The remarkable frost of June

A bitter frost and ice discovered in tubs – all near Bury in the summer of 1783. Dr Keith Cunliffe, of St Edmundsbury Borough Council Heritage Service, explores what might have caused the strange climatic conditions.

What is the connection between this portrait of the Rev Sir John Cullum, by Angelica Kauffman (on display at Moyse's Hall Museum, in Bury St Edmunds), the Laki Fissure, in Iceland, and the 'remarkable frost' of June 1783?

You can discover the answer to that question in a forthcoming episode of the BBC's Timewatch, scheduled for screening later this year, but here is the short version of the story.

Throughout Europe in the summer of 1783, there were reports of strange and unaccountable atmospheric phenomena. These spread as far as North America, where Benjamin Franklin described a mysterious 'fog'.

These effects were even more dramatic in East Anglia and it so happened that, living at Hardwick Hall, just outside Bury, was the Rev Sir John Cullum, a keen naturalist and antiquarian.

This portrait was probably painted when he was about 40.

Sir John was a Fellow of the Society of Antiquaries and in 1784 he published a History and Antiquities of Hawstead and Hardwick in the County of Suffolk. He must have been a busy man for, also in 1784, he sent an account of the 'remarkable frost on June 23, 1783' to his friend Sir Joseph Banks, the famous botanist and president of the Royal Society.

This was published and provides a vivid account of the extraordinary climatic conditions that summer.

Sir John notes that at 'about six o'clock that morning, I observed the air very much condensed in my chamber window and, upon getting up, was informed by a tenant that, finding himself cold in bed, at about three o'clock in the morning, he looked out of his window and, to his great surprise, saw the ground covered with a white frost.

I was assured that two men at Barton, about three miles off, saw, in some shallow tubs, ice of the thickness of a crown-piece.'

Sir John's vegetable garden did not escape either, for he noted plants appeared 'exactly as if a fire had been lighted near them, that had shrivelled and discoloured their leaves'.

But what was the cause of this frost and the 'havoc' which Sir John Cullum reports?

Nobody in 1783 would have made the connection, but in June that year a major eruption took place in Iceland, creating the Laki Fissure and causing devastation on the island, with great loss of life.

Huge quantities of acidic material were ejected into the atmosphere and subsequently deposited over much of Europe.

This helped to create the 'dry mist' which not only darkened the sun but caused damage to plants which, from the descriptions given by Sir John Cullum and others, is consistent with exposure to acid rain.

Not surprisingly, no-one in 1783 knew quite what to make of this. Some of Sir John's observations are questioned today; was there really ice on water tubs in mid summer or was it an effect of sulphur and other chemicals spewed out by the eruption?

It is only now, through the work of palaeo-climatologists,we can begin to reconstruct the effects of one of the greatest eruptions in history and to provide an answer to Sir John Cullum's puzzlement as he surveyed his devastated vegetable garden.