Our eighth A&S Research Paper comes to us from Sir Michael of York of the Barony of Carolingia. He examines a catastrophic climatological event with both modern and historical records, and in the telling introduces us to a very interesting chronicler. (Prospective future contributors, please check out our original Call for Papers.)
Matthew Paris and the VolcanoIn the middle of the 13th century, a massive volcanic eruption occurred in Indonesia. The effects of this eruption changed the weather around the world for years. Modern climate research combined with recent archeological evidence and the medieval chronicles of Matthew Paris paint a haunting picture of a world-wide disaster that has no parallel for the previous several thousand years.
In the fall of 2013 (A.S. XLVIII) the scientific world was all aflutter—a new science paper announced that the location of “the famous 1258 volcano” had been determined. First identified in the 1980’s via ice-core and tree-ring data—the location of the 1258 volcanic eruption had been a decades-long puzzle for geologists. This new research showed location of the eruption (Lombok, Indonesia) and documented that it had been one of the largest of its kind, ejecting huge amounts of volcanic dust and gases high into the stratosphere.
My SCA persona is 13th century English, and when I heard this announcement my first question was “what famous 1258 volcanic eruption”? I’d heard of Krakatoa (1883) and Mount Vesuvius (A.D. 79), but I’d never heard of any other large volcanic eruptions. As a child, I had walked across a volcano in Hawaii and had read about and seen television reports of more modern dramatic eruptions (Mount St Helens 1980, Mount Pinatubo 1991, and Eyjafjallajökull 2010), but apparently, this “famous 1258 volcanic eruption” was something much different.
At the time, for other reasons, I happened to be reading excerpts from a 13th century chronicler’s works. The Illustrated Chronicles of Matthew Paris: Observations of Thirteenth-Century Life had been loaned to me by a friend. In perusing it, I had learned that Matthew Paris was a garrulous monk with lots of opinions, observations and commentary about both the natural world and about every aspect of religious and royal politics. I’d noticed his descriptions of weather, strange events in the sea, eclipses and weird cloud formations alongside all of his various observations about political events, and rants on church and state policies. His Chronicles cover the time from 1235 until his death in 1259.
After hearing about this new volcano—I ran to see what Matthew had to say. I was disappointed to find that this specific book only covered his writings to the year 1250. It took a while to get his complete works—but in the process, I found lots of other news about that specific volcanic eruption: climate data analysis, cemetery burial data, descriptions of how much it changed the global environment et cetera. Within days, I had the whole tale. It’s an amazing story.
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The volcano itself (named “Mount Samalas” by the research team that identified it) is located on the island of Lombok in the Indonesian chain of islands. This island is 770 miles (1240KM) and a couple of islands east of Krakatoa. Today all that is left is a caldera lake with a small cinder cone in the center—the entire mountain having been blasted away by the eruption.
Like Mount Vesuvius and some other violent eruptions, this eruption was a “Plinian” eruption. The name comes from a description written by the Younger Pliny in A.D. 79. He compared the plume of ash and gasses from Mount Vesuvius to the shape of a “stone pine tree“—a narrow rising trunk with an umbrella-top splaying out immediately. This is the most explosive of the volcanic eruption types and can be responsible for global weather effects. The column of ash from these kinds of eruptions can rise all the way to the stratosphere—over 40 KM above the earth’s surface and then be spread around the globe. This NASA article highlights the effects of the much smaller Mount Pinatubo eruption (1991) as documented by the SAGE II satellite (even though the article is actually about the SAGE III new effort). According to this report, “The aerosols in the tropics increased by almost a factor of 100 immediately following the eruption. … had spread into the Earth’s mid-latitudes three months later. … slowly decreased in the atmosphere over several years.”
The effects were immediate and lasted years – and this was for a small eruption. The Mt Samalas eruption was much larger—with much more rock-turned-ash vaulted into the stratosphere.
The Mt Samalas eruption was first detected by examination of ice-cores and tree-ring data during the 1980’s. In various samples, the effects of the eruption were very clearly visible. Ice cores capture dust and ash that falls and is buried by subsequent snowfall. Trees that have a low-growth year have narrow rings in the core of the tree for those years.
The team that determined the location of this volcanic eruption (Dr. Lavigne et al) was able to compare the chemicals in the ice-core deposits to the ash deposits found on Lombok. The samples matched both in composition and date. Their report states that the eruption occurred in the summer of 1257 and that it ejected the most ash and sulfates into the atmosphere of any other volcano in the last 7000 years. Some parts of the island of Lombok are covered by 35 meters of ash—showing that the eruption was huge. Pictures included in their report are astonishing—the ash-fall is clearly visible at the coast where the ocean has eroded the shore.
