Floods, Famine, Frosts … and Frankenstein

By Nicholas Klingaman

No one who lived through the extreme climate of 1816 understood what caused the months of seemingly endless rain in Europe, the June snowstorms in New England or the severe drought in the eastern U.S. that convinced many farmers to sell their land and move west. All they knew was the weather was against them. Many blamed God: religious revivals intensified in America, while in Europe, self-described prophets foretold the coming apocalypse. Others invoked natural forces: earthquakes, sunspots, icebergs, deforestation and changes in the Earth’s magnetic field. Meteorology was in its infancy – the first reliable weather forecasts were more than 130 years away – so few contemporary scientists could comprehend the changing conditions.

The true cause of “The Year Without Summer”, as 1816 would become known, lay halfway around the world on Sumbawa, an island near Java in Indonesia. Mount Tambora erupted in April 1815 with such force that British soldiers several hundred kilometres distant on the island believed they were under assault from enemy cannons. The eruption was one of the four strongest of the last 10,000 years, 100 times more powerful than the 1980 eruption of Mount Saint Helens in the US. Within 24 hours, the ash cloud covered an area the size of Australia. In Indonesia, 70,000 – 90,000 people died in the eruption and its aftermath, most from famine after the ash poisoned crops.

For the climate, the eruption’s height was more important than its power. Tambora’s plume of ash and gas extended more than 25 kilometres into the atmosphere, reaching the stratosphere. When volcanic plumes are limited to the troposphere (below 15-20 kilometres), rain droplets remove the ash, dust and sulphuric acid within weeks. Clouds rarely reach the dry stratosphere, however, so particles can remain for years before they grow large enough to fall. Tambora threw about 55 million tons of sulphur dioxide gas into the stratosphere, where it formed more than 100 million tons of sulphuric acid. Within months, strong stratospheric winds dispersed the acid droplets around the globe.

Because the droplets reflected and scattered sunlight, they may have appeared as a thin veil or haze, barely perceptible to the naked eye. Many never noticed it. The veil reflected only one half of one percent of the sunlight across the globe, but that cooled the average global temperature by 1-2ºC, making 1816 the second coldest year in the last millennium, after 1601 (which was also due to a volcanic eruption). Our planet’s climate is finely balanced: small changes in the input and output of energy can dramatically alter weather patterns, magnifying impacts on human life and the environment.

Western Europe and eastern North America cooled much more than the global average — at least 3ºC — because the falling temperatures altered the path of the Atlantic jet stream, the “conveyor belt” of winds that steer storm systems.  The summer jet stream normally flows north-east from the Gulf of Mexico, bringing warm, humid air to the U.S. east coast and keeping most of Europe fairly dry (see Figure 1).  In 1816, however, the jet stream slowed and developed “U”-shaped bends, winding its way north and south instead of east and west.

2014 07 24 Nick Klingaman - year_without_summer_jet_stream

Figure 1. Displacements in the polar jet stream during summer 1816.

Instead of mild Gulf air, New England suffered cold Arctic blasts from Canada. As much as 30 cm of snow fell during a powerful early-June storm. Ground frosts plagued the region throughout the summer. Without summer thunderstorms to bring rain, crops failed in a drought that continued through autumn. In western Europe, the jet stream dipped far south, bringing a succession of strong wind and rain storms more typical of autumn and winter than summer.  The wet and cold weather triggered a typhoid epidemic in Ireland, the first in the western world, that killed more than 60,000. In Switzerland, it rained on 130 of 152 days between April and August. Flooded rivers created thousands of refugees, who roamed from town to town in search of food and charity, finding little of either. Trapped indoors by the relentless poor weather, the novelist Mary Shelley, her poet husband Percy and their friend and fellow poet Lord Byron told ghost stories to one another, a popular pastime of the day. It was there, surrounded by the dark, gloomy conditions, that Mary conceived the idea for Frankenstein.

Many governments reacted slowly to the mounting catastrophe. Fearing that a spike in grain prices would trigger a revolt, and mindful of the recent French Revolution, European governments restricted grain exports and suppressed news of poor harvests. Neither policy helped. Eventually, they were forced to offer some charity to the poor – the first instance of widespread, systematic welfare assistance by western governments.

While Tambora’s eruption produced disastrous impacts on regional weather, human health and society, mercifully its effects were relatively short-lived. After another, less extreme, cold summer in 1817, most of the stratospheric acid veil had dissipated. It would not be until the mid-1950s, while monitoring the Cold War nuclear tests, that scientists verified the effects of stratospheric particles on our climate – the “nuclear winter” scenario that resembles the effects of an eruption – and established what caused the extreme climate of the Year Without a Summer.

Nicholas Klingaman is the co-author of The Year Without Summer, recently published by St Martins Press

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