First study of Scotland’s ‘volcanic weather’ published

Researchers at the University of Dundee have published the first study looking at how Scotland was affected by one of the most important climatic events of the last millennium.

On 8 June 1783, a series of volcanic eruptions started at the Laki fissure in Iceland that were to last until the following February. Across northern and central Europe people were unaware that an eruption had taken place until, a few weeks later, a choking sulphurous haze started to arrive.

Tens of thousands died from respiratory failure because of the sulphuric gases that lingered in the air, and many more died during the extremely cold winter that followed. Famines recorded as far away as Egypt and Japan have been attributed to Laki, while it has even been claimed that crop failures in Europe contributed to the outbreak of the French Revolution.

The eruptions of 1783 were ten times the size of Iceland’s 2010 volcanic eruption, which led to an aviation shutdown across Europe.

While some scientists believe that the very cold post-eruption winters were a result of Laki, others have argued that these events likely resulted from natural climatic variability unconnected to the eruption. Laki has been implicated in over 20,000 excess deaths in England at this time but until now very little was known about its impact in Scotland.

Professor Alastair Dawson and Dr Martin Kirkbride, from the University’s Geography and Environmental Sciences department, have addressed this gap by studying climate and air quality in Scotland in the years following the eruption.

They made use of contemporary instrumental records and diaries which provide rare eye-witness records of what happened in Scotland at this time. The information was compared with sophisticated computer model simulations of the event.

The Dundee team found the extremely low winter temperatures from 1783-86 to be strongly associated with the natural variability of climate and not simply related to volcanically-forced cooling. This challenges the hypothesis that the Laki volcanic eruptions on their own were responsible for the sustained lowering of air temperatures over the three successive winters that followed.

“The winter that followed Laki was as severe as any on record for Scotland but, from the data we gathered, it is impossible to say there was definite cause and effect,” said Dr Kirkbride.

“Researching these diaries, held at the National Library of Scotland and National Records Scotland, makes an invaluable contribution to how we understand the impact of the Laki eruptions in Scotland.

“They record temperature, wind direction, atmospheric pressure, hours of sunshine and precipitation and we have used this information to gain a deeper understanding of what happened in Scotland climatically as a result of Laki.

“It’s significant that the chronology and meteorology of haze occurrence in Scotland during the summer of 1783 has clear implications for any future Laki-type eruption, which has the capacity to create a major public health crisis across Europe.

“As the COP26 United Nations climate change summit approaches in Glasgow this November, we would be well advised not to forget the significant impacts that major volcanic eruptions may have on climate change and public health.”

The archive sources analysed by Professor Dawson and Dr Kirkbride include weather diaries from Dalkeith and Edinburgh in the central lowlands and Fochabers in Morayshire. These are supplemented by the diary of Janet Burnet of Aberdeenshire, who described daily weather phenomena and farming observations.

The Fochabers and Dalkeith diaries represent Scotland’s oldest instrumental weather records and two of the oldest daily weather records in Europe.

They demonstrate that the sequence of changes in weather and air quality took place almost simultaneously at all locations, despite Fochabers being located around 300 km north of Edinburgh and Dalkeith.

They note that on June 15, a week after the start of the Laki eruption, ‘dark’ and ‘gloomy’ conditions occurred across eastern and northern Scotland and persisted until June 21.

Following a three-day interval of fine weather, a remarkable sulphurous haze arrived on June 24 and persisted for the rest of the summer. As the summer progressed, air pollution episodes became shorter, less frequent and more influenced by the vagaries of daily weather.

Professor Dawson said, “This was the period of the Scottish Enlightenment, when families of means would purchase barometers and thermometers and indulge in meteorology as a hobby. The diaries are a result of this, and a wonderful resource that has enabled us to study historical Scottish climate change based on data never before seen.

“Janet Burnet’s diary talks of hazy, foggy days and the leaves turning yellow and the crops black. In the western Highlands many referred to the winter of 1783-84 as the Bliadhne nan Sneachda Bhuidhe ‘the year of the Yellow Snow’.”

The paper is published in the journal The Holocene.