Their report also mentions that there is evidence (from Indonesian records) of an entire Kingdom buried under all of that ash (like Pompeii). What is most interesting is that they can deduce the time of year of the eruption due to the way the ash from the eruption is spread on the island itself and surrounding areas: the trade winds blow from the east to the west in the summer, and the deposits of ash are much greater to the west of the volcano itself.
It is well understood that the ice-core data provides atmospheric composition changes, and that tree-ring data shows environment changes that affect plant growth. Modern evidence from modern volcanic eruptions (e.g., Mt. Saint Helens, Mt. Pinatubo) demonstrates that lower world-wide temperatures occur when such Plinian eruptions occur. The blocking of sunlight caused by the ash and chemicals inserted into the atmosphere reduces the strength of the sun’s warming radiation. By comparing the ice-core data and the tree-ring data from modern (well recorded events), scientists can extrapolate and estimate the world-wide temperature of the Earth for historic events. The data shows that 1258 and the period just afterwards were substantially colder than usual on a global scale. Both sets of data (tree-ring, ice-core) show that the world-wide temperature was reduced between 0.75 and 2.5 degrees Celsius depending on how you read the data and which prediction model you use. (For those of you that are in America, this is 1.0 to 4.5 degrees Fahrenheit.)
What is most interesting is that further study shows localized weather effects that are contrary to global averages. For instance, this study shows that Plinian eruptions, when they occur in the tropics, make Northern Europe warmer in winter and cooler only in the summer. Another study shows that when this happens, the weather in Northern Europe is wetter and the Southern European climate is drier. This is due to changes in the heating of the Atlantic Ocean and the resulting effects on weather patterns caused by the atmospheric pollution. Look up the term “North-Atlantic Oscillation (NAO)” for more information.
What this means is that different parts of the world get vastly different effects from the injected ash and sulfates from the eruption. Northern Europe gets hammered with weird weather – wetter warmer winters, colder wetter summers. Southern Europe gets drier than average weather with general cooling overall. You can imagine what this does to the farming industry which depends on specific “wet periods” and “dry periods” and specific temperatures.
In my searches for information about this volcano, I ran across stories about an archeological site that was linked with the “famous 1258 volcano”. The links pointed to burial data from a 1991-2007 archeological dig done in London by the London Museum of Archeology at the site of the SpitalFields Market. Their research demonstrates that in the middle of the 13th century, decades before the Black Death (1340’s) there was a period of mass-burial sites in one cemetery in London belonging to St Mary Spital, an Augustine Priory and hospital just north of the Tower of London. According to the report, the priory was in active use from the 1100’s through 1539 AD. Although the data is not precisely datable, it is clear that in the late 1250’s and early 1260’s there was a period where some burial pits had as many as 20 sets of remains—a very unusual pattern, as normally, burials were singular or perhaps two remains in one site. In addition, the research shows that the likely cause of the deaths was not violence. This suggests that famine or diseases are the major causes of death in this era. The images that are available are haunting.
One data point from the burial site suggests that as many as 4000 bodies were recovered from this short period (late 1250’s, early 1260’s) for this one hospital – mostly in mass burial graves. There were other priory hospitals in other parts of England at the time, and several in London alone. If the burial data for any of those other active 13th century hospitals shows the same pattern, we can deduce that something was very wrong.
So—today we know that there were immediate world-wide effects of the volcanic eruption that occurred during the summer of 1257, and that the effects changed the weather, blocked the sunlight and covered the globe with a volcanic haze in the atmosphere. We see burial data suggesting massive deaths, as well as plant evidence (tree-rings) showing reduced growing seasons and cooling.
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What can we learn about what happened in the Middle Ages? How did all of this effect their lives and events in their times? What happened and what can we see?
Matthew of Paris only lives till 1259, but his words describe this event very clearly from what happens to his world. He doesn’t have the slightest idea that there’s this volcano half-a-world away. He just writes what he can see – and with this new view from scientific research, we can understand what he says all too well.
What follows here is a brief set of quotes from his Chronica Majora that illustrate what he saw at the time. Matthew of Paris’ writings are sometimes confusing because he apparently had a practice of taking notes and then entering them into his chronicles at some later time. There are some sections where events that happen months apart are put together in one sentence or two simultaneous sentences. This makes finely-detailed chronology hard to understand from his writings. Sometimes dates appear incorrect—and it appears that he exaggerates—although, now that I have read the science literature, I believe that he was not exaggerating when he wrote these entries.
