An Icelandic Fissure Sent a Toxic Haze Across Borders

1. Fissure Opening

On June 8, 1783, a volcanic fissure system opened in Iceland with violent phreatomagmatic explosions. Groundwater interacting with rising basalt magma generated extensive rows of boiling craters. Over subsequent days, the eruptions transitioned into Hawaiian-style lava fountains and continuous effusive flows. The event marked the beginning of an eight-month eruption period.

Volcanic columns propelled gases high into the atmosphere.

2. Volcanic Emissions

The fissure and adjacent Grímsvötn volcano poured out vast quantities of basalt lava and poisonous gases. Eruptions emitted millions of tons of fluorine compounds and massive quantities of sulfur dioxide into the atmosphere. Prevailing winds carried these aerosol compounds across the North Atlantic toward Europe. The resulting noxious fog became known as the Laki haze.

Sulfur emissions created a persistent dry aerosol veil over the Northern Hemisphere.

3. Icelandic Famine

The local consequences for Iceland proved disastrous for both agriculture and human survival. Fluorine contamination of grass led to fluorosis, killing a large majority of the island's livestock population. Milk yields plummeted across surviving herds. The loss of livestock triggered a severe famine that claimed thousands of human lives.

Approximately one-fifth of Iceland's human population perished in the aftermath.

4. Parish Accounts

Local clergy documented the advancing lava flows threatening communities and farmsteads. Parish ministers led congregations in prayer services as lava branches approached populated areas. These historical accounts provided detailed chronologies of the ongoing environmental collapse. Survivors recorded descriptions of darkened skies and persistent acid mists.

Church records captured the severe distress experienced by isolated rural settlements.

5. European Spread

The dense sulfuric haze drifted across Europe, reaching Bergen, Prague, Paris, and London within weeks. The fog was thick enough to disrupt shipping and obscure the sun. Inhaling sulfur dioxide caused respiratory distress as gases reacted with moisture in human lungs. Mortality rates rose perceptibly in affected British and European towns.

Outdoor workers experienced severe breathing difficulties during peak haze periods.

6. Severe Winters

The eruption was followed by reports of haze far beyond Iceland. Observers in Europe described unusual atmospheric conditions, and researchers later examined the eruption’s relationship to weather during that period. Those studies compare volcanic emissions with other influences. A particular cold winter or flood cannot be assigned to the eruption solely because it occurred afterward.

The effects in Iceland could be examined alongside records from other countries.

7. Global Weather Disruptions

Researchers analyzed evidence indicating that the eruption weakened monsoon circulations in Africa and Asia. Reduced precipitation led to low river levels and agricultural failures in distant regions. Famines and droughts affected populations in Egypt and India during the subsequent years. These disruptions coincided with regional climatic anomalies.

Global surface temperatures experienced measurable cooling following the emissions.

8. Contemporary Observations

Naturalists and scientists of the era recorded detailed observations of the unusual atmospheric phenomena. Observers in England and America documented the persistent dry fog and reddish sun. Correspondence between scientists detailed the blighting of crops and vegetation. These contemporaneous logs aided modern climatological research.

Naturalist records provided key empirical data for historical climate studies.

9. Societal Impacts

Crop failures and economic hardships persisted across Europe for years following the eruption. Historians have examined the role of these multi-year agricultural crises in fueling rural poverty. Subsequent severe weather seasons contributed to social pressures in various nations. The disaster left a lasting imprint on historical records.

Icelandic society adapted through recovery phases over the following decades.

10. Scientific Reassessment

The eruption continued into 1784 after months of lava and gas release. In Iceland, contamination of grazing land and livestock losses contributed to the subsequent famine. Haze and unusual weather were reported farther away, with later researchers examining how much was connected to the eruption. Those climate questions require separating documented observations from claims that the eruption alone caused every later European hardship.

The eruption ended, but the effects on livestock and food continued.

Sources

• Original narrative adaptation — CC BY-SA 4.0
• Wikipedia contributors — Laki (CC BY-SA 4.0)