There have long been suggestions of a global event in 1257. Medieval English records speak of 1258 AD as a year without summer, when crop harvests failed due to unseasonable floods and many died. There are accounts of advancing glaciers and paintings from the time showing people skating on frozen Dutch canals and London's River Thames. Medieval records point to a warm weather in the winter of A.D. 1257/1258 in western Europe. In Arras (northern France), for example, the winter was described as so mild “that frost barely lasted for more than two days." (Winter warming of continental regions of the northern hemisphere is recognized as a dynamic response of the atmosphere to high-sulfur eruptions in the tropics.) In the early 1980s a team of Danish researchers ice layers, the Danish researchers found a high amount of sulfuric acid in layers corresponding to the years 1258-1259. Archaeologists recently determined a date for a mass burial of thousands of medieval skeletons in London. It is A.D. 1258. All this is apparently the result of a huge global event, a gigantic volcano eruption that appears to have occurred in Indonesia.
The great volcanic events of the Holocene Period ((the past 12,000 years or so) include the seventh Millennium B.C. Kuril Lake (Kamchatka, Russia), the sixth Millennium B.C. Mount Mazama (Crater Lake, OR), the Minoan eruption of Santorini in the Mediterranean and the Tierra Blanca Joven eruption of Ilopango (El Salvador), possibly in the sixth century A.D.. The 1257 eruption was larger. Estimates of the 1258 stratospheric sulfate load are around eight- times greater than those of Krakatau in 1883 A.D. and twice that of Tambora in 1815 A.D.! The findings of 1258 would make it comparable to the eruption of Taupo in 180 A.D., considered the most intense of known historic eruption.