Study links volcanic eruptions in 540s, 1450s, 1600s to global cooling events

A new study led by the University of St Andrews, in collaboration with international researchers, reveals that historical volcanic eruptions, particularly in high latitude regions, have caused significant yet transient global cooling effects. Published in the Proceedings of the National Academy of Sciences, the research utilized sulfur isotopes from ice cores to trace the climatic impact of volcanic eruptions in the Northern Hemisphere, particularly during notably cold decades like the 540s, 1450s, and 1600s.

Volcanic eruptions have long fascinated scientists and historians alike, but a recent study by the University of St Andrews and its international partners has shed new light on their climatic impacts. The research, published in the Proceedings of the National Academy of Sciences, focuses on how eruptions, especially those at high latitudes, have historically led to short-term global cooling.

The team, led by Dr. Andrea Burke from the School of Earth and Environmental Sciences at St Andrews, along with colleagues from Switzerland and the U.S., used a novel approach to understand these phenomena. By studying sulfur isotopes in ice cores extracted from Greenland and Antarctica, the researchers were able to trace the climatic effects of volcanic eruptions. These isotopes act as a fingerprint, revealing the fraction of sulfate that reached the stratosphere following volcanic events.

One of the key findings of the study is the correlation between unusually cold decades and large volcanic eruptions. Notable periods such as the 540s, 1450s, and 1600s were marked by significant cooling, now linked to these eruptions. The volcanic sulfate particles, injected into the upper atmosphere, were responsible for reflecting incoming sunlight, thus reducing global temperatures.

However, the origins of these eruptions and the precise amount of sulfate they released remained uncertain until this study. The research team’s analysis suggests that the amount of sulfate reaching the stratosphere from these high-latitude eruptions may have been about half of what was previously estimated. This finding indicates that summer temperatures in the Northern Hemisphere are highly sensitive to these volcanic events.

Dr. Burke highlighted the broader implications of their findings, stating, “Our data show that when Earth’s climate gets altered, other parts of the climate system can kick in to strongly amplify this initial change.” She emphasized the particular vulnerability of high-latitude regions to these amplified climate changes, a concern given the rapid environmental transformations occurring in these areas today.

The study also sheds light on the role of climate feedback mechanisms, such as changes in sea ice extent and ocean heat content, in amplifying global climate changes. This underscores the interconnectedness of various elements within the Earth’s climate system and their collective response to natural events like volcanic eruptions.

References:

¹ Study shows historical volcanic eruptions triggered short-term global cooling – University of St Andrews – November 7, 2023

² High sensitivity of summer temperatures to stratospheric sulfur loading from volcanoes in the Northern Hemisphere – Andrea Burke et al. – PNAS 2023 – DOI: 10.1073/pnas.2221810120

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