One other note concerning chronology! Matthew’s “year” runs from the end of October through to the end of October because he uses Royal Year dates—Henry III was first crowned King on October 28th in 1216. But oddly, Matthew uses the following year—so the year 1257 starts in October of 1256. There is a confusing aspect to the seasons as well since the calendar is 10 days off from our calendar (they were using the Julian Calendar, not the newer 18th-century Gregorian Calendar). Matthew also appears to use the planting cycle for his seasons. “Winter” is the end of September through Christmas. “Spring” is January through March.
Read on to see it in his own words. I’ve added personal notes in italics to illuminate essential points. The text is that of the Reverend James Giles’ 1883 translation.
1253 – This year throughout was abundant in corn and fruit; so much so that the price of a measure of corn fell to thirty pence.
Things are going well.
1254 – This year throughout was abundantly productive in fruit and corn, so that the price of a measure of corn fell to two shillings; and like proportion oats, and all other kinds of corn and pulse fell in price to the benefit of the poor plebeians.
Lots of good produce.
1255 – [This year] was throughout so productive in corn and fruit, that a measure of wheat fell in price to two shillings and the same quantity of oats to twelvepence.
Note the prices—two shillings for a measure of wheat and 12 pence for a measure of oats.
1256 … (on 10 Aug), an extraordinary storm, or succession of storms of wind and rain, accompanied by hail, thunder, and lightning, alarmed men’s heads, and caused irreparable damage. One might see the wheels of mills torn from their axles and carried by the violence of the wind to great distances, destroying in their course the neighbouring houses; and what the water did to the water-mills, the wind did not fail to do to the wind-mills. Piles of bridges, stacks of hay, the huts of fisherman with their nets and poles, and even children in their cradles, were suddenly carried away, so that the deluge of Deucalion seemed to be renewed. Not to mention other places, Bedford, which is watered by the Ouse, suffered incomputable damages, as it had done a few years before. Indeed, in one place, six houses immediately adjoining each other were carried away by the rapidity of the torrents, their inhabitants having much difficulty in saving themselves; and other places contiguous to that river were exposed to similar perils.
This is a major event—he described it using a reference to “Deucalion”, the son of Prometheus, who survived a flood brought by Zeus by building a chest with his father and staying afloat till the storm passed.
1256 – Then closed this year, which had been tolerably productive of fruit and corn. … It was beyond measure stormy and rainy, so that, indeed, the times of Deucalion seemed to be renewed. From the day of the Assumption of the Blessed Virgin (Aug 15) to the anniversary of her Purification (Feb 2), the rain ceased not to fall daily in deluges, which rendered the roads impassable and the fields barren. Hence at the end of autumn, the corn was rotted in the ear.
Note that there was good produce, but the summer corn crop was lost to the rain. Note also that the dates here are confusing. If the rain starts in August 1256, then it has to continue till February 1257. This demonstrates that his entries are made long after the fact.
1257 – Of the extraordinary fall of rain, and the thunder during the winter. On the Innocents’ Day in this year such a quantity of rain fell that it covered the surface of the ground, and the times of Deucalion seemed to be renewed. The furrows looked like caves or rivers, and the rivers covered the meadows and all the neighbouring country, so that it presented the appearance of a sea. That from one case other similar ones may be understood, I may mention, that one river alone in the northern parts of England carried away seven large bridges of wood and stone, the mills, too, and the neighbouring houses, were carried away by the violence of the torrent-swollen streams and destroyed.
There are two possible interpretations of “Innocents Day”. One is the end of December – where the “Innocents” are the children. It is also the case that July 28 is “St. Innocent’s Day” (St Innocent was a Pope). This latter choice matches the likely eruption date for the volcano (summer).
On the aforesaid day, too, a fierce whirlwind, accompanied by a violent hail-storm, disturbed the atmosphere and obscured the sky with darkness like that of night. The clouds collected together, and from them the lightning darted forth with fearful vividness, followed by claps of thunder. This thunder was clearly a bad omen, for it was mid-winter, and the cold was equal to that generally felt in February. This weather was followed by sickly unseasonable weather, which lasted about three months.
