It seems there’s really no complete measurements on how much CO2 is coming out of volcanoes, both active and inactive.
In 1992, it was thought that volcanic degassing released something like 100 million tons of CO2 each year. Around the turn of the millennium, this figure was getting closer to 200. The most recent estimate, released this February, comes from a team led by Mike Burton, of the Italian National Institute of Geophysics and Volcanology – and it’s just shy of 600 million tons. It caps a staggering trend: A six-fold increase in just two decades.
These inflating figures, I hasten to add, don’t mean that our planet is suddenly venting more CO2.
Humanity certainly is; but any changes to the volcanic background level would occur over generations, not years. The rise we’re seeing now, therefore, must have been there all along: As scientific progress is widening our perspective, the daunting outline of how little we really know about volcanoes is beginning to loom large.
The exhalations of our planet can be spectacularly obvious. The fireworks, though, are only part of the picture. We now know that the CO2 released during volcanic eruptions is almost insignificant compared with what happens after the camera crews get bored. The emissions that really matter are concealed. The silent, silvery plumes which are currently winding their way skyward above the 150 or so active volcanoes on our planet also carry with them the bulk of its carbon dioxide. Their coughing fits might catch the eye — but in between tantrums, the steady breathing of volcanoes quietly sheds upwards of a quarter of a billion tons of CO2 every year.
We think. Scientists’ best estimates, however, are based on an assumption. It might surprise you to learn that, well into the new century, of the 150 smokers I mentioned, almost 80 percent are still as mysterious, in terms of the quantity of CO2 they emit, as they were a generation ago: We’ve only actually measured 33.
If the 117 unsampled peaks follow a similar trend, then the research community’s current projection might stand. But looking through such a small window, there’s no way of knowing if what we have seen until now is typical or not. It’s like shining a light on a darkened globe: randomly, you might hit Australia, and think you’d seen it all – while on the edge of your beam, unnoticed, would be Asia. Our planet’s isolated volcanic frontiers could easily be hiding a monster or two; and with a bit of exploration, our estimate of volcanic CO2 output could rise even higher.
You’d think that would be enough. That might be my fault — I tend to save the weird stuff until the end. Recently, an enigmatic source of volcanic carbon has come to light that isn’t involved with lava — or even craters. It now seems that not only is there CO2 we can’t get to, there’s some we can’t even see.
Even more incredibly, it even seems that some volcanoes which are considered inactive, in terms of their potential to ooze new land, can still make some serious additions to the atmosphere through diffuse CO2 release. Residual magma beneath dormant craters, though it might never reach the surface, can still ‘erupt’ gases from a distance. Amazingly, from what little scientists have measured, it looks like this process might give off as much as half the CO2 put out by fully active volcanoes.
If these additional ‘carbon-active’ volcanoes are included, the number of degassing peaks skyrockets to more than 500. Of which we’ve measured a grand total of nine percent. You can probably fill it in by now — we need to climb more mountains.
- Long Invisible, Research Shows Volcanic CO2 Levels Are Staggering (Op-Ed) (livescience.com)
- Indonesia’s Mount Sinabung continues to erupt (abc.net.au)
- Volcano spews ash 3km high (stuff.co.nz)