Explaining the Summer of 1783

I looked up the Massachusetts newspaper coverage of Europe’s unusual atmosphere in 1783, quoted yesterday, after reading Katrin Kleemann’s online article from a few years back, “Speculating About the Weather: The Unusual Dry Fog of 1783.”

Kleemann wrote:

…in the summer of 1783, Europeans had more than enough reasons to be concerned with the weather. A peculiar dry fog with an odd sulfuric smell cloaked Europe and remained for months, with neither wind nor rain managing to disperse it. The fog was not the only oddity these individuals were facing that summer: The sun had a blood red color when it set and rose; an unusual number of thunderstorms seemed to pass through; meteors were visible over western Europe, earthquakes occurred in Italy, and a new island emerged from the sea off the coast of Iceland. Speculation was rife as to the cause of all this.

Hekla, an Icelandic volcano, known in Europe since medieval times as the gate to hell, was thought to be a potential culprit. When referring to historical maps of Iceland, Hekla is usually pictured as erupting. Famously, Benjamin Franklin suggested that Hekla or Nyey, the newly emerging island, might have caused the dry fog. However, what is often forgotten in this context is that in the same paragraph, Franklin suggested “great burning balls” (meteors) might alternatively have caused it.

At the time a very fashionable explanation was electricity: Lightning was believed to fertilize the soil when it hit the ground. The numerous thunderstorms of the summer quickened the spread of the lightning rod, which had not yet had its breakthrough. The lightning rod was believed to withdraw the beneficial electricity from the atmosphere, which—so the theory went—caused the dry fog, as sulfuric odor had previously been consumed by the “electrical fire.”

There was yet another story making its rounds in the newspapers in July 1783: Not just one but two volcanic eruptions were described within the German territories. The Cottaberg near Dresden as well as the Gleichberg mountains near Hildburghausen were said to have roared to life and to be spitting fire. Both mountains are actually of volcanic origin—however, their last eruptions occurred 25 and 15 million years ago, respectively. The reports were retracted a few weeks later.

The most popular theory of the time suggested that earthquakes in Italy and this dry fog were directly related: people believed the earthquakes had opened a crack in the Earth, which released sulfuric odor from the Earth’s interior into the air. The concept of a subterraneous revolution plausibly explained the sulfuric smell, the fog, the earthquakes, and the newly emerging island.

As Kleemann related, the answer to the atmospheric mystery did lie in Iceland, but it took a long time to come out. Eleven years after that odd summer, an Icelandic scientist named Sveinn Pálsson (1762-1840, shown above) described the volcanic fissure now called Laki. That system had erupted from June 1783 to February 1784, emitting huge amounts of basalt lava and poisonous clouds. The effects in continental Europe were nothing compared to what happened locally, as more than half of Iceland’s livestock died, followed by most of the crops, followed within a few years by about a quarter of the humans from famine.

Despite all those effects, Pálsson’s report wasn’t published by the Danish Society of Natural History but simply filed away. A century later, the eruption of Krakatoa confirmed that massive volcanic activity could affect the atmosphere all over the planet. People rediscovered what Pálsson had written. His manuscript was finally published in full in 1945, explaining the odd summer of 1783.

(Kleeman’s article appeared on the website of N.I.C.H.E., which is both the Network In Canadian History & Environment and the Nouvelle Initiative Canadienne en Histoire de l’Environnement. Coming up with a name to justify a good acronym is tough enough, but doing so in two languages at once is a real feat.)