Climate models indicate more storms and extreme cold events following high-latitude eruptions

A major eruption here in Iceland or elsewhere in the Arctic region is likely to be followed by a temporary increase in storms and extreme cold events, according to models developed by a team of Icelandic and international scientists. The models were designed to help us learn more about how high-latitude sulphur-rich eruptions affect the weather and climate in the North Atlantic region. The team’s findings were recently published in the journal Atmospheric Chemistry and Physics. 

Generally speaking, sulphur particles disrupt thermal atmospheric processes, which can have a wide-ranging impact on, for example, stratospheric winds and prevailing weather systems on Earth. However, there has been a lack of precise data, for example satellite data, about climatic response and the behaviour of volcanic particles following major eruptions in the Arctic region. The scientists behind the study point out that it is probably only a matter of time before such an eruption occurs, based on increased activity observed in major volcanic systems in Iceland over the past decade, e.g. at Bárðabunga, Öræfajökull, Hekla, Katla and the Reykjanes peninsula. 

Climate models are an effective way to simulate the impact of an eruption

“It is important that we are prepared for the potential consequences a major eruption could have for our climate here in the North Atlantic. Climate models are very useful here, because we can use them to very precisely simulate the physics that control climate systems and how different elements interact. Models allow us to do all kinds of climate experiments using certain parameters, such as the size and length of an eruption, to conduct research while we wait for a real eruption to compare our findings with,” says Hera Guðlaugsdóttir, postdoctoral researcher at the UI Institute of Earth Sciences, who has been working on this project for the past few years and is the first author of the article in Atmospheric Chemistry and Physics. 
Other members of the research team were Guðrún Magnúsdóttir, professor at the University of California Irvine, and Yannick Peings, research scientist at the same university, where Hera also studied on a Fulbright scholarship in 2022-2023. Davide Zanchettin, professor at Ca'Foscari University of Venice, also contributed to the article..

Exploring the impact on the first three post-eruption winters

An eruption that emits large volumes of sulphur compounds into the atmosphere could set off processes within the climate system that could affect the weather or climate in the short term (seasons or years) or long term (decades or centuries). For this study, the scientists carried out experiments using climate models to explore what impact a six-month eruption at 65° North would have on the climate system in the Northern hemisphere. The scientists assumed a comparable volume of sulphur dioxide (SO2) as observed in the 1991 eruption at Pinatubo in the Philippines, around 14 Tg of SO2 over a period of six months. In comparison, the Laki eruption in 1783 is estimated to have produced a total of around 122 Tg, while the 2014 Holuhraun eruption produced around 6-7 Tg. 

“For this study, we focused on the impact an eruption would have on the stratosphere over the first three post-eruption winters. This is because the stratosphere contains the polar vortex, which is believed to determine climactic response at the surface following eruptions at either high or low latitudes. We looked at anomalies in stratospheric winds and temperatures, but also, for the first time, explored whether changes in planetary waves caused by an eruption could affect stratospheric winds. Due to the chaotic behaviour of the atmosphere, we run the same model setup 20 times for each experiment and use statistics to evaluate the average response,” explains Hera.

“We have also observed an unusual increase in the frequency of sudden stratospheric warmings, which will require further research, since they can weaken stratospheric winds, leading to extreme cold events on the surface in the Northern hemisphere. As far as we know, this is the first time a potential link between eruptions and sudden stratospheric warmings has been identified,” says Hera.

Her previous research has shown that high-latitude eruptions can cause more frequent low pressure areas in Iceland, which is closely related to weakened stratospheric winds. “So these findings support that idea, although there are still many unanswered questions.”

Findings could be used for eruption risk assessments

Hera hopes that the findings can be used to produce a kind of eruption risk assessment for communities here in Iceland and elsewhere in the North Atlantic region. “This would help us prepare for a temporary increase in storms and extreme cold events, changes in precipitation and/or prevailing weather systems following a major high-latitude eruption,” she says.

She also emphasises that sulphur particles from volcanic eruptions cause temporary changes to the planet’s localised thermal management. “So we can also think of eruption experiments as another tool to help us better understand how interaction between the atmosphere, ocean, and sea ice can lead to localised human-driven climate change.”

See here to read the article in Atmospheric Chemistry and Physics.