The mysteries of the deep

I've heard it said that we know more about the surface of the Moon than we do about the deep oceans on the Earth.

I've never seriously attempted to find out how accurate this is (and honestly, don't know how you'd compare the two), but I suspect it's substantially correct.  About seventy percent of the Earth's surface is covered by water, and given the difficulty of seeing what's down there -- even by remote telemetry -- it's no wonder we're still finding things in the ocean we never knew existed.

Take, for example, the study that appeared in Current Biology last week about the Clarion-Clipperton Zone.  The CCZ is the region between the Clarion Fracture Zone and the Clipperton Fracture Zone in the central Pacific, with an area of about six million square kilometers.  It contains several (apparently dormant or extinct) volcanoes, a number of submarine troughs of uncertain seismic activity, and a rough, mountainous topography.

[Image is in the Public Domain courtesy of the United States Geological Survey and the Department of the Interior]

The prevailing wisdom has been that most of the open ocean has relatively low biodiversity.  To put it more simply, that there just ain't much out there.  If you're in the middle of the ocean, any given cubic meter of water is unlikely to have many living things in it beyond single-celled plankton.  And -- supposedly -- the floor of the deep ocean, with crushing pressures, no light, and constant temperatures just above the freezing point of water, is often pictured as being pretty much devoid of life except for the bizarre hydrothermal vent communities.

That concept of the deep oceans needs some serious re-evaluation.  Last week's paper featured a survey of the abyssal life in the Clarion-Clipperton Zone, and found nearly six thousand species of animals...

...of which 92% were unknown to science.

The coolness factor of this research is tempered a little by the reason it was conducted.  The CCZ is being studied because of its potential for deep-sea mining.  The seafloor there has a rich concentration of manganese nodules, concretions of metal oxides and hydroxides (predominantly manganese and iron, with lower concentrations of other heavy metals), which are of immense value to industry.  Add to that the fact that the CCZ is in international waters -- so, basically, there for whoever gets there first -- and you have a situation that is ripe for exploitation.

What makes this even more complex is that the metals in the nodules are used, amongst other things, for high-efficiency electronics, including renewable energy systems.  The cost, though, might be the destruction of an ecosystem that we've only begun to study.

"There are some just remarkable species down there," said Muriel Rabone, of the Natural History Museum of London, who co-authored the study.  "Some of the sponges look like classic bath sponges, and some look like vases.  They’re just beautiful.  One of my favorites is the glass sponges. They have these little spines, and under the microscope, they look like tiny chandeliers or little sculptures.  There are so many wonderful species in the CCZ, and with the possibility of mining looming, it’s doubly important that we know more about these really understudied habitats."

So much of what humans have done seems to be blundering around blindly and only afterward seeing what the consequences are.  Perhaps we should investigate the ocean's mysteries before we attempt to use it for profit.

It seems fitting to end with a quote from H. P. Lovecraft, whose fascination with the ocean returns time and time again in his fiction: "But more wonderful than the lore of old men and the lore of books is the secret lore of ocean.  Blue, green, grey, white, or black; smooth, ruffled, or mountainous; that ocean is not silent.  All my days have I watched it and listened to it, and I know it well.  At first it told to me only the plain little tales of calm beaches and near ports, but with the years it grew more friendly and spoke of other things; of things more strange and more distant in space and in time.  Sometimes at twilight the grey vapours of the horizon have parted to grant me glimpses of the ways beyond; and sometimes at night the deep waters of the sea have grown clear and phosphorescent, to grant me glimpses of the ways beneath.  And these glimpses have been as often of the ways that were and the ways that might be, as of the ways that are; for ocean is more ancient than the mountains, and freighted with the memories and the dreams of Time."

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Reconsidering Storegga

Ever heard of the Storegga Slide?

It sounds like some bizarre crossover between Scandinavian folk music and a country line dance, but it isn't.  It's an event that took place 8,150 years ago (plus or minus thirty years or so) and is entirely unlike anything we've seen since.

The simplest description is that it was an underwater landslide.  But this thing was bigger than any landslide you've ever heard of.  It took place in the North Atlantic between Iceland and Norway.  For uncertain reasons -- but probably linked to seismic activity along the Mid-Atlantic Ridge -- a 290-kilometer-long piece of continental shelf collapsed, sending an estimated 3,500 cubic kilometers of debris sliding down the continental slope, where it ultimately piled up on the floor of the deep ocean.

