This article from The Telegraph provides new evidence on the volcanic climate forcing of the 530's and 540’s. I first ran into the idea that the Plague of Justinian was tied to a volcano-induced climate crisis in William Rosen's book, Justinian's Flea.
The study published in Nature argues for a short period of cooling caused by North American volcanos erupting in 536, followed by an eruption ten-percent larger than the 1815 eruption of Tambora, somewhere in the tropics in 539-540. This would have been similar to the one-two punch of the Great Unknown Eruption of 1809/10 (documented from ice cores as somewhere in the tropics, and about half the size of the Tambora event) followed by the huge eruption of Tambora in 1815. Those led to extreme weather, famine, and epidemics lasting a few years. The evidence is that the 540’s climate event was longer lasting and was followed thirty-five years later by another massive eruption and cooling event.
The Nature article also summarizes evidence for other instances of volcanic forcing back as far as 426 BC. Historians are slowly beginning to weave climate into their understanding, so this kind of research, able to pin these events down to a year or two, and the ability to compare the effects of recent episodes of volcanic climate forcing with the fragments we have in written records, is vital. Every year our understanding get a bit better and the cumulative results are starting to become significant.
