Volcanoes and the Beginning of the Little Ice Age

This article was prompted by a comment to my October 2013 article on the 1258 (now believed to be 1257) A.D. Rinjani, Indonesia, volcanic eruption. Robert Nason noted a Zuni myth that supported a link between the Rinjani explosion and the decline of the Anasazi in the American Southwest. 

The Rinjani blast was likely twice as large as the 1815 Mt. Tambora blast, and apparently marks the beginning of the Little Ice Age. More accurate dating places the eruption as actually occurring between May and October of 1257. According to the National Geographic article just cited, "[t]he cataclysm blasted 10 cubic miles (40 cubic kilometers) of debris up to 27 miles (43 kilometers) high into the sky, producing fallout that settled around the world." Moreover:

Though the eruption was equatorial, its impact was felt and noted around the world. "The climate was disturbed for at least two years after the eruption," Lavigne said. Evidence of this was found in studies of tree rings that revealed abnormal growth rates, climate models, and historical records from as far afield as Europe."

Medieval chronicles, for example, describe the summer of 1258 as unseasonably cold, with poor harvests and incessant rains that triggered destructive floods—a "year without a summer." The winter immediately following the eruption was warmer in western Europe, however, as would be expected from high-sulfur eruptions in the tropics. The team cites historical records from Arras (northern France) that speak of a winter so mild "that frost barely lasted for more than two days," and even in January 1258 "violets could be observed, and strawberries and apple trees were in blossom."

Prior to the location of the eruption being pinpointed, Richard B. Stothers penned a paper discussing the impact of the 1257 explosion. (See "Climatic and Demographic Consequences of the Massive Volcanic Eruption of 1258," Climatic Change 45: 361–374, 2000). From his abstract:

Somewhere in the tropics, a volcano exploded violently during the year 1258, producing
a massive stratospheric aerosol veil that eventually blanketed the globe. Arctic and Antarctic ice cores suggest that this was the world’s largest volcanic eruption of the past millennium. According to contemporary chronicles, the stratospheric dry fog possibly manifested itself in Europe as a persistently cloudy aspect of the sky and also through an apparently total darkening of the eclipsed Moon. Based on a sudden temperature drop for several months in England, the eruption’s initiation date can be inferred to have been probably January 1258. The frequent cold and rain that year led to severe crop damage and famine throughout much of Europe. Pestilence repeatedly broke out in 1258 and 1259; it occurred also in the Middle East, reportedly there as plague. Another very cold winter followed in 1260–1261. The troubled period’s wars, famines, pestilences, and  earthquakes appear to have contributed in part to the rise of the European flagellant movement of 1260, one of the most bizarre social phenomena of the Middle Ages. 

Stothers reports that, from the accounts of the time, the initial impact was a "dry fog" that dimmed the sunlight and darkened two eclipses of the moon. This "fog" apparently had disappeared by 1262. Stothers also remarks on the impact on weather. He writes:

[A] long cold spell occurred in England between February and June that year [1258]. The same winter is also reported to have been a severe one at Prague in Bohemia and the springtime was noted as harsh in northern Iceland. 

... After the very rainy autumn of 1258, the following winter in England was unexceptional. Matthew Paris (1259), who regularly reports in detail on the weather near London, indicates nothing unusual for that winter. The Chronicle of Novgorod (1471) mentions an odd frosty day in Russia during April 1259. The summertime afterward was hot and dry in Austria and Germany and hot and stormy in France, while it rained a lot in England. 

Less is known about the weather in the following year, 1260. After a very mild winter, central France experienced severe cold and snow during April. But the summer weather was alternately dry and stormy, with a lot of hail, near Prague and likewise near London. 

It was not until later that year that Europe suffered another very cold winter. The winter of 1260–1261 struck Iceland so severely that people were forced to slaughter many of their livestock (Thórdarson, 1284) and ice formed in the sea all around the island. Very harsh winter conditions are also reported for England and for northwestern Italy. In Alsace, the Ill River froze, but it is not clear whether this happened in the winter of 1260–1261 or of 1261–1262, or in both winters.

(Citations omitted). The weather negatively impacted crops. Stothers indicates:

... The heavy summer and autumn rains in 1257 and 1258 ruined crops throughout England, western Germany, France, and northern Italy. Severe famine is explicitly attested in many localities, and can also be inferred elsewhere from the high prices of staple agricultural commodities. 

England was especially hard hit. Famine in the countryside drove thousands of villagers into London, where many of them perished from hunger. Richard of Cornwall, the king of Germany, was able to ship some grain from Germany and Holland into London to alleviate the distress of the poor who could afford to buy. The price of food throughout England rose, nonetheless, and eventually specie itself became in short supply, having been already depleted by heavy tax exactions at the hands of both the church and state.

(Citations omitted). Apparently, France experienced poor crops and famine as well, while records indicate higher food prices in the Italian states. Finally, contemporary reports record a famine during 1258 in the general region of Iraq, Syria, and southeastern Turkey.

Stothers also writes that the cooler weather contributed to outbreaks of disease. Beyond the expected diseases due to poor or inadequate diet, Stothers observes:

The main scourge of human beings in the period, however, was the great pestilence of April 1259. This epidemic is known to have struck London, other parts of France, Italy, and, probably, Austria. Riccobaldo of Ferrara (1313) also mentions the pestilence, but under the year 1258. The chief symptoms were chilliness and listlessness (frigor) that could linger for several months or else kill rather suddenly. Although an influenza epidemic is a possible explanation, the diagnostic data are too few for us to go beyond this mere speculation. 