This is a sudden onslaught of cold weather and fierce storms. The word “midwinter” suggests that this was in the late October or early November time frame. (“Winter” is late September through the end of December). The date very confusing because he just said 28-Dec (Innocent’s Day) which is at the end of “winter” but in an earlier note he says the rain started in mid August. My conclusion is that it rained pretty much all the time with lots of stormy weather. If the volcano erupted in the summer – it would take a month or three for the volcanic emissions to get to the northern latitudes, so this fits with the scientific evidence we have.
1257—The Summary of the Year—This year was throughout barren and meagre; for whatever had been sown in winter had budded in spring, and grown ripe in summer, was stifled and destroyed by the autumnal inundations. The scarcity of money, brought on by the spoilation practiced by the king and the pope in England brought unusual poverty. The land lay uncultivated, and great numbers of people died from starvation. About Christmas, the price of a measure of wheat rose to ten shillings. Apples were scarce, pears more so, figs, beechnuts, cherries, plums—in short, all fruits which are preserved in jars were completely spoiled.
Note the price of wheat—ten shillings. Note that fruit and other crops were destroyed by the autumnal rains—this is two years in a row (1256 and 1257) where there was rain that damages the crops in the fall.
…This pestiferous year, moreover, gave rise to mortal fevers, which raged to such an extent that, not to mention other cases, at St Edmund’s alone, more than two thousand dead bodies were placed in the large cemetery during the summer, the largest portion of them during the dog-days. There were old men, who had formerly seen a measure of wheat sold for a mark, and even twenty shillings without the people being starved to death. … This year too generated chronic complaints, which scarcely allowed free power of breathing to anyone labouring under them. Not a single fine or frosty day occurred, nor was the surface of the lakes at all hardened by the frost as was usual; neither did icicles hang from the ledges of houses; but uninterrupted heavy falls of rain and mist obscured the sky until the Purification of the Blessed Virgin Mary.
This reference to mortal fevers clearly indicates disease (e.g., dysentery, influenza). He mentions a large numbers of deaths. The chronic complaints about breathing suggest air pollution from the volcanic ash, or perhaps mold from the damp weather. The weather is off—The Feast of the Purification is in early February, so this winter is warm.
1258 – Of the arrival in England of some ships laden with wheat. At this same time, too, whilst an extraordinary famine was prevailing to such a degree that numbers pined away in themselves and died, a measure of corn being sold at London for nine shillings or more, about fifty large ships arrived there from the continent, having been sent by Richard, king of Germany, laden with corn, wheat, and bread. … It was stated as positive fact, that any three counties of England united had not produced so much corn as was brought by these vessels.
Richard, the King of Germany is Henry III’s son. Notice the price of corn. Notice the complete loss of crops.
1258—Of the remarkable nature of the season. In this same year, the calm temperature of autumn lasted to the end of January, so that the surface of the water was not frozen in any place during that time. But from about that time, that is to say, from the Purification of the Blessed Virgin till the end of March, the north wind blew without intermission, a continued frost prevailed, accompanied by snow and such unendurable cold, that it bound up the face of the earth, sorely afflicted the poor, suspended all cultivation, and killed the young of the cattle to such an extent that it seemed as if a general plague was raging amongst the sheep and lambs.
The winter started mild and then turned bitter cold in the spring.
1258—Of the great famine which prevailed throughout the whole of England. About the feast of the Trinity (May 19) in this year, an awful and intolerable pestilence attacked the people, especially those of the lower orders, and spread death among them in a most lamentable degree. In the city of London, fifteen thousand of the poor had already perished. … In fact famine prevailed in England to such great extent, that many thousand human beings died of hunger; for the crops only arrived at maturity so late in the autumn, in consequence of the heavy rains, that the harvest was only got in by All Saints’ day in several parts of the kingdom, and a measure of corn was sold for sixteen shillings.
There are no crops and this causes disease and death. Notice that 15,000 die in London which at the time had a population of about 45,000 to 50,000. Notice the price of corn.
1258—Of the mortality caused by the famine amongst the people. About the same time, such great famine and mortality prevailed in the country, that a measure of wheat rose in price to fifteen shillings and more, … and numberless dead bodies were lying about the streets. … Unless corn had been brought for sale from the continent, the rich would scarcely have been able to escape death. … the dead lay about, swollen up and there was scarcely any one to bury them; nor did the citizens dare or choose to receive the dead into their houses, for fear of contagion. … if corn could have been sold for a small price per measure, scarcely any one could have been found with the means of buying it.
Notice the price of wheat. The bodies accumulate too fast for normal burial—hence mass burials are likely.
