New research from the University of St Andrews precisely dates one of the Earth’s largest known super-eruptions

Researchers from the University of St Andrews have been able to precisely date a volcanic super-eruption by identifying microscopic ash particles in polar ice cores. 

This new finding allows scientists to reconstruct the climate consequences of a super-eruption. Previously it was thought that super-eruptions may have triggered enough global cooling to cause an ice age, but a study published this week in Communications Earth and Environment has shown that this is not the case.

Findings showed that, although there would have undoubtedly been devastating short-term disruption to global climate systems, there was no long-term (centennial-millennial) climate catastrophe following the eruption, and global temperatures recovered to pre-eruptive conditions in the decades that followed

Research, led by the School of Earth and Environmental Science at St Andrews, dates the Los Chocoyos super-eruption of the Atitlán volcanic system in Guatemala to 79,500 years ago. Scientists determined this by finding tiny ash particles linked to an extremely large volcanic sulphate deposit in Greenland and Antarctic ice cores, which have precise age records. 

These ice cores also hold detailed climate records, helping researchers understand both the short- and long-term climate effects of the eruption. They also found tiny ash particles in marine sediment cores from the Equatorial Pacific that confirmed and supported the new ice core date. 

The study is an important step in further understanding of super-eruptions, the risk they pose, and the role they have in climate tipping points. 

Lead Researcher Dr Helen Innes said: “Our findings improve our understanding of how resilient the climate can be to supereruption-scale injections of stratospheric sulphate. Continuing to identify the largest volcanic eruptions in ice cores and assign high-precision ages is essential to our understanding of the risk that major stratospheric sulphate injections pose to global climate.” 

Super-eruptions are the largest volcanic eruptions known to have occurred on Earth. A super-eruption is an explosive volcanic eruption so massive that it causes a collapse of the volcano’s surface, creating a large crater-like depression called a caldera.  

They measure 8 or above on the Volcanic Explosivity Index (VEI) - a scale used by volcanologists and Earth scientists to define the size of eruptions, based on the volume of erupted material. VEI 8 super-eruption events are defined as erupting 1000 km³ of material, making them 100times greater than VEI 6 (eg. Pinatubo in 1991) and 10 times greater than VEI 7 (eg. Tambora in 1815) eruptions which have occurred in recent history.

As well as the colossal amounts of rock and ash erupted, super-eruptions inject vast volumes of gasses into the upper atmosphere, including sulphur gasses which react to form sulphate aerosols (particles) that reflect sunlight and act to cool the planet..  

Only a handful of super-eruptions are known to have occurred in the last 100,000 years, and none in recorded history. The most recent super-eruption was the Oruanui eruption of Taupō, New Zealand, around 25,500 years ago.  

As no known super-eruptions have occurred since then, the potential climate impact of the sulphate aerosols is not fully understood, leading to theories that super-eruptions and their effect on the climate could trigger long-term shifts to glacial conditions. 

Although recent studies have shown that they occur more often than we previously thought, they are exceptionally rare even compared to VEI 6 and 7 events. The chances of a super eruption happening in our lifetime is extremely low, with some studies estimating that they have a return period of around 17,000 years and suggesting the probability of one occurring in the next 100 years as low as 0.12%

ENDS