The Summer That Never Came

On the evening of 10 April 1815, a mountain on the Indonesian island of Sumbawa stopped being a mountain. Tambora had stood something over four thousand metres; by morning it was a caldera, and roughly a third of its height was in the sky. The eruption rated a 7 on the Volcanic Explosivity Index — Ultra-Plinian, the most violent class yet confirmed in the historical record, and still the most recent of its magnitude. It threw out at least thirty-seven cubic kilometres of rock.

The rock was not the problem. The problem was the sulfur.

A veil at forty thousand feet

Ash is heavy and impatient; it falls out of the air within weeks. Sulfur dioxide is neither. Driven high enough to punch into the stratosphere — above the weather, above the rain that would otherwise scrub it out — it combines with water into a fine haze of sulfuric acid droplets. That haze does not wash away. It drifts, spreads along the circulation of the upper atmosphere, and reflects sunlight back into space before it can reach the ground.

Within a year the veil had wrapped the planet. Average global temperatures fell by somewhere between 0.4 and 0.7 °C.

That figure is worth sitting with, because it looks trivially small and was not. Half a degree, averaged across a whole planet and a whole year, is not felt as half a degree. It is felt as a growing season that ends three weeks early, in the particular valley where you happen to farm.

1816

In New England, frost killed crops at higher elevations across Massachusetts, New Hampshire, Vermont and upstate New York through May. On 6 June, snow fell on Albany, New York, and on Dennysville, Maine. Farmers replanted, and lost the second planting too. The year entered American memory under a set of bitter nicknames — the Poverty Year, Eighteen Hundred and Froze to Death.

Europe had it worse, because Europe was already exhausted. The Napoleonic Wars had ended at Waterloo ten months before Tambora’s haze arrived, leaving the continent full of demobilised men and depleted granaries. The summer of 1816 was the coldest recorded in Europe between 1766 and 2000, and what followed was the worst famine of the nineteenth century.

	1815	1816
Oats, per bushel	12¢	92¢
European summer	ordinary	coldest in 234 years of record
Typhus deaths, 1816–1819	—	over 65,000

Oats rose nearly eightfold. Bread riots ran through Switzerland, France and the British Isles. Typhus spread outward from Ireland and killed more than sixty-five thousand people over the following three years. The dying was not done by the volcano; it was done by hunger, and by the diseases that follow hunger into a weakened population.

The wettest summer on the lake

That June, a small party of English writers had taken houses beside Lake Geneva. Lord Byron was at the Villa Diodati; Percy and Mary Shelley were nearby, with Byron’s physician John Polidori. They had come for an Alpine summer and found instead what Mary Shelley remembered as incessant rain, which kept them indoors for days at a stretch.

To pass the time, Byron proposed that each of them write a ghost story.

Mary Shelley — eighteen years old — began the one that became Frankenstein; or, The Modern Prometheus. Polidori began the one that became The Vampyre, the story that pulled the vampire out of folklore and installed him in the drawing-room as an aristocrat. Byron himself, in July, wrote “Darkness”:

I had a dream, which was not all a dream.
The bright sun was extinguish’d, and the stars
Did wander darkling in the eternal space.

It is usually read as apocalyptic invention. It is closer to reportage.

No oats, no horses

There is a stranger consequence still. A horse eats oats, and in 1816 oats were eightfold dearer, where they could be had at all. Across Europe horses were slaughtered or starved, and the cheapest form of personal transport in existence abruptly became unaffordable.

In Mannheim, a civil servant named Karl Drais had been tinkering with the problem of moving a person without an animal. In 1817 he demonstrated the Laufmaschine — the running machine, later the draisine or velocipede: two in-line wheels, a steerable front, a seat, and no pedals. You pushed it along with your feet. It is the direct ancestor of the bicycle, and it arrived precisely when the alternative had died in its stable.

---

None of this was legible at the time. No one in Albany or Mannheim connected a failed harvest to an island most Europeans could not have placed on a map; Tambora’s role was not firmly established until the twentieth century. What people had instead was an unaccountably cold year, and they made of it what they could — a novel, a poem, a machine, and an enormous number of graves.

The thing worth keeping is the shape of the causation rather than the details. A single geological event, lasting days, altered the chemistry of the upper atmosphere for years, and the consequences surfaced as literature and as transport engineering in places thousands of kilometres away, through no path anyone could see while walking it.