… At this time, too, that is, at the end of July and beginning of August, … such misery, want and famine prevailed, that those who usually aided others were now amongst the unfortunates who perished from want. What alarmed the lower orders more than the nobles, was the continued heavy falls of rain, which threatened destruction to the rich crops which God had given hopes of previously. To sum up briefly, England would have failed in herself, had she not been restored to life by the arrival of some vessels, belonging to traders on the continent, which were laden with corn and bread for sale, brought from Germany and Holland; still many who spent all their money, died of hunger and want.
Even the people who help others are now perishing. Without food imports, there was no chance. Notice it is still raining.
At the feast of the Assumption of the Blessed Virgin (Aug 15), when generally the barns are filled with the yearly crops of corn, scarcely even a shingle sheaf was ripe; and as the rain increased daily, the hired labourers and their cattle caused a great expense daily, without being able to leave their houses or to do any good in the fields. In consequence, a circumstance hitherto unknown, at the feast of All Saints, the corn was standing about the country ready to be cut down, but useless and spoiled almost. In some places, indeed, although late and the crop of little use, it was cut and carried, whilst in many others it was left altogether in the fields to be used as manure to enrich the soil. It should be known also, that in that year the land produced such an abundant crop, that, had it all been saved, it would have been sufficient for nearly two years’ consumption.
The rain ruins the crops despite wonderful promise (lots of crops—just all spoiled).
1258—Of the general disposition of events during the whole year. This year throughout was very dissimilar to all previous ones, bringing disease and death, and heavy storms of wind and rain. Although in the summer-time a fair promise of abundant crops of corn and fruit was given, yet in the autumn the continual heavy rains spoiled the corn, fruit and all kinds of pulse; and at the Advent of our Lord, in some parts of England, as above stated, the barns remained empty, and the crops remained ready to be cut, but entirely spoiled: for as the corn shot up, the ear and the straw rotted together, and as men died from the want of corn, so the cattle died from the want of fodder; and though England was drained of money on many pretexts, yet the people were obliged, at the instigation of hunger, to pay sixteen shillings for a measure of corn, whilst still moist and shooting; and consequently the poor pined away with hunger, and died.
The yearly summary includes a political stab at the King (England being drained by him of money on many pretexts). The poor don’t have warehouses filled with grain and can’t buy grain—so they perish.
…The dying staggered away into different by-places to yield their last wretched breath; and of these there was such a great number, that the gravediggers were overcome with weariness and threw several bodies into one grave. The people of the middle class, seeing their food failing them, sold their flocks, diminished the number of their household, and left their land uncultivated, whereby all hope of rising from this abyss, which hope generally consoles those despairing, was entirely extinguished. Had not corn been brought for sale from the continent, there is no doubt but England would have perished in herself.
Proof that mass-burials became necessary. A repetition of the import of food from the mainland shows how much worse the UK was affected by this weather.
In the same [year], when the sun was in Cancer (late June thru July), an unexpected pestilence and mortality fell upon mankind; and to say nothing of the great numbers that died in other places, in Paris alone, more than a thousand human beings were consigned to the tomb. Oil, wine, and corn also were spoiled. As the two-handed sword of death, which spares no-one, strikes sometimes one and sometimes another, and hurries from the world the rich and the poor alike, so Fulk, bishop of London, died during that deadly pestilence…
This looks like a repetition of the previous entries except for the mention of Paris. Oil and wine don’t keep long—so what reserves would be spoiled due to age. Bishop Fulk was very-well regarded.
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Matthew Paris died in 1259, probably from old-age – he was nearly 60. It’s also possible that the depredations of the time made survival harder and that he was one of the fatalities from the agricultural and environmental changes wrought by the volcanic eruption. So far, I’ve found no other written records on the mainland or other parts of England that are as detailed as Matthew’s work.
The astute reader will notice that the nasty weather starts almost exactly one year before the volcano erupts and the descriptions sound just like the global cooling effects of the weather one expects from the volcanic eruption. Combined with Matthew’s repeated phrases (e.g., references to the Deucalion and specific dates) one wonders whether there are errors in Matthew’s chronicle (he was getting old) – or translation errors or perhaps errors in the scientific literature.
However, if you read Matthew’s Chronicles, you will find lots of repeated stock phrases and milestone dates. (For instance, he seems to favor dates associated with the Blessed Virgin Mary). In addition, as noted above, Matthew is noted for poor chronology because he makes notes which are put into the Chronicle long after the events occurred. I’ve been able to validate some of his dates from other sources so I’m fairly sure that many are accurate. Given what we know now, the only real conclusion one can draw is that England got a double-whammy of an uncharacteristically bad year followed by the volcanic winter. This makes the events described here all the more tragic.
