If Yellowstone erupts…

Summer Wyatt-Buchan assesses the possibility of a super-volcano eruption and analyses the catastrophic impacts it would have on humanity.

Yellowstone National Park Original artwork courtesy of Yana Marchuk

Located in the Western US, Yellowstone National Park spreads through the states of Wyoming, Montana and Idaho, stretching over 3500 square miles. It was founded in 1872 making it the world’s oldest national park; welcoming over three million visitors a year. Below this national park lies a five-mile-deep reservoir of scorching magma, strengthened by a column of molten rock that has formed from hundreds of miles below. The current magma chamber is said to be in a state of dormancy signifying that there is a possibility for a future eruption. However, according to the US Geological Survey, the probability of Yellowstone erupting again is approximately 0.00014% each year and even then, a small eruption would be more likely. So, we’re safe for now.

Yellowstone has only ever had three huge eruptions; 2.1 million years ago, 1.3 million years ago and 640,000 years ago. The most recent was over 1000 times more powerful than the 1980’s Mount St Helens eruption which killed fifty seven people. A super-volcanic eruption from Yellowstone could be expected to kill at least 90,000 people immediately. To be considered a super eruption it must reach a magnitude 8 on the volcanic explosivity index – the most dangerous.

A magnitude 8 eruption would undoubtedly have significant consequences for the global climate. The eruption would induce a “nuclear winter” which occurs when gases emitted by the volcano (such as sulphur dioxide) rise high into the stratosphere and mix with the water vapour. This new mixture creates a layer of sulphate aerosols which block out any sunlight and plunge the Earth into darkness. For example, after the VEI-6 Mount Pinatubu 1991 eruption, the planet was cooled by one degree for 15 months; this is only a tiny eruption compared to what Yellowstone is thought to be capable of.  

Volcanic Explosivity Index (VEI)

A volcanic winter would in turn have a multitude of knock on effects. For example, the path and timings of monsoons would dramatically change, tropical cycles and weather patterns would become unpredictable resulting in the spread of waterborne diseases becoming highly erratic and thus harder to manage. Agriculture worldwide would also be negatively impacted. The toxic ash would make it impossible to grow crops on the worst hit states of America, and the price of what could be produced would rise sharply, causing food shortages and possibly even famines. A recent Federal Emergency Management Agency (FEMA) study calculated that the cost agriculturally for the US would be $3 trillion dollars which is 16% of the current US GDP.  Even though many of these effects would more likely only be temporary, it does not make them any less severe.

Reassuringly, shortly before an eruption a series of events will occur, providing some warning. Hydrothermal systems such as geysers and geothermal pools would heat quickly exceeding their boiling points and are likely to become highly acidic. Earthquake clusters would also start to appear, indicating hot magma rising to the surface. However, Yellowstone experiences between 700 and 3000 earthquakes a year, so these are not out of the ordinary. Once the magma reaches the surface, the top layer of rock would collapse indicating the start of an eruption. Large volumes of ash and lava would explode out of the crater to heights of above sixteen miles with the ability to sustain itself within the atmosphere for days. Arguably the most deadly, pyroclastic flows would travel a distance of up to sixty two miles which is roughly the length of the whole national park, killing everything in its path. Luckily an eruption of this size is said to be less likely than an asteroid impact.

Yellowstone is behaving as it has for the past 140 years and odds are very high that Yellowstone will be eruption free for the coming centuries

US Geological Survey

An important question resonating in many scientist’s minds today remains whether we can stop Yellowstone from erupting again or reduce the severity of a super-eruption. In 2017, NASA conducted an experiment led by engineer Brian Wilcox to see whether it would be possible to prevent another super eruption. This $3.5 billion hypothetical project involves cooling magma in the plume as it rises to the surface; reducing the heat and thus lowering the pressure that would normally build causing a volcano to erupt.  To achieve this goal, scientists intend to drill a series of boreholes along the area surrounding the national park. These boreholes would be drilled to nearly 10km below the surface making them some of the deepest in the world. Cold water would then be pumped into the boreholes allowing the rock surrounding the magma chamber to cool. This water would reach temperatures of 340°C as it makes its way around the chamber. By circling the water back through the boreholes the water would theoretically be able to drive an electric generator which could provide enough energy to power the entire US sustainably for hundreds of thousands of years.

There is a high chance that this project would work however, there is a low chance of anyone ever implementing it. Firstly, to cool Yellowstone to a safe temperature over 20 Gigawatts of energy would have to be generated, this would take over 16000 years. Secondly, this project is expensive – costing an estimated $3.46 billion, over 20% of NASA’s annual budget.  Thirdly the 1970 Geothermal Steam Act outlaws the placement of a geothermal plant in National Parks, and officially names Yellowstone in their list. They argue that a geothermal plant is an eyesore and can result in the disappearance of the geysers and hotsprings that add to the parks beauty and eccentricity. These features would disappear due to a reduction in pressure. Finally, and arguably the most serious concern is that when cooling the rock surrounding the magma chamber it is possible that the rock would fracture triggering the super eruption that the project was seeking to avoid. 

Keeping these volcanoes from devastating the human food supply and causing the deaths of 99 percent of all of humanity, that seems like a worthwhile thing to debate

Brian Wilcox engineer at the Jet Propulsion Laboratory

Wilcox and his supporting team hope that this geoengineering project will inspire future generations to discuss and develop ideas that will deter this super-volcano from causing mass destruction.

The most important take away from the prospect of a super-volcanic eruption is that humanity would survive it, although the world would most definitely change.

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