Gwynne Dyer: Supervolcanoes, just another thing to worry about

The good thing about volcanoes is that you know where they are. If you don’t want to get hurt, just stay away from them. The bad thing about supervolcanoes is that you may know where they are, but there’s no getting away from them. They only blow up very rarely, but when they do, the whole world is affected. They can cover an entire continent with ash, and lower temperatures sharply worldwide for years.

“This is something that, as a species, we will eventually have to deal with. It will happen in future,” said Dr. Wim Malfait of ETH Zurich (the Swiss Federal institute of Technology), lead author of a recent paper in “Nature Geoscience” that says supervolcano eruptions don’t even need an earthquake as a trigger. “You could compare it to an asteroid impact,” he says. “The risk at any given time is small, but when it happens the consequences will be catastrophic.”

I know you already have enough to worry about, what with climate change and asteroid strikes and the like, but I’m afraid there’s more.

Volcanoes and supervolcanoes both involve magma (molten rock deep underground) that breaks through to the surface, but in practice they are quite different. Volcanoes gradually build themselves into mountains by repeated, relatively modest eruptions of lava. Supervolcanoes are a single massive explosion of magma rising to the surface over a huge area, and blasting at least a thousand cubic kilometres of ash into the atmosphere.

How massive? The largest recent volcanic eruption was Mount Pinatubo in the Philippines, which blew about 10 cubic kilometres of ash and gas into the upper atmosphere in 1991. The result was a 0.4 degree C drop in average global temperature for a year or so. But the eruption of the Yellowstone supervolcano 640,000 years ago was a hundred times as big.

It covered the entire North American continent with ash—and just like an asteroid strike, it threw massive amounts of dust and ash into the stratosphere, where it stayed for years, blocking out much of the sunlight. (It doesn’t rain in the stratosphere, so the debris stays there for a long time.) As a result the average global temperature fell by as much as 10 degrees C for a number of years.

It was temporary, but while it lasted there was a steep fall in the amount of plant material growing on the planet, and a corresponding collapse in animal populations as well. Not mass extinctions, so far as we can tell, and fairly soon the plant and animal species repopulated their former habitats, but it certainly spoiled the party for the equivalent of several human generations.

Homo sapiens were not around 640,000 years ago, but people like us certainly were around when another supervolcano, Toba in northern Sumatra, blew about 73,000 years ago. The event has been tentatively linked with a “bottleneck” in human evolution at that time in which, according to some genetic studies, the human population was squeezed down to only around 1,000 people.

This hypothesis has been challenged by a recent study of the sediments in Lake Malawi by an Oxford University-led team. They did not find any layer in the sediments with much reduced vegetation, which you would expect to see if there was a long-lasting cooling of the climate. This is puzzling, since Toba was the biggest supervolcanic blast in 2.5 million years: it boosted two to three times as much dust and ash into the air as the Yellowstone eruption.

But only a couple of years of severely diminished sunlight would still cause catastrophic population losses in both the plant and the animal kingdoms. Even a relatively short “volcanic winter” would be a huge catastrophe for human beings.

How many people would die if such a catastrophe happened now? It is unlikely that even half of the world’s seven billion people would survive two or three years of severe hunger, and civilization itself would take a terrible beating. Nor is there anything useful you can do to prepare for such a catastrophe, unless you are able to stockpile two or three years’ worth of food for the entire world.

At the moment, our global food reserve will feed the population for only three or four months, so that is not likely to happen. If it does not, then we just have to hope that the calamity doesn’t happen— knowing that we probably will not have much warning if it does.

What Dr. Malfait’s team discovered is that the detonation of a supervolcano is entirely dependent on the temperature of the liquid rock in the underground chamber. As it gets hotter, it gets less dense than the solid rock around it. At this point, it will behave just like an air-filled balloon or football that is held underwater, trying to pop up to the surface.

