Did American volcanoes trigger fall of Roman Empire?

Volcanoes triggered a huge dust cloud which blocked out the Sun for 18 months in the 6th century

The study shows that 15 of the 16 coldest summers recorded between 500 BC and 1,000 AD followed large volcanic eruptions - with four of the coldest occurring shortly after the largest volcanic events found in record.

The new reconstructions is derived from more than 20 individual ice cores extracted from ice sheets in Greenland and Antarctica and analysed for volcanic sulphate.

"Ice-core timescales had been misdated previously by five to ten years during the first millennium leading to inconsistencies in the proposed timing of volcanic eruptions relative to written documentary and tree-ring evidence recording the climatic responses to the same eruptions," said Dr Francis Ludlow, of the Yale Climate & Energy Institute.

Together with Dr Conor Kostick from the University of Nottingham, Ludlow translated and interpreted ancient and medieval documentary records from China, Iraq and Europe that described unusual atmospheric observations as early as 254 years before Common Era (BCE).

These phenomena included diminished sunlight, discoloration of the Sun the presence of solar haloes, and deeply red twilight skies.

The research was published in the journal Nature.

http://www.telegraph.co.uk/news/science/science-news/11726459/Did-American-volcanoes-trigger-fall-of-Roman-Empire.html