What happened next is kind of mind-blowing, but to get how it worked, we have to take a brief digression into biochemistry.

It's thought that the most numerous organisms on Earth are methanogens, a group of bacteria that are kind of everywhere in anaerobic mud (including the sediments of the oceanic abyss).  As you might guess from the name, these bacteria produce methane as a waste product of their metabolism.  If they're living at the bottom of a shallow lake, the methane is in gaseous form and bubbles up when the mud is disturbed, giving it the name "marsh gas." 

But something more interesting happens in the deep ocean.  At the enormous pressures and low temperatures found in the abyss, the methane forms a weird substance called methane clathrate (also known as frozen methane hydrate).  It's a crystalline slush made of a latticework of water and methane.  If you bring it up to the surface -- which, as you'll see, has to be done carefully -- it looks like snow.

But it's flammable.

[Image of methane clathrate is in the Public Domain, courtesy of the United States Geological Service]

So back to the Storegga Slide, wherein an enormous clump of debris went tumbling down the continental slope... and landed in the clathrate-rich mud of the abyssal plain.

Methane clathrate isn't just flammable; it's unstable.  If anything wallops it hard enough, it breaks up the lattice, and the two compounds separate.  The methane turns back into a gas, the water to a liquid. 

Some of you probably have gone scuba diving, and noticed what happens to the air bubbles when you breathe out.  The bubbles rise (duh) but more interestingly, they expand.  The higher you go in the water column, the lower the pressure, and the more the air in the bubble is free to balloon outward.

A lot.  One liter of methane clathrate produces 169 liters of methane gas (at zero degrees Celsius and one atmosphere of pressure).  So when the Storegga Slide crashed into the methane clathrate on the ocean floor, it caused an unknown (but huge) quantity of methane clathrate to fall apart, making it suddenly increase in volume by a factor of 169 -- triggering an explosion that displaced enough water to generate a megatsunami.

This comes up because of a paper last week in the journal Boreas that looked at the effect of the Storegga Slide on nearby land, and found that the tsunami this generated was on the order of thirty meters high.  For comparison purposes, the devastating tsunami generated by the 2011 Japanese earthquake maxed out at a little under ten meters.

The Storegga Slide tsunami was three times higher than that.  It completely inundated what is now northern Scotland.  It's also likely this is what destroyed Doggerland, a broad, marshy land that once connected Great Britain to northern continental Europe.  Doggerland was already in trouble -- at this point, the climate was warming and the seas were rising -- but the Storegga Slide tsunami would have been catastrophic.  Unlike the rugged terrain of Scotland, Doggerland was a featureless flat plain, and the tsunami rolled across it like a bulldozer.  This severed Great Britain from the rest of Europe -- isolating the Mesolithic people there permanently.

[Image licensed under the Creative Commons Francis Lima, Doggerland3er en, CC BY-SA 4.0]

All this isn't speculation, by the way.  The fact that Doggerland was once dry land (well, dry-ish) was established when a trawler out in the North Sea east of the Wash brought up a barbed antler point that was dated to about ten thousand years ago.  Since that time, lots of other artifacts have been discovered out there on the ocean floor, including prehistoric tools and the bones of mammoths, lions, and other extinct fauna.

And of course, what this makes me think about is how much more methane clathrate there is out there.  "Methane burps" like this one -- although the word "burp" kind of underplays how enormous these are -- release enough methane into the atmosphere to raise the temperature significantly.  In fact, a massive methane clathrate release is thought to be the cause of the Paleocene-Eocene Thermal Maximum of 55 million years ago, during which the average temperature climbed by between five and eight degrees Celsius, causing widespread extinction and ecosystem disruption.  That "methane burp" at the PETM is thought to have been a hundred times bigger than the Storegga Event.

Ready for the punchline?  The estimates are that the rate we're pumping carbon into the atmosphere from fossil fuel burning is right around the same as the rate that led to the PETM.

So by all means, governmental leaders, continue to ignore the scientists who have been warning you about this for decades.  Business as usual, damn the torpedoes, full speed ahead.

The universe is a dangerous place.  The Storegga Slide and the resultant tsunami happened suddenly and without warning.  Much more commonly, earthquakes and volcanoes can cause tremendous loss of life and property.

