I had never heard of this, though it happened in my lifetime. Perhaps the news cycle was all about the reactor explosion and fire in a place that is often called “Chernobyl”, which happened earlier that year.
From [wik]
On 21 August 1986, a limnic eruption at Lake Nyos in northwestern Cameroon killed 1,746 people and 3,500 livestock.[1]
The eruption triggered the sudden release of about 100,000–300,000 tons (1.6 million tons, according to some sources) of carbon dioxide (CO2). The gas cloud initially rose at nearly 100 kilometres per hour (62 mph; 28 m/s) and then, being heavier than air, descended onto nearby villages, displacing all the air and suffocating people and livestock within 25 kilometres (16 mi) of the lake.
A degassing system has since been installed at the lake, with the aim of reducing the concentration of CO2 in the waters and therefore the risk of further eruptions.
I remember reading about massive CO2 gas clouds, caused by burn-off methane, being a thing in the Permian.
If I understand correctly we aren’t going to have to worry about that, exactly, because humans are busy extracting and burning all those bubbles of gas, already. The CO2 clouds may be a result of other processes, like algae blooms, or stagnant water.
The one thing that sticks in my mind is “16 miles is a hell of a long way to run” especially when you’re out of breath. I imagine that the typical human reaction to something like this would be incomprehension until it was too late to do anything else.
You can’t even drive your way out of it with an internal combustion engine. (Cue the Elon Skum fanboys using this to argue for electric cars….)
This also happened at Lake Monoun [wik]
Intransitive@#1:
Cue the Elon Skum fanboys using this to argue for electric cars….
“Sh… charging… aaaaagggghhhhhh…”
I distinctly recall reading a National Geographic* article on that lake around that time. Scary stuff all right.
* That was of course back when NatGeo had real geography articles and before it became National Jesus News…
Assuming the gas layer is too thick to practicably get above, and you have failed to lay in a sufficient supply of air or oxygen to allow you to flee , an electric vehicle would be mighty handy, or the cloud to dissipate (Fortuitous wind?) you would be well and truly fucked.
Of course the issue would likely be mute simply because CO2 is colorless and has no distinctive odor. A cloud inundating a town would give no clue except people losing consciousness.
Way back in the day there was far less of an established and enforced protocol for entry into confined spaces. I was working as a longshoreman and a crew on an adjacent dock lost three people. Removing everything from a ship that was being decommissioned they had to clear a storeroom that hadn’t been opened in years. The crew chief went down to figure out what he was up against and wasn’t seen for some time. They went looking for him and heard he was checking out a storeroom. They figured he had fallen and hurt himself so one of the guys went down … and wasn’t heard from for some time. A third guy went down … and wasn’t heard from. With three missing they got serious. They would have lost another but looking down they saw one of the original three laying under the ladder. Evidently there was no warning or time to react. They climbed down into an essentially oxygen-free atmosphere and lost consciousness before realizing anything was wrong. Quick and quiet.
A year later there was a massive campaign to train people to deal with the hazards of confined spaces. Ours was just one of a long list of incidents. Everyone got an eight-hour training. Every crew chief went through a three day program and crews got test instruments and specialized equipment.
I’ve wondered about what effect a mass death scene might have on people without a materialistic or scientific POV. You walk into a town and everyone and everything is dead. No struggle, no blood. People and animals by the score just fell over dead. Spooky. Lacking any other explanation resort to supernatural explanation seems likely.
With CO2, there may not be an odor per se, but you’d know, as it burns. A lungful will knock you down pretty much instantly.
Plants would survive, presumably. But I’d assume any mammal or bird with a high metabolism would die. It would be uncannily quiet.
@ lorn: “CO2 is colorless and has no distinctive odor. A cloud inundating a town would give no clue except people losing consciousness.”
I take issue with that, as would anybody who’s been exposed to even mild increases in CO2 in their breathing mix.
Elevated CO2 is horrible. It’s presence in one’s bloodstream is the primary driver in the urge to breathe (raised acidity) and getting what divers call a CO2 hit is really horrible and leads to, if you’re lucky, *near* uncontrolable panic. Even before it gets to that level, a splitting headache is a very common manifestation, even if just breathing rapidly on SCUBA.
I’m afraid those citizens would have had a few moments of blind panic before passing out.
Glad I wasn’t there.
Proximity to volcanos is a feature of limnic lakes. You would definitely notice the stench of sulfur.
Wiki
The Black Sea is the largest meromictic body of water. It is anoxic below 1000 m. There is some evidence that massive landslides may have triggered similar releases of toxic gas clouds in antiquity, though I can’t remember which historian wrote of entire Greek communities being wiped out by noxious vapors.
As I remember it, lake Nyos burped in the middle of the night so after everybody went to sleep they didn’t wake up and the animals were all penned.
I have experienced what it’s like to breathe CO2 when I was a test subject about 40 years ago in our exercise physiology lab when we used the ‘modified Fick CO2 rebreathing method’ to find cardiac output. [Totally non-invasive, you just have to breathe 100% CO2 for a couple of breaths then cardiac output is calculated from the slope of the breath-by-breath change in expired CO2 afterwards – IIRC]. This was done at rest and during moderate intensity exercise on a bike ergometer. It was no problem at rest, but I had to be held up because I was blacking out momentarily at the end of the exercise test.
Inert atmospheres still kill people pretty regularly. A “good” example was some guys who went into a carbon steel tank that had been filled with water, for years. They drained the tank and opened the manway and went in, because obviously there’d be nothing toxic in there because hey, water, right? Except… the interior of the tank hadn’t ever been exposed to air. And when it was, it reacted with all that oxygen and rusted, pretty rapidly. And so the oxygen was depleted… and people died. And people who tried to rescue those people died.
I’ve always been curious why the notoriously barbaric countries that execute people use expensive, complex and theatrical methods with potential to go wrong or even not be available due to suppliers of lethal drugs
having an attack of consciencenot wanting to be associated with such barbarity because it hits the bottom line, rather than simply putting the victim in an oxygen deficient atmosphere for thirty minutes or so. Simple, reliable, cheap, and according to the few people who’ve made it back from passing out from it without suffering actual brain damage, pretty painless. Oh… that’s the reason they don’t do it – barbarians, sorry, as you were.I remember reading “Cameroon with Egbert” by noted modern bicyce explorer Dervla Murphy who described her travel through the Lake Nyos restricted zone. Fascinating and spooky.
I don’t remember the specific lake, but I remember reading about that phenomenon when I was younger. Kinda scary concept.
I’ve heard similar about urban explorers getting into abandoned ballistic missile silos, because there is so much iron/steel, that all of the atmospheric oxygen has been depleted rusting it over the years, and there is effectively no air circulation in those things…
On a darker note, I’ve heard that those little “party” disposable cannisters of helium for balloons now are 80% He, 20% O2, so that people can’t use them for “exit bags”…
If you want to give yourself a proper dose of the willies you should take a look Lake Kivu in the DRC/Rwanda – about 2000 times bigger than Nyos, and it overturns every millennia or so. Goma (pop. 700k) is on the northern shore, sandwiched between the lake and Nyirangogo.
An interesting city, that.
One up for the people living in sealed environments with recycled air, I guess. We should probably get on that actually, before the atmosphere does become lethal…
n.b. I’m pretty sure plants breathe much the same as we do, just slower. I imagine it takes longer to suffocate a tree and the cloud had dispersed before then.