A Gloomy and Tedious Period – Who First Connected the Dots?
On the night of the 6th water froze an inch thick – on the night of the 7th and the morning of the 8th, a kind of sleet or exceeding cold snow fell, attended by high wind and measured in places where it drifted 18 to 20 inches in depth. Saturday morning (8th) the weather was more severe than it generally is during the storms of winter. It was indeed a gloomy and tedious period. North Star (Danville, Vermont), 15 June 1816.
Few summers have garnered more attention than the summer of 1816, known as the “Year Without a Summer”. Though no one at the time knew it, the reason for the anomalously cold temperatures and bizarre weather was the largest eruption of a volcano in recorded history. The April 1815 eruption of Mount Tambora on the island of Sumbawa, in what is now Indonesia, caused a devastating global lowering of average temperatures which persisted for three years while the eruption continued.
A crater approximately 4 miles across and 2,300 feet deep was left after the main eruption and an estimated 100,000 people died on nearby islands. During the months following, temperatures globally declined on average anywhere from .7° – 1.3° F. In many parts of the world, the lower temperatures were accompanied by drought or bizarre rain events; snow and frost in midsummer; and dramatic severe weather. As volcanic ash continued to eject into the stratosphere and disperse around the globe, crops failed, fishing was disrupted, and famine ensued. As described above in the Vermont North Star newspaper of June 15, 1816, it was ‘indeed a gloomy and tedious period’.
The details of the eruption and its aftermath, including its influence on such disparate human activities as art, literature (the year Frankenstein was created), agriculture, human migration, distilling and medicine (think epidemics) are fascinating but will not be discussed in this post and can be easily found online. What seems interesting and not an aspect often explored is: exactly when did everyone finally figure out what had caused the great cold spell?
Not surprising, it seems that the clever and ever curious founding father, Benjamin Franklin, had been the first to hit upon the notion that volcanic ash suspended in the atmosphere (1) might cause the weather to cool – even on the other side of the world. He published his hypothesis in an article, Meteorological Imaginations and Conjectures, in a small 1784 pamphlet, Manchester Literary and Philosophical Society Memoirs and Proceedings, in which he suggested that the cold summer of 1783, might have been caused by volcanic activity in Iceland. And there it was left - until 1920 when climatologist William Humphreys discovered Franklin’s article.
It was unsurprising that this particular eruption caught Franklin’s attention. The Iceland event had been monstrous. One hundred and thirty five new fissures as well as several craters near the town of Klaustur had opened on June 8 and began erupting, eventually covering 965 sq mi of land and forming a new chain of volcanoes. Reports from around the world, included disastrous flooding, droughts, and anomalously cold temperatures. The intensely hot summer of 1783 in Europe, followed by extreme winters resulted in widespread famine and disease. These harsh conditions, which continued for several years, may have been one of the triggers for the 1789 French Revolution.
The consequences of the 1783 eruption were as globally devastating and the conditions so similar to the 1816 event, that Humphreys correctly surmised that Franklin was on to something and that volcanic activity could alter the climate. Humphreys also looked at data from the August 1883 explosive eruption of Krakatoa and while the aftermath of Krakatoa was less severe than that of Tambora, it was easier to verify that the astonishing sunsets, strange atmospheric displays and reduction in sunlight was a result of the eruption. Better instruments, widely distributed observing stations and global communications played a greater part in allowing scientists to connect the dots. Undersea cables, the proliferation of telegraph facilities and more efficient communication networks meant that people around the world knew of the disaster within hours.
By November of that year, the English poet Gerard Hopkins observed “the glow is intense; that is what strikes everyone; it has prolonged the daylight, and optically changed the season; it bathes the whole sky, it is mistaken for the reflection of a great fire”. By then, everyone knew what was causing the “Krakatoa sunsets”. But because there was still no organized repository of global meteorological data, reliable sea surface temperature measurements, or consistent measurements of atmospheric conditions over the oceans, the resultant cooling of the atmosphere was still poorly documented in the small datasets available.
