Major volcanic eruptions in Iceland have disrupted flights and affected communications throughout Europe and the Northern Atlantic in recent years, making headlines worldwide. Large volcanic eruptions are known to alter climate for extended periods of time by releasing massive clouds of ash and gases into the stratosphere which can lower surface temperature — by blocking the sun — or alter precipitation patterns.

Despite the broad geographic impact of such events, until now scientists believed that particles ejected from Icelandic volcanoes do not reach the European Alps due to the relatively large distance from the source. All ice cores collected in the Alps until now have shown no distinct layer of volcanic particles (tephra).

A new article just published shows that—with a large enough volcanic eruption, under certain atmospheric conditions—ash can reach the European Alps and be captured in the ice record. The article, first-authored by Harvard undergraduate Matthew Luongo ’17, is the result of a partnerships between the Initiative for the Science of the Human Past at Harvard (SoHP), and the Climate Change Institute (CCI) at the University of Maine, where Luongo was trained by world-renowned volcanologist, Professor Andrei Kurbatov.

This discovery indicates that SoHP-CCI researchers can now study how similar eruptions have affected climate and weather patterns for at least the last 2,000 years. Drilling and collecting ice cores from glaciers is a time-tested method of studying past climate conditions. This article analyzed a core from the Colle Gnifetti glacier, in the Swiss-Italian Alps.

A recent SoHP-CCI expedition collected the Colle Gnifetti core. The data obtained from it represent the highest resolution climate and pollution record in existence thanks to the use of a next-generation laser ablation ICP-MS system, at the W. M. Keck Laser Facility at CCI. With this record, SoHP-CCI scientists and historians are studying climate and pollution patterns from every year for the last two millennia, in most cases even reaching further precision within a year.

Using a scanning electron microscope with energy-dispersive spectrometry, Luongo analyzed filtered, insoluble particles obtained by melting ice chips. He identified six in a layer dated to the nineteenth century. Analyzing their geochemical signature allowed the authors to conclude that the ash originated from a single volcanic eruption, likely Icelandic in origin. Luongo narrated his experience in the SoHP blog.

This discovery of volcanic ash in the Colle Gnifetti ice core is highly significant because tephra, when geochemically matched to a certain eruption, allows precise dating of its ice layer. Other, similar volcanic markers within the core will help refine the dating of each layer. The study thus shows how the Colle Gnifetti ice record will contribute to our understanding of the climatic impact of volcanic eruptions in the past, informing our understanding of the future.

The research was funded by the Arcadia Fund, a charitable fund of Peter Baldwin and Elizabeth Rausing, the W. M. Keck Foundation, the National Science Foundation, SoHP, and CCI. It was published in Geochemistry, Geophysics, Geosystems, a journal of the American Geophysical Union.

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