choice couldn't be clearer.  DeSantis (whose term doesn't expire until 2027, unfortunately), and the rest of the GOP, have rejected science, data, and evidence for the sake of short-term expediency and keeping the endorsement of the oil companies.  There's a plethora of other reasons to vote against them; their anti-education stance, the book bans, their targeting of LGBTQ+ people, the horrifying far-right partisanship of the Supreme Court, and their unquestioning support of a presidential candidate who is a convicted felon and sexual abuser, not to mention a compulsive liar.

But this issue affects every single individual on the planet.  If your mind isn't made up yet, then consider that.  Only one party seems to have the slightest concern about addressing the problem of climate change.  Yeah, what they've done thus far hasn't been all that impressive, either, but at least they're not denying it outright and calling the people who care -- and the ones who actually know some science -- "radical green zealots."

I'll choose the ones who are at least making an effort over the science deniers in half a heartbeat.

****************************************

Atmospheric rivers

If I asked you to name the deadliest single-event natural disaster to strike the western half of the United States in recorded history, what would you answer?

If I had to hazard a guess, most people are going to suggest the 1906 San Francisco earthquake.  This was a bad one, no doubt about it; an estimated three thousand people died, and most of the city was destroyed by the quake and the fires that followed it.  Another one that might come to mind is the eruption of Mount Saint Helens in 1980, but that one comes in a distant follower at fifty-seven casualties.

The worst natural disaster in the western United States -- by a significant margin -- is one a lot of people haven't heard of.  In the winter of 1861-1862, an atmospheric river event turned the entire Central Valley of California into an enormous lake, submerging once dry land under as much as ten meters of water.  Over a period of forty-five days, a hard-even-to-imagine three meters of rain fell in the Sierra Nevada Mountains and the surrounding area, draining down into the lowlands far too fast to run off.  Rivers overflowed their banks; some simply vanished under the expanding lake.  Although the middle part of the state bore the worst of it, devastating floods were recorded that year from northern Oregon all the way down to Los Angeles.

The exact death toll will probably never be known, but it's well over four thousand.  That's about one percent of the entire population of the state at the time.

A man named John Carr, writing in his memoir thirty years later, had this to say:

From November until the latter part of March there was a succession of storms and floods... The ground was covered with snow a foot deep, and on the mountains much deeper...  The water in the river ... seemed like some mighty uncontrollable monster of destruction broken away from its bonds, rushing uncontrollably on, and everywhere carrying ruin and destruction in its course.  When rising, the river seemed highest in the middle...  From the head settlement to the mouth of the Trinity River, for a distance of one hundred and fifty miles, everything was swept to destruction.  Not a bridge was left, or a mining-wheel or a sluice-box.  Parts of ranches and miners cabins met the same fate.  The labor of hundreds of men, and their savings of years, invested in bridges, mines and ranches, were all swept away.  In forty-eight hours the valley of the Trinity was left desolate.  The county never recovered from that disastrous flood.  Many of the mining-wheels and bridges were never rebuilt.

Many of the smaller towns never were, either.

Lithograph of K Street, Sacramento, California, in January of 1862 [Image is in the Public Domain]

What seems to have happened is that in rapid succession, a series of narrow plumes of moist tropical air were carried in off the Pacific.  These "atmospheric rivers" can carry an astonishing amount of water -- some of them have a greater flow rate than the Amazon River.  When they cross over land, sometimes they dissipate, raining out over a wide geographical area.  But the West Coast's odd geography -- two mountain ranges, the Coast Range/Cascades and the Sierra Nevada Mountains, running parallel to each other with a broad valley in between -- meant that as those plumes of moisture moved inland, they were forced upward in altitude (twice).  The drop in pressure and temperature as the air rose caused the water to condense, triggering a month-and-a-half-long rain event that drowned nearly the entire middle of the state.

The reason I bring this up is because the geological record indicates the Great Flood of 1861-62 was not a one-off.  These kinds of floods hit the region on the order of once every century or so.

Only now, the Central Valley is home to 6.5 million people.  And one of the predictions of our best models of climate change is that the warm-up will make atmospheric river events more common.

When people think of deadly disasters, they usually come up with obvious and violent ones like earthquakes and volcanoes.  Certainly, those can be horrific; the 1976 earthquake in Tangshan, China killed an estimated three hundred thousand people.  But the two most dangerous kinds of natural disasters, both in terms of human lives lost and property damage, are flooding and droughts -- two opposite sides of the climatic coin, and both of which are predicted to get dramatically worse if we don't somehow get a handle on the scale of fossil fuel burning.

I saw a quip making its way around social media a while back, that every disaster movie and horror flick starts with someone in charge ignoring a scientist.  There's some truth to that.  Unfortunately, we've not been very good at taking that message to heart.  We need to start listening -- and fast -- and learning from the lessons of the past.  Disasters like the Great California Flood will happen again, and now that we've stomped on the climatic accelerator, it will likely be sooner rather than later.

Let's hope we don't close our eyes to the potential for a catastrophe that will dwarf the one of 170 years ago by several orders of magnitude.

