Supervolcanic eruptions are approximately 10 times as powerful as the eruption that caused the year without a summer in 1816. A supervolcanic eruption would cause local devastation, but the main problem is blocking the sun for years and starvation (with possible loss of civilization without recovery and other far future effects). Indeed, many people think that the genetic bottleneck of humans going to a population of only a few thousand was due to a super volcanic eruption 74,000 years ago. It is widely assumed that there is nothing we can do to prevent or mollify supervolcanic eruptions. However, I came up with over 50 possible interventions. In the paper, we could not get into economics. I have done some initial estimates that indicate that the most promising interventions of adding soil or water on top of the supervolcano to delay an eruption for 100 years would likely be cost-effective only considering the present generation. However, this is in isolation. In reality, the first thing we should do is get prepared with alternate foods that are not dependent on sunlight. This would protect against the majority of the damage associated with a supervolcanic eruption, making prevention of a supervolcanic eruption less cost-effective. Still, since people are already doing research on supervolcanic eruptions, it may make sense to nudge that research towards directions that would reduce global catastrophic/extistential risk.
Here is the full paper and below is the abstract:
A supervolcanic eruption of 10^15 kg could block the sun for years, causing mass starvation or even extinction of some species, including humans. Despite awareness of this problem for several decades, only five interventions have been proposed. In this paper, we increase the number of total possible interventions by more than an order of magnitude. The 64 total interventions involve changing magma characteristics, venting magma, strengthening the cap (rock above the magma), putting more pressure on the magma, stopping an eruption in progress, containing the erupted material, disrupting the plume, or provoking a less intense eruption. We provide qualitative evaluations of the feasibility and risk of 38 of the more promising interventions. The two most promising interventions involve putting more pressure on the magma and delaying the eruption with water dams or soil over the magma chamber. We perform a technical analysis, accurate to within an order of magnitude, and find that water dams and soil and could statistically delay the eruption for a century with 1 and 15 years of effort, respectively. All actions require essentially untested geoengineering challenges along with economic, political and general public acceptance. Further work is required to refine the science, provide cost estimates, and compare cost effectiveness with interventions focusing on adapting to a supereruption.
Your food resilience work is great: fascinating and really important! Indeed, I first heard of your supervolcano paper via your interview with Rob Wiblin which was primarily about feeding humanity after a catastrophe. In the grand scheme of things, that's rightly higher priority, but the supervolcano stuff also caught my interest.
I happen to know a couple of volcanologists, so I asked them about your paper. They weren't familiar with it, but independently stressed that something quite tractable that would benefit from more resources is better monitoring of volcanoes and prediction of eruptions.
The typical application of forecasting eruptions is evacuation. But that's sociologically tricky when you inevitably have probabilities far from 1 and uncertain timelines, since an evacuation that ends up appearing unnecessary will lead to low compliance later (the volcanologists "cried wolf"). With interventions to prevent an eruption, that's much less of an issue. Say you had a forecast that a certain supervolcano has a probability of 20% of erupting in the next century, so many orders of magnitude above base rate. That's still realistically pretty useless from the point of view of evacuation, but would make your kind of interventions very attractive (if they work in that case).
So if it could shown that these interventions are likely tractable even when a potential near term eruption has been detected, then that would justify increased investment both in detection/forecasting and developing these approaches.