Scotland’s weather and climate 1783–85: a time like no other

Professor Alastair Dawson and Dr Martin Kirkbride, University of Dundee

Reconstructing past weather using archived instrumental records and weather diaries has a significant role in providing an accurate understanding of natural climatic variability in pre-industrial times. The first reliable mercury thermometer was invented by Daniel Fahrenheit in 1714, and by the 1780s several daily instrumental records were kept in Scotland, mainly on lowland estates and in the New Town of Edinburgh. A few of these have been analysed in detail, but other valuable weather records undoubtedly remain to be studied.

The value of historical weather records is that they can be used to construct very highresolution time series of past weather from daily data. When combined with similar data from across Europe, they enable the reconstruction of regional weather patterns over wide areas. These can show the trajectory and intensity of specific cyclones associated with disastrous gales, or persistent blocking anticyclones which caused prolonged periods of intense winter cold or summer heatwaves, as exemplified by the pioneering work of Hubert Lamb, John Kington and others.

The explosion of scientific inquiry that accompanied the Scottish Enlightenment coincided with some notable climatic events within the socalled Little Ice Age. Foremost among these was a period of severe winters and hot summers following the enormous eruptions of the Laki fissure in Iceland, commencing in June 1783. Our understanding of this event exemplifies the scientific debate about the influence that major volcanic eruptions have had on the Earth’s climate.

The start of June 1783 was, for most Scots, beautiful and warm – not a cloud in the sky. People could forget their hardships for a few days. Those who were outdoors could savour the warmth of the sun. Of course, life was tough, hunger was never far away, and it was always a struggle to put food on the table, but the balmy weather could at least provide some respite. For many, there was the talk of a new life in the New World. The American War of Independence had ended and there had been a recent upsurge in the numbers of Scots boarding the emigration ships. But the weather and climate were about to change.

On 8th June, a volcanic eruption started along the Laki fissure in Iceland. In the following days, clouds of ash and sulphurous gas darkened the Icelandic skies. Apart from the volumes of ash entering the atmosphere, the amounts of sulphurous gas were exceptional: the most recent figures place the amount of sulphur dioxide produced over the whole eruption period as around 122 megatons. In Iceland the effects were devastating, with the loss of most of the island’s cattle, ponies and sheep, as well as a fifth of the population. A committee was appointed in Copenhagen to devise means for relief for Iceland, and a plan was even debated of evacuating the population and resettling them in Denmark.

Across Scotland, 8th June 1783 was much like any other day. No one had any idea that a huge volcanic eruption had taken place in Iceland. Around a week later, there were indications in Scotland that something unusual had happened. In Edinburgh, Dr Pursell wrote in his diary that the sky had started to turn very dark. A few days later, he and other observers started to document a haze that had descended over the country. The anticyclone that had been in place throughout the summer of 1783 was big; in fact it covered most of Europe. As the sulphurous haze spread across central Europe, large numbers of people experienced a range of respiratory illnesses. The estimates of the number who died from the effects of the haze are wide-ranging, some suggesting a figure as high as 20,000 people in England alone. Almost nothing is known of the effects of such large quantities of sulphate gases in Scotland’s atmosphere, but there are faint clues. One of these is from the diary of Janet Burnet near Inverurie, who describes how the leaves of her crops during July turned yellow and withered. Another clue is how the year 1783 is known in Gaelic as the bliadhne na sneachda buidhe or the year of the yellow snow, a reference to sulphurous atmospheric precipitation.

The eruptions of Laki continued intermittently until February 1784 but were most intense during June and July 1783. Across Scotland there were numerous thunder and lightning storms. For example, the Scots Magazine reports how “on Wednesday, July 2nd the thunder was general, more or less, over almost all England and Scotland, for a course of near 600 miles. In Dumfriesshire it was heard about two o’clock in the afternoon, and continued till eight, with awful flashes of lightning, accompanied with amazing quantities of rain. In Alloa, the storm was uncommonly alarming in the evening. The lightning struck a woman, her daughter, a young boy, and a dog. The girl was scorched all over the body.” Similar lightning storms took place throughout July, although diminishing in frequency and intensity during August. During 1783, people in Shetland were struggling to find food following a famine a year earlier. The crops had failed, much of the livestock had been used for food, while many people survived by eating whelks, limpets and a plentiful supply of herring. Matters were to deteriorate across much of Scotland as the winter of 1783–84 approached. It was to prove to be one of the coldest winters ever experienced in recent Scottish history. It was stormy also, with Peterhead and Wick just two of many harbours that were destroyed along the coast of eastern Scotland. Many descriptions tell of coastlines strewn with shipwrecks and vessels driven ashore.

The following winter of 1784–85 was no better. The Scots Magazine summarised, “this winter-season, from the first fall of snow on Oct 7th 1784 (till the start of April)… lasted 177 days, and, if about twelve days towards the end of January be excepted, the whole of this period was frosty or snowy, or both.” Temperatures in Edinburgh fell below freezing for approximately 120 days. Shetland continued to suffer, with ships loaded with oatmeal sent there from ports as far away as Newcastle. On one of the ships, 858 bushels of barley and six tonnes of oatmeal had been paid for by public subscription.

It was not until the summer of 1785 that people could seek some relief from the weather extremes. Numerous reports describe it as moderately warm and followed by a mild winter, damp conditions with little frost and snow. Scotland was beginning to emerge from a period of exceptional hardship. But the spectre of famine and hunger was going to take a long time to fade; indeed, the hunger faced by the poor throughout the latter decades of the 18th century never really went away. It has always been recognised that the exceptionally severe winters of 1783–84 and 1784–85 brought devastating effects on the people of Scotland. But it has never been understood why two such dramatically cold winters took place one after the other. One view is that they simply represented part of natural climatic variability, and the pattern of pressure systems which drew in the cold continental air was unrelated to the Laki eruptions. The alternative view, one which is generally supported by computer modelling, is that they were a direct consequence of the Laki eruptions. Perhaps we will never know for sure.