But it's a little terrifying to see that what we're doing to our home right now is equivalent to some of the most violent ecological shifts in the geologic record.

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I'm in awe of people who are true masters of their craft.  My son is a professional glassblower, making precision scientific equipment, and watching him do what he does has always seemed to me to be a little like watching a magic show.  On a (much) lower level of skill, I'm an amateur potter, and have a great time exploring different kinds of clays, pigments, stains, and glazes used in making functional pottery.

What amazes me, though, is that crafts like these aren't new.  Glassblowing, pottery-making, blacksmithing, and other such endeavors date back to long before we knew anything about the underlying chemistry and physics; the techniques were developed by a long history of trial and error.

This is the subject of Anna Ploszajski's new book Handmade: A Scientist's Search for Meaning Through Making, in which she visits some of the finest craftspeople in the world -- and looks at what each is doing through the lenses of history and science.  It's a fascinating inquiry into the drive to create, and how we've learned to manipulate the materials around us into tools, technology, and fine art.

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Halting the conveyor

The Irish science historian James Burke, best known for his series Connections and The Day the Universe Changed, did a less-well-known two-part documentary in 1991 called After the Warming which -- like all of his productions -- approached the issue at hand from a novel angle.

The subject was anthropogenic climate change, something that back then was hardly the everyday topic of discussion it is now.  Burke has a bit of a theatrical bent, and in After the Warming he takes the point of view of a scientist in the year 2050, looking back to see how humanity ended up where they were by the mid-21st century.

Watching this documentary now, I have to keep reminding myself that everything he says happened after 1991 was a prediction, not a recounting of actual history.  Some of his scenarios were downright prescient, more than one of them down to the year they occurred.  The Iraq War, the catastrophic Atlantic hurricane barrage in 2005, droughts and heat waves in India, East Africa, and Australia -- and the repeated failure of the United States to believe the damn scientists and get on board with addressing the issue.  He was spot-on that the last thing the climatologists themselves would be able to figure out was the effect of climate change on the deep ocean.  He had a few misses -- the drought he predicted for the North American Midwest never happened, nor did the violent repulsion of refugees from Southeast Asia by Australia.  But his batting average still is pretty remarkable.

One feature of climate science he went into detail about, that beforehand was not something your average layperson would probably have known, was the Atlantic Conveyor -- known to scientists as AMOC, the Atlantic Meridional Overturning Circulation.  The Atlantic Conveyor works more or less as follows:

The Gulf Stream, a huge surface current of warm water moving northward along the east coast of North America, evaporates as it moves, and that evaporation does two things; it cools the water, and makes it more saline.  Both have the effect of increasing its density, and just south of Iceland, it reaches the point that it becomes dense enough to sink.  This sinking mechanism is what keeps the Gulf Stream moving, drawing up more warm water from the south, and that northward transport of heat energy is why eastern Canada, western Europe, and Iceland itself are as temperate as they are.  (Consider, for example, that Oslo, Norway and Okhotsk, Siberia are at the same latitude -- 60 degrees North.)

[Image is in the Public Domain courtesy of NASA/Goddard Space Flight Center]

Just about any high school kid, though, has heard about the Gulf Stream, usually in the context of the paths of sailing ships during the European Age of Exploration.  What many people don't know, however, is that if things warm up, leading to the melting of the Greenland Ice Sheets, it will cause a drastic drop in salinity at the north end of the Gulf Stream, making that blob of water too fresh to sink.

The result: the entire Atlantic Conveyor stops in its tracks.  No more transport of heat energy northward, putting eastern Canada and northwestern Europe into the deep freeze.  The heat doesn't just go away, though -- that would break the First Law of Thermodynamics, which is strictly forbidden in most jurisdictions -- it would just cause the south Atlantic to heat up more, boosting temperatures in the southeastern United States and northern South America, and fueling hurricanes the likes of which we've never seen before.

Back in 1991, this was all speculative, based on geological records from the last time something like that happened, on the order of thirteen thousand years ago.  The possibility was far from common knowledge; in fact, I think After the Warming was the first place I ever heard about it.

Well, score yet another one for James Burke.