If you want to know more about the amazing stories of Matthew of Paris, you can find copies of his work in Latin (Henry Richard Luard made the canonical transliteration), or in English (Reverend James Allen Giles made the canonical English translation), or look up the works of Professor Richard Vaughan, a modern historian who wrote several works about Matthew. Look also for Susan Lewis’ work on Matthew’s art.
Matthew’s work is an inspiration for me. His writings contain countless little snippets that become stories for the campfire or other venues. His opinions enlighten our understanding of how that world worked and provide a rare insight into that period. His tales of plots, political shenanigans and the movements of the major actors in that period show us a vital, dynamic, widely aware population of smart people. Almost every page of his Chronica can be used as a starting point for yet another story or search for understanding.
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If you want another story like this one, look for a book published in 2014 by Gillen D’Arcy Wood (see citations below). The author chronicles an equivalent world-wide volcanic disaster that takes place in 1815 on the Indonesian island of Sumbawa right next to Lombok. The volcano (named Tambora) produced an eruption that was about half the size of the Mt. Samalas eruption. According to the author’s research, that eruption is responsible for many well-known social memories (“the year without a summer”, Frankenstein, Dracula). As I was discovering Matthew of Paris and his story about Mt. Samalas, this story about Tambora was published. The descriptions of events in this book are as chilling as Matthew’s story. It reinforced my belief that indeed, what Matthew reports is very accurate.
Connell, B., A. G. Jones, R. Redfern & D. Walker (2012), A bioarchaeological study of medieval burials on the site of St Mary Spital: excavations at Spitalfields Market, London E1, 1991–2007, MOLA 2012. ISBN 978-1-907586-11-8
D’Arcy, Gillen, (2015), Tambora: The Eruption That Changed the World, Princeton University Press , Princeton, NJ.
Fischer, E. M., J. Luterbacher, E. Zorita, S. F. B. Tett, C. Casty, and H. Wanner (2007), European climate response to tropical volcanic eruptions over the last half millennium, Geophysical Research Letters, 34, L05707, doi:10.1029/2006GL027992.
Giles, J.A. (trans.), Matthew Paris’s English History from the year 1235 to 1273. H.G. Bohn, London, 1853, Three Volumes (multiple editions available from various publishers).
Lavigne, F., J. Degeai, J. Komorowski, S. Guillet, V. Robert, P. Lahitte, C. Oppenheimer. M. Stoffel, C. M. Vidal, Surono, I. Pratomo, P. Wassmer, Irka Hajdas, D. S. Hadmoko & E. de Belizal (2013) Source of the great A.D. 1257 mystery eruption unveiled, Samalas volcano, Rinjani Volcanic Complex, Indonesia, Proceedings of the National Academy of Sciences, 110: 16742–16747, doi: 10.1073/pnas.1307520110 .
Mann, M., J. D. Fuentes, S. Rutherford, Underestimation of volcanic cooling in tree-ring-based reconstructions of hemispheric temperatures (2012), Nature Geoscience 5, 202–205 (2012), 2012. doi: 10.1038/ngeo1394 (See image: http://www.nature.com/ngeo/journal/v5/n3/fig_tab/ngeo1394_F1.html)
NASA Sage III, Verified March 2016 http://earthobservatory.nasa.gov/Features/SAGEIII/SAGEIII_2.php
Oppenheimer, C. (2003), Ice core and palaeoclimatic evidence for the timing and nature of the great mid-13th century volcanic eruption. International Journal of Climatology, 23: 417–426. doi: 10.1002/joc.891
Pauling, A., J. Luterbacher, C. Casty & H. Wanner (2006), Five hundred years of gridded high-resolution precipitation reconstructions over Europe and the connection to large-scale circulation, Climate Dynamics 26: 387–405, doi: 10.1007/s00382-005-0090-8
Timmreck, C., S. J. Lorenz, T. J. Crowley, S. Kinne, T. J. Raddatz, M. A. Thomas, and J. H. Jungclaus (2009), Limited temperature response to the very large AD 1258 volcanic eruption, Geophysical Research Letters, 36, L21708, doi:10.1029/2009GL040083.
Vaughan, Richard, (trans.), (1993), The Illustrated Chronicles of Matthew Paris: Observations of Thirteenth-Century Life, Alan Sutton Publishing, Gloucestershire, UK.