Wednesday, May 1, 2013

fire and brimstone, green sky and Black Ocean

Today it is just one week since I returned from Singapore, ran the numbers for the ocean currents which breathe oxygen into the northern oceans of the world, and became quite upset about the problem.

The problem is clearly much worse than I thought before but I (or someone else?) needs to run a few more numbers to get a reasonable sense of how close we may be to fatal consequences, and what the rational response would be. There is of course a weird human instinct to put the head into the sand immediately, and use any one-in-a-thousand hope as an excuse for ignoring the problem altogether.
That places a special burden of responsibility on those few who have some idea of what it means to be rational, to juggle probabilities and uncertainties, and such.

Strictly speaking, my shock from a week ago does not DIRECTLY imply fire and brimstone or even green sky (Peter Ward's apt term for the H2S and radiation which caused the "PT" mass extinction of life about 250 million years ago). It implies black ocean -- a condition where a huge swath of the northern oceans develop a poisonous deep layer, similar to what we see in the Black Sea today.

If you WANT to be calm (ah, a place in the sand where you can bury your head..)...

do think of the Black Sea, a wonderful and beautiful vacation spot for many thousands of people.
I have been there myself, and seen people sunning themselves in bikinis on black gravely sand.
And I have even swum in its waters where they are reasonably deep, next to the craggy cliffs which the Tatar's called something like the "devil's for." Meanwhile, just about 50 meters below, is the greatest reservoir on the earth of a poison (H2S) as powerful as hydrogen cyanide.

People get used to being next to a huge reservoir of poison. People in Pompei got used to living next to a huge volcano. Until one day, it was a bad day, and they all were quickly killed. There are stories
of people in Africa who lived next to a lake which had a similar H2S zone; they were comfortable for centuries, but then a wind blew in a different direction or such, and the next morning there were dead
bodies to clear out for a distance larger than the radius of the lake. I have wondered why the people living next to the Black Sea don't pay a bit more attention to what lies near them; when last I checked, there was a President of Romania who was starting to focus real attention to the threat, but the sivoliki
decided he was too friendly to the EU and was rocking the boat too much, and had him removed and replaced by people restricted to more traditional pathways. I just hope we do not wake up some morning to read headlines of Russia being in a state of extreme anger and violence towards everyone on earth, when a wrong wind blows over Sevastapol in the night and kills all their people in the area.
And I hope we do not end up clearing out dead bodies for a distance equal to the radius of THAT lake,
when the sulfur line reaches the surface! (The barrier between the poison and the normal water has been rising quickly over the past few decades.)

So the well-defined curves of maximum density as a function of salinity, and the prevailing salinity
in the oceans, suggest that the oxygenating currents -- "the lungs of the Northern oceans" -- shut down when the water surface temperature gets to zero degrees C and the ice melts
(about the same time, so far as I can tell.) Current reports, based on actual data, suggest that might be only a decade or two away.  So we may all be "living next to the Black Sea." Black ocean.

That raises three questions: (1) when does the H2S (and methane) come up out of the Black ocean, to start poisoning us?; (2) what is the stream of consequences when it does, to poison in the atmosphere and to the stability of the stratospheric ozone layer (e.g. how soon does death by ultra sunburn occur?);
(3) what could we do to be prepared to change the outcome in case the worst starts to unroll quickly?
(Of course, we could take stronger action to deploy technologies to reduce the global warming, in principle, but certain political forces just wouldn't want to be deprived of their entertainment.)

This morning I located an impressive 300-page study of aerosol dynamics which begins to give me a fix on some aspects of question 2.  Like a lot of the current literature on ocean and atmosphere dynamics, it focuses on empirical data on present conditions, but these are an important clue.

Before that... I was really starting to worry, in my ignorance.  I re-fread Kump's paper on historical H2S emissions on the earth, reminding me of the hard empirical data from biomarkers showing at least 100 ppm (more I think, but maybe 100 ppm in early phases of mass extinction events) of H2S in the atnosphere in the past.  I had the impression, from a few years past, that Black Ocean would essentially push H2S into the atmosphere at a relatively slow rate (due to slow mixing between the huge new reservoir of poison and the atmosphere), such that it would only take a decade or two for the whole earth to smell like the worst cesspool but a thousand years or two to reach direct fatal levels. But what about the killer radiation, due to detsruction of stratospheric ozone? How fast would that be?