Eventually, the magma forces its way to the surface over an area of hundreds of square kilometres, expands and explodes. On average, such an explosion only happens once every hundred thousand years, but in practice it could happen at any time, with as little as a few weeks warning. Just thought you’d like to know. Sleep well.

Comments (10) Add New Comment
Steve Newton
Not only that, but Fukushima + volcano = no fun
Rating: 0
Dennis Ryan
If you look around lately, does it seem like "Mother Nature" might be a tad pissed at us for fouling our lovely green space. Supervolcanoes are just, I was going to say, "icing on the cake", but it's more like "hot sauce on the chicken wing".
Rating: -1
Lee L
Yes Gwynne...uh..thanks for that VOLCANIC ALARMISM. The similarity with your aforementioned climate change alarmism and asteroid impact hysteria is telling, right down to the role of the popular media, represented in this case by yourself. In modern science, scare tactics yield funding and apparently subsequent 'peer reviewed' publication which leads to ...uh.. funding.

What point the writing of your article makes eludes me. Perhaps it is a runner up to the announcement of the end of the present interglacial?

Stick to your usual fodder. You are pretty good at that.
Rating: -34
Ummmm... the take home message for me from this article was that there's *nothing* that can be done about an emergent supervolcano (other than live it up in the little time one will have left of course). Hardly a call for increased funding is it?

As for the point of the writing, it's informative and therefore interesting, just like everything else Gwynne Dyer writes.
Rating: +21

Climate change “alarmism”? You are aware that it poses a very real threat, right? There's nothing alarmist about reporting scientific facts. (There is plenty that can be accurately described as alarmist in the hysterical claims of those who would rather you believe it doesn't exist, on the other hand.)
Rating: +16
Pat Crowe
I've always been much more concerned over Earth colliding with another planet.
You can't stash enough corn chips for that scenario let me tell you!
Rating: -4
Ben Sili
Be afraid, be very afraid... and give us your money.
Rating: -12
Lee L

Point is... the media has an unholy role in creating hysteria and this article demonstrates that well. You can gather all this volcanic information easily and BETTER from the US National Parks website or on a little camping trip to Yellowstone. Yes it is surprising, yes it will be bad WHEN it happens but there is d((k all can be done about it which you will realize IF you do the reading

By the way, you may also realize that what you call 'scientific facts' are rife with uncertainty and in the case of climate alarm are far from 'fact' or 'certainty'. Repetition in the media does not make fact or truth.
You can find this out by doing the reading as well. Look up, for example, the history of the IPCC and who is its client organization? It's about politics not science Im afraid.

Rating: -4
Lee L.
I assume you have insurance for the miniscule eventuality that your house might burn down,
Or that you are in favour of maintaining a military, just in case we have to defend ourselves even though there's is very little chance of any major war on the horizon. It is equally important to plan for climate change - and it is happening, here in British Columbia we have 15 million hectares of pine beetle damaged trees - unprecedented and due to the fact that winter temperatures are not cold enough to kill the beetles. And it is not the 'media', pretty much any scientific organization, and the vast majority of the worlds governments agree it is happening.

You can also look back at various societies that have collapsed, often through overuse of resources and we've done enough of that. Yes there's not much we can do about a supervolcano, but consider that the US alone spent $1 trillion on Homeland Security all on the off chance that there might be a terrorist attack somewhere (though most of the incidents that were of any consequence were stopped by citizens -ie. the underwear bomber, shoe bomber, times square bomber etc) I would consider that far more 'alarmist'

Rating: -1
Urban Survivor

If anyone thinks the Yanks spent all that cash to stop "terrorism" then I have a bridge to sell.

The "vast majority" of people thought alot of things that were wrong throughout time (and continue to do so).

Global Wa...OH SORRY, "Climate Change" (chortle) is just another way to separate the folks from their cash.

Check out those "No Pressure" ads on utube for what some of those creeps think of humanity.

Rating: -3
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