A paper this week in Proceedings of the National Academy of Science describes research by Johannes Lohmann and Peter Ditlevsen of the University of Copenhagen indicating the that based on current freshwater output from the melting of Arctic ice sheets, that tipping point from "saline-enough-to-sink" to "not" might be too near to do anything about.  "These tipping points have been shown previously in climate models, where meltwater is very slowly introduced into the ocean," Lohmann said, in an interview with Gizmodo.  "In reality, increases in meltwater from Greenland are accelerating and cannot be considered slow."

The authors write -- and despite the usual careful word choice for scientific accuracy's sake, you can't help picking up the urgency behind the words:

Central elements of the climate system are at risk for crossing critical thresholds (so-called tipping points) due to future greenhouse gas emissions, leading to an abrupt transition to a qualitatively different climate with potentially catastrophic consequences...  Using a global ocean model subject to freshwater forcing, we show that a collapse of the Atlantic Meridional Overturning Circulation can indeed be induced even by small-amplitude changes in the forcing, if the rate of change is fast enough.  Identifying the location of critical thresholds in climate subsystems by slowly changing system parameters has been a core focus in assessing risks of abrupt climate change...  The results show that the safe operating space of elements of the Earth system with respect to future emissions might be smaller than previously thought.

The Lohmann and Ditlevsen paper is hardly the first to sound the alarm.  Five years ago, a paper in Nature described a drop in temperature in the north Atlantic that is precisely what Burke warned about.  In that paper, written by a team led by Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research, the authors write, "Using a multi-proxy temperature reconstruction for the AMOC index suggests that the AMOC weakness after 1975 is an unprecedented event in the past millennium (p > 0.99).  Further melting of Greenland in the coming decades could contribute to further weakening of the AMOC."

Once again, the sense of dismay is obvious despite being couched in deliberately cautious science-speak.

Even if the current administration in the United States explicitly says that addressing climate change is one of their top priorities, they're facing an uphill battle.  Baffling though it is to me, we are still engaged in fighting with people who don't even believe climate change exists, who understand science so little they're still at the "it was cold today, so climate change isn't happening" level of understanding.  (To quote Stephen Colbert, "And in other good news, I just ate dinner, so there's no such thing as world hunger.")  Besides outright stupidity (and apparent inability to read and comprehend scientific research), there's the added problem of elected officials being in the pockets of the fossil fuel industry, the money from which gives them a significant incentive for keeping the voting public ignorant about the issues.

Until we hit the tipping point Lohmann and Ditlevsen warn about.  At which point the effects will be obvious.

In other words, until it's too late.

If the Atlantic Conveyor shuts down, the results will no longer be arguable even by climate-change-denying knuckle-draggers like James "Senator Snowball" Inhofe.  The saddest part is that we were warned about this thirty years ago by a science historian in terms a layperson could easily understand, and -- in Burke's own words -- we sat on our hands.

And as with Cassandra, the character from Greek mythology who was blessed with the gift of foresight but cursed to have no one believe what she says, we'll only say, "Okay, I guess Burke and the rest were right all along" as the world's climate systems are collapsing around us.

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 Many of us were riveted to the screen last week watching the successful landing of the Mars Rover Perseverance, and it brought to mind the potential for sending a human team to investigate the Red Planet.  The obstacles to overcome are huge; the four-odd-year voyage there and back, requiring a means for producing food, and purifying air and water, that has to be damn near failsafe.

Consider what befell the unfortunate astronaut Mark Watney in the book and movie The Martian, and you'll get an idea of what the crew could face.

Physicist and writer Kate Greene was among a group of people who agreed to participate in a simulation of the experience, not of getting to Mars but of being there.  In a geodesic dome on the slopes of Mauna Loa in Hawaii, Greene and her crewmates stayed for four months in isolation -- dealing with all the problems Martian visitors would run into, not only the aforementioned problems with food, water, and air, but the isolation.  (Let's just say that over that time she got to know the other people in the simulation really well.)

In Once Upon a Time I Lived on Mars: Space, Exploration, and Life on Earth, Greene recounts her experience in the simulation, and tells us what the first manned mission to Mars might really be like.  It makes for wonderful reading -- especially for people like me, who are just fine staying here in comfort on Earth, but are really curious about the experience of living on another world.

If you're an astronomy buff, or just like a great book about someone's real and extraordinary experiences, pick up a copy of Once Upon a Time I Lived on Mars.  You won't regret it.

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