I remembered that H2S is a light molecukle, and that light molecules have a tendency to rise.
Because the mass of the stratosphere ozone is about 2 million times less than that of the atmosphere,
and because a molecule of H2S aggressively eats a molecule of ozone, I figured that 1 ppm of H2S at the surface might be enough to eat the whole ozone layer -- and literally fry us. We would get to 1 ppm much sooner than we get to poisonous levels -- so it seemed that this would be the first real killer.

But cheer up -- the aerosol book says that H2S does not even get to the stratosphere now.
Yes, it is a light molecule, but it interacts with OH- in the atmosphere, and with pollution,
so that it is "eaten" itself before it can get to the stratosphere. "Don't worry about the H2S.
It doesn't last long. It just turns into sulfuric acid, and So2 and SO4.) And I remembered what
Peter Ward said about all the sulfuric acid which also rained onto the earth at the time of the PT "green sky" event.

However -- the aerosol report also said that the SO2 and the SO4 themselves also do go up to the stratosphere, and have corrosive effects. Oh, well. We're not really off the hook after all.
Also -- after a certain amount of flux, ratios do change. Light molecules do rise.

By the way, the reason why the poison is rising steadily in the Black Sea ... is due in great part to nutrition, to stuff like agricultural runoff. There is plenty of that all over the Northern hemisphere these days. Zones of anoxia are already a problem, even with the huge influx of oxygen we have today to counter it. And there are the upwelling currents.

In short, it is just a matter of time. How much, we do not know, but I don't see much reason for complacency.

Since ozone depletion is the first plausible source of sudden death, I googled on "geoengineering ozone
hole" and such. Only found one hit, to a well-meaning Afro-American science student.
He proposed lifting up tons of oxygen all the way to the ozone layer, using a neat new superblimp DOD is working on right now. Maybe. But there might be other options, exploiting a bit more chemistry and even physics. It would be nice to know what we could do to save our lives, in case we have to in a hurry, sooner than we think.

Best of luck to us all...


Some further details in response to questions:

(1) Don't the equatorial solar heating and consequent equatorial-polar heat exchange and currents provide enough mixing to avoid such catastrophe?

(2) Don't coriolis currents, perhaps combined with the equatorial currents of (1), do likewise?

There are certainly other sources of current other than the convective currents which send oxygenated cold water down to the depths of the ocean near the poles. However, those other currents are basically pushing in the wrong two dimensions -- latitude and longitude -- and only incidentally to depth. In fact, those other currents have existed for at least a billion years ago or so, but the deep overturning currents powered by the events at the north and south poles are relatively recent -- somewhere between 3 and 22 million years ago.
Before that, he earth generally DID have stratified oceans, resulting in the dozen or so episodes of mass extinctions described in Ward's book. The coriolis effects and such were not enough to stop that. In fact, from Kump's account, they helped to make things MORE precarious, because while they did not prevent anoxia in the deep ocean, they did mix H2S up into the atmosphere. Powerful enough to cause enough upwelling (localized UPWARDS motion, not the downwards energy of convection) to slowly leak enough H2S to destroy the ozone layer and poison the earth.

 (3) Mightn't underwater topography in conjunction with the currents of (1) and (2) provide additional upwellings and mixings sufficient to do likewise?

And (4), and most intriguingly, if I understand correctly, the Earth had a single land-mass at the time of the PT junction, the supercontinent called Pangaea: Could that single-continent conformation have played a role, and perhaps the critical one, in the PT extinction?


Ward's book describes about a dozen mass extinctions. As I recall, the most recent was long after Pangaea broke up.
There was and is upwelling, in addition to the big downwards-convective oxygenating currents we have today ,
but they only made things worse.


1 comment:

  1. The 1 February 2013 issue of Science has a couple of papers (p.563 and p.568) on the changes in the Southern Ocean due to the opening of the Ozone hole there due to CFCs.

    The research that you have done sounds like pretty serious consequences could be right around the corner. Would you consider writing a review paper that presents this material and submitting it to Science or Nature. It's fine to read about this in your blog, but perhaps it should be seen by a wider audience.

    Allen Taylor