AN 18th-century volcanic eruption spread a sulphurous haze across Scotland and turned crops black and leaves yellow, research suggests.

A team at Dundee University looked at the impact of a series of volcanic eruptions that started at the Laki fissure in Iceland on June 8, 1783.

Across northern and central Europe, people were unaware that an eruption had taken place, until a few weeks later, when 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, with famines recorded as far away as Egypt.

The eruptions of 1783 were 10 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 more than 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 by studying the climate in Scotland in the years after the eruption.

They 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 Kirkbride. “Researching these diaries makes an invaluable contribution to how we understand the impact.”