****************************************

Altered flow

John McPhee's wonderful book The Control of Nature describes three attempts to alter naturally-occurring geological processes: the shift of the course of the Mississippi River into the Atchafalaya River (which would leave New Orleans without a port); the lava flow from the 1973 eruption of Eldfell Volcano on the Icelandic island of Heimaey, which threatened to seal off the main town's only harbor; and the ongoing problem with landslides in the San Gabriel Mountains of California, which have been exacerbated by people's insistence on building multi-million-dollar homes in steep-sided canyons.

Of the three, only the Icelanders had a success story.  They halted the lava flow by pumping cold seawater onto it, and stopped it before it closed off the harbor completely; the tongue of solidified rock actually created a useful seawall.  The other two were, and still are, drastic failures.  The levee/spillway system in Louisiana, intended to keep the Mississippi in its channel and prevent it from switching over to the Atchafalaya's shorter and more direct path to the Gulf of Mexico, has caused more silting of the channel and subsidence of the land, both of which were direct contributors to the severity of the Hurricane Katrina disaster in 2005.  California still deals with landslides, despite their best efforts to contain them with various slope stabilization devices -- and rich people are still building their mansions right in harm's way.

33% is not a great success rate, but it's pretty reflective of our attempts to control natural processes.  It's not that I'm saying what we do has no effect; the unfortunate part is most of what we've tried hasn't worked, or has actually made the situation more dire.  The obvious example (anthropogenic climate change) is only one of many examples of times we've messed around with things and come off very much the worse.

Although we're unique in the animal world in being able to control our environments to some extent, we're still very much at the mercy of the natural world.  Big, sudden cataclysms -- events like major earthquakes, volcanic eruptions, hurricanes, tornadoes, or floods -- are the most obvious examples, but sometimes slow, gradual processes can alter the course of history just as profoundly.  The fall of the Roman Empire, about which I've written a couple of times recently, may well have been triggered by a climatic shift causing freezing drought in the central Asian steppes, inducing the Huns to migrate west and starting a domino effect of invasions.  Certainly the rising and lowering of sea level as ice ages came and went altered migration patterns; both Australia and the Americas were colonized during periods when the areas now at the bottom of (respectively) the Gulf of Carpentaria and the Bering Sea were dry land.

The idea that climate has been a major driver for history has gone out of vogue, and is sneeringly referred to as "climate determinism" despite the fact that (1) there's no denying the vagaries of climate have had obvious and dramatic effects, and (2) no one has ever claimed that climate was the only thing affecting the course of events.  Consider, for example, some new research out of the University of Southampton that came out in Nature Geoscience this week.

Life in Egypt has always been dicey -- the valley of the Nile is thickly-inhabited, but go more than a few miles east or west from it and you're in marginally-inhabitable desert.  We all learned in elementary school how the ancient Egyptians survived by learning how to manage what are always called the Nile's "life-giving floods" through irrigation channels and catchment basins, but the truth is, all it took was a dry year or two and the entire civilization was in deep trouble.

The situation changed -- for once, for the better -- about four thousand years ago, when the Nile shifted course and created the floodplain around Luxor.

The reason was the same as what John McPhee explains about the Mississippi, but with a happier outcome.  As rivers flow, they pick up sediment, and when they reach the sea and the water velocity slows down, that sediment is deposited on the river bottom.  This raises it, creating an impediment to water flow, slowing down the water further and making it drop more sediment, and so on and so forth.  Eventually the delta becomes impassible, and the water is forced into another channel (unless people step in and try to stop it, like what is happening with dubious success in Louisiana).

In southern Egypt, though, the switch in paths brought the flow of the Nile out over a broad, flat plain that prior to that had been high and dry.  The outflow into the Mediterranean moved east as well, and the outgoing river broke up into dozens of outflow channels.  This proved extraordinarily beneficial to the people living all along the river's northern half.  "The expansion of the floodplain greatly enlarged the area of arable land in the Nile Valley near Luxor (ancient Thebes) and improved the fertility of the soil by regularly depositing fertile silts," said Benjamin Pennington, who co-authored the paper.  "The Egyptian Nile we see today looks very different from how it would have been throughout much of the last 11,500 years.  For most of this time, the Nile was made up of a network of interwoven channels that frequently changed their course.  Around four thousand years ago, the Nile abruptly shifted and there was rapid floodplain aggradation, where the river began depositing large amounts of sediment, building up the valley floor.  This created a more expansive and stable floodplain."

The result was that the New Kingdom -- which included the reigns of famous pharaohs such as Ahmose I, Hatshepsut, Thutmose III, Amenhotep III, Akhenaten, and Tutankhamun -- had the resources to become one of the significant political powers of the region.

[Image licensed under the Creative Commons Mohammed Moussa, Ramses II in Luxor Temple, CC BY-SA 3.0]

Like McPhee's one-out-of-three success rate for humans trying to control nature, however, it bears keeping in mind that for every example of a natural event benefitting humans, there's one that didn't turn out so well for us.  The collapse of classical Mayan civilization in the eighth century C.E. was largely triggered by a prolonged drought; the onset of the Little Ice Age in the fourteenth created a perfect storm of conditions that fed into the Black Death killing one-third of the population of Europe.

However confident we are in our comfortable high-tech world keeping us safe, it's always good to remember how tenuous it is -- and the fact that in the long haul, Mother Nature is still very much in charge.

****************************************