As of the time of writing, if you do a news search for Yellowstone Volcano, it’s dominated by headlines like “Yellowstone volcano: ‘Greatest catastrophe ever’” and “Yellowstone eruption ‘worst-case scenario’ exposed by USGS Chief.”
We’re all going to die.
Here’s the good news…that full page of horrible Yellowstone headlines are all from the same paper, the Daily Express. A British tabloid. For reasons I haven’t ever worked out, British tabloids love to predict Death By Supereruption.
So, what are the actual chances of Yellowstone erupting, and if it does, will it end the world?
Yellowstone has, indeed, caused chaos in the past. The Yellowstone hotspot track has been associated with more than one of these. The largest was 8.7 million years ago, and was called the Grey’s Landing supereruption. The most recent major eruption was 630,000 years ago. This has caused some people to argue that we’re somehow “overdue” for one.
Volcanos Don’t Have a Regular Pattern
Unlike Old Faithful (who really isn’t anymore as the hotspot drifts), volcanos don’t erupt on any kind of a schedule.
There’s no such thing as “overdue” for an eruption, and even if there was, the current recurrence rate of Yellowstone has now been recalculated…to about once every 1.5 million years (before it was once in 500,000, and that was the case in the past, but the hotspot is apparently weakening).
Which means we’re not overdue, if there was such a thing, for another 900,000 years. That’s more than three times the entire lifespan of our species so far.
Of course, that doesn’t mean it’s impossible that Yellowstone will produce a supereruption tomorrow, but the calculated odds are 1 in 700,000.
Even if it Does Blow it Won’t Kill All of Us
Then, of course, there’s the idea that a supereruption will be an extinction event that wipes out humanity.
Back to the Grey’s Landing super-eruption. This is the worst thing Yellowstone has ever done.
So, what did it do?
It buried and sterilized an area the size of New Jersey. It also released a lot of particulates into the atmosphere. Given how long ago it was, we don’t know what impact those had, but we do know what impact other eruptions have had.
First of all, the ash released by the volcano doesn’t stay in the air very long. It comes down. In 2010, Eylafjallajökull erupted in Iceland. It threw up enough ash to render air travel unsafe in Europe for six days. A larger eruption might affect a larger area, but not for as long.
Second of all, volcanic eruptions tend to result in global cooling. This is partially balanced by CO2 release (which of course causes warming). In 1991, Pinatubo erupted, releasing a 20-million ton sulfur dioxide cloud into the stratosphere. The entire Earth cooled by about 1.3 degrees F for…three years.
So, we can extrapolate that Grey’s Landing probably cooled the planet by a few degrees for a few years. Enough to potentially cause the extinction of some marginal species (and very bad for anything endemic to the immediate area), but certainly not a mass extinction event.
From that, we can predict the likely effect of a supereruption.
First of all, it would cause a significant mass casualty event and render a good part of the western US uninhabitable for a significant amount of time. This would, needless to say, be pretty terrible for the global economy.
Second, it would deposit ash over much of the continent. This would cause issues for people and animals, and we’d all be wearing masks again for a little while. The ash would settle quickly, and need to be cleaned out of our cities and homes. It might also affect the power grid by choking equipment. It would affect soil chemistry and thus potentially cause short-term crop failures; however, when properly mixed, volcanic ash has been shown to be beneficial to soil quality in the medium term.
Third, it would result in several years of noticeable global cooling. This could also cause food shortages across the globe, although it might give us a bit of a hand dealing with global warming.
What it would not do is destroy our species or civilization. It would totally suck, like…oh, well, like a global pandemic totally sucks. But it wouldn’t be an extinction event.
What About Smaller Eruptions at Yellowstone?
Those happen all the time! Yellowstone is still a highly geologically active area.
The most common kind of eruption in the park is called a hydrothermal explosion, and we get one every few years. Think of this as a geyser throwing a tantrum. Rocks get thrown in the air and a small crater forms. Most of these explosions are very small, although they have been known to cause craters over a kilometer wide.
The more typical small ones would only be a hazard to extremely unlucky park visitors and rangers. They happen more often in the winter and the evening, when fewer people are around. You would have to be close to one, in which case there’s a risk of rocks falling on your head or of a release of toxic gas. (Note that the reason they keep geysers fenced off is because they do occasionally burp rocks).
A larger one could end up killing people, but they’re not that common.
The second most likely scenario is a simple lava flow. The most recent lava flow eruption at Yellowstone took place 70,000 years ago. Past lava flows at Yellowstone have been slow moving; an eruption would damage infrastructure in the park but would be easy enough to avoid. We would likely get enough warning to tell people to get out of the area. Anyone who got killed would probably be somebody trying to get pictures, because humans. Once the lava dried we would be able to…
…use it as a new tourist attraction.
Are There Other Supervolcanos?
Yellowstone may, in fact, never give us another supereruption. Phewf. But what about other supervolcanoes?
The most recent supervolcano eruption was Taupo, in New Zealand, which erupted 26,500 years ago…recently enough that there’s likely something in oral history about it if we dug. (Which should make you relieved; it didn’t kill everyone then, after all).
There are 20 known supervolcanoes on Earth, including those two, but only six are considered active and likely to present a risk. The other five are the Long Valley Caldera in east-central California, just south of Mono Lake; the Valles Caldera in New Mexico, Lake Toba in North Sumatra, the Taupo Caldera in New Zealand and Aira Caldera in southern Japan. None of them seem to be about to go off, though.
And, of course, new supervolcano sites might be created in the future. We live on a dynamic planet.
For right now, though, it’s worth remembering three things:
- Supervolcanoes are rare.
- They wouldn’t destroy life on this planet or even our entire civilization.
- We’ll probably see them coming and be able to at least evacuate people.
Yellowstone is not about to erupt and kill us all, even if after weeks of quarantine some of us might almost welcome it.