Around the same time that William Humphreys was investigating past eruptions and their connection to cold periods, the 1912 eruption of the giant stratovolcano, Mt. Katmai, on the Alaskan Peninsula produced the most voluminous amount of ejecta of the 20th century. It also prompted Charles Abbott and his colleague F. E. Fowle to investigate the possible connection between volcanic activity and climate aberrations. Not that they had really wanted to but it was a matter of necessity. Abbott’s 1913 National Geographic article, “Do Volcanic Explosions Affect our Climate?”, describes how, as they were conducting research on the amount of solar energy striking the earth, the two men began to notice something strange in the atmosphere. “Streaks resembling smoke lying along the horizon”, Abbott wrote, appeared and began moving into their observation areas and affecting their measurements. The phenomenon became more noticeable, increasing as time went on. Two more days passed and they began to see “peculiar mottled figures, like those of a mackerel sky”.
Fowle was at Mount Wilson observatory in California and Abbott was near Bassour, Algeria. After days of unrelenting haze, the Algerian expedition finally concluded as did the project at Mount Wilson. When the two men regrouped, they quickly realized that while they had been worlds away from each other, they had been thwarted by the same phenomenon: volcanic ash. The focus of their research quickly changed and after specifically targeting their observations, they arrived at the same conclusion as Franklin and Humphreys. Volcanic ash could indeed reduce the amount of solar radiation striking the earth’s surface, globally and for an extended period of time.
Like Humphreys and Abbott, Willis Milham also mentions the connection between volcanic eruptions and the extreme weather events that follow in an article published in the December 1924 Monthly Weather Review. Like Humphreys, he examined data from the 1815 eruption of Tambora and its aftermath. His use of excerpts from journals and newspapers of the time illuminated the misconceptions formulated by people in an effort to understand the anomalous departure from average conditions. Careful observations of sunspots and moon phases were noted in reference to summer frosts and snow falls. These fancies were much like the amusing assumptions made in 1783 that attempted to correlate the cooling period to the proliferation of Franklin lightning rods that had swept the country. The rods were supposed to have “prevented heat from rising from the earth’s core” into the atmosphere.
But in the end, the conclusions of Humphreys, Abbott, Milham and the rest were considered speculative. The further back in time one goes, the fewer observations there are. The earliest global (and the term ‘global’ is used loosely here) temperature dataset begins in 1850, so drawing a solid hypothesis based on those few data points did not meet rigorous scientific scrutiny. It was also inconvenient that from the 1912 Mt. Katmai eruption until the 1963-64 Mt. Agung event in Bali, there had been no major eruptions from which data could be taken.
Fast forward to today. After several more recent large, devastating eruptions (Mt. St. Helens, Pinatubo and others) and decades of further research, Franklin and the rest have been proven right. Which of course, was not the original point.
My question was: who was the first to connect the dots? And in many ways I found that the answer was both unsurprising and amazing. Amazing that without the bristling array of satellites; ground-based, aerial and orbital electronic observation networks; precision instrumentation; and centuries of advancements, Benjamin Franklin had it right in 1784. Unsurprising coming from a man who said the following:
“Furnished as all Europe now is with Academies of Science, with nice instruments and the spirit of experiment, the progress of human knowledge will be rapid and discoveries made of which we have at present no conception. I begin to be almost sorry I was born so soon, since I cannot have the happiness of knowing what will be known a hundred years hence.”
— Benjamin Franklin
(1) It should be noted that it would not be until the 1980s that research would identify the real culprit for extended atmospheric cooling: sulfate aerosols. Ash falls out of the atmosphere in a few days or weeks but sulfur dioxide, which is ejected into the atmosphere during volcanic eruptions along with ash, combines with water vapor in the stratosphere to form sulfuric acid. Distributed around the planet on high altitude winds, the acid forms sulfate aerosols that are persistent in the atmosphere for months or years, absorbing and trapping solar radiation in the stratosphere which in turns cools the troposphere and the earth’s surface.