New research by a team of scientists from the US, Democratic People’s Republic of Korea (DPRK, the formal name for North Korea) and the UK, including Birkbeck geophysicist Dr James Hammond published in the journal Science Advances on 30 November 2016 provides surprising new evidence about the emissions of an ancient volcanic eruption: that of Mount Paektu (which straddles the border between China and DPRK) in 946 AD. This was one of the largest eruptions of the last two millennia and eruptions of this scale usually cause extreme climatic effects as they pour sulphur into the atmosphere, which turns into particles that reflect the sun and thereby lower the Earth’s temperature. Researchers can estimate the climatic effects of ancient eruptions using ice cores – which often preserve the sulphur particles when they fall to Earth; tree ring records; and rock. In the case of the Mount Paektu 946 eruption, ice cores and tree ring records provide little evidence of a decrease in global temperatures, leading scientists to believe that little sulphur was emitted in the eruption. However, the new study shows that, in contrast to earlier estimates, the 946 eruption did eject large volumes – up to 45 megatons – of sulphur into the atmosphere.
The team of scientists looked at rocks from Paektu and modelled the way in which sulphur and other elements crystallised during the magma’s cooling phase. They then compared the amount of sulphur preserved in the rock with the amount of other elements, and from this could ascertain how much sulphuric gas had percolated out of the magma before the eruption occurred. The results indicated that in the case of the 946 eruption 45 megatons of sulphur had already been ejected into the atmosphere.
The team suggests reasons why the eruption apparently caused little climatic disruption, despite the high levels of sulphur: the high latitude of the volcano and the time of year of the eruption. Dr Kayla Iacovino, a volcanologist at Arizona State University and lead author on the study, explains: “Emissions from high latitude volcanoes tend to stay within the same hemisphere and have a smaller impact on global temperatures. Additionally, the sulphate particles from high latitude volcanoes tend to fall from the stratosphere more quickly than those from eruptions in tropical locations. Finally, the fact that the eruption occurred during the winter means that there would have been less sun for the sulphate particles to reflect, and therefore less of an overall impact.”
Dr James Hammond, lecturer in geophysics in Birkbeck’s Department of Earth and Planetary Sciences, said: “This paper shows how important it is to study volcanoes no matter where they are. This volcano, responsible for one of the largest eruptions on record was thought to have had minimal sulphur release. Rather, we suggest it could have been one of the largest on record. This is the second paper from our collaboration with DPRK scientists and we are currently planning new projects to understand this enigmatic volcano”
Dr Hammond recently published an article about scientific diplomacy and the challenges of working in areas where there are strained relationships within the international community.
Listen to Dr Hammond speak about the scientific and diplomatic considerations of conducting this research (starts 11min 28 secs in).
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[Image: Paektu crater. Credit: Kayla Iacovino]
Published: 02 December 2016