In the Middle East, there was also reported a great pestilence in 1258, affecting Iraq, Syria, and southeastern Turkey. It was called ‘plague’by the 14th century Syrian chronicler Ab l-Fid’, and was said to have been especially severe in Damascus; it is also mentioned by the 15th century Egyptian historian al-Maqr z ̄. This pestilence continued until 1260, or perhaps it merely reappeared then, at least in southeastern Turkey. Because the Middle East has been historically prone to epidemics of bubonic plague, possibly that is what it was.

(Citations omitted).

This one volcanic explosion was not solely responsible for creating the Little Ice Age. There were other significant eruptions in the relevant time period. For instance, Stothers mentions that there apparently was a significant eruption about the same time in Mexico. Chaochao Gao, Alan Robock, and Caspar Ammann published a paper in 2008 in  the Journal of Geophysical Research-Atmospheres entitled "Volcanic Forcing of Climate over the Past 1500 Years: An Improved Ice-Core-Based Index for Climate Models," in which they state:

We see that the largest stratospheric sulfate aerosol injection events are the 1259 Unknown [Rinjani], 1453 Kuwae, 1815 Tambora eruptions in tropical regions, and the 1783 Laki eruption at high latitude of the NH [Northern Hemisphere]. The Kuwae sulfate injection was one year later in NH than SH since the peak deposition showed up a year later in Arctic ice cores. We also found a series of moderate to large sulfate injections during the 13th century, in 1228, 1259, 1268, 1275 and 1285 C.E. The cumulative volcanic sulfate flux in the 13th century was two to 10 times larger than that in any other century within the last millennium.

Also in 2008, David P. Schneider, Caspar M. Ammann, Bette L. Otto-Bliesner, and Darrell S. Kaufman published a paper in the Journal of Geophysical Research, entitled "Climate response to large, high-latitude and low-latitude volcanic eruptions in the Community Climate System Model" which correlated four large eruptions in 1257–58, 1269, 1278 and 1286 with the onset of cooling that started the Little Ice Age. Their modeling indicated that large volcanic eruptions in the tropics produce longer lasting climate impact world-wide, including cooler summers and reduced precipitation (up to 20% reduction in some areas). The cooling trend is reinforced by increased sea ice and ice accumulation. 

This article from Science Magazine reports on research by Gifford Miller of the University of Colorado, Boulder, which analyzed ice core samples showing a sudden die off of vegetation on Baffin Island (in the Arctic) between 1275 and 1300. The article notes:

... cooling following even a huge eruption lasts only until the debris falls out of the stratosphere after a few years. 

But Miller and his colleagues did some climate modeling to see what closely spaced eruptions might do to climate. In a climate model that included Arctic sea ice, repeated volcanic cooling sent sea ice southward along the east coast of Greenland. Its melting made surface waters less salty, reducing ocean mixing and thus chilling the waters that return to the Arctic. There the colder water completed a feedback loop by encouraging the formation of more sea ice. In at least some model runs, that feedback loop maintained an icy chill directly upwind of Europe for centuries.

(See also this article from Earth Magazine and this article at Skeptical Science).

Returning to the original comment that prompted this post, the NOAA makes the following observations about the end of the several cultures in the American Southwest:

... "The decline of Chaco apparently coincided with a prolonged drought in the San Juan Basin between 1130 and 1180. Lack of rainfall combined with an overtaxed environment may have led to food shortages. Even the clever irrigation methods of the Chacoans could not overcome prolonged drought. Under these pressures Chaco and the outliers may have experienced a slow social disintegration. The people began to drift away." 

During the 13th Century, the Ancient Pueblo peoples of Mesa Verde and nearby regions also abandonded their masonry homes. For many decades the conventional wisdom was that severe drought pushed them from the region due to crop failures. Paleo proxy data from tree rings and packrat middens have been used as evidence that a severe drought had hit the region. Analysis of bones from the inhabitants which showed malnutrition seemed to confirm the drought theory. 

The more scientists study the situation, the more complex the problem actually becomes. Yes, there was a drought (see the chart above which is based on tree ring data from Northeast New Mexico collected by Henri Grissino-Mayer, 1996), but was it really severe enough to force the Ancient Pueblos from their homes? Some researchers were skeptical. Evidence of cannibalism and human sacrifice was found in the region, adding new questions to the mix. Were the Ancestral Pueblos pushed out of the region by other tribes, such as the Apache and Navajo, or threatened by bands from the central valley of Mexico intent on human sacrifice? (White, 1992). Or did disease, perhaps something akin to the modern day hanta virus that can be triggered by sudden shifts from dry to wet climates, causing increases in disease carrying deer mice populations, run through the communities? (Martin, 1994) 

Other researchers took another look at climate just to make sure they weren't missing something, and Matthew Salzer (2000) noted there was significant volcanic activity, with one particular event-- likely the largest of the Holocene that occurred in 1259 A.D. -- that may have chilled the atmosphere, thereby shortening the growing season and perhaps disrupting normal rainfall patterns.