One of the world’s leading tree ring experts is coming to this year’s Orkney Science Festival to outline evidence for catastrophes in ancient times.
Prof. Mike Baillie of Queen’s University Belfast built up in the 1980s a year-by-year chronology of tree-ring growth reaching 7,400 years into the past. On close examination of the sequence he has found several periods where the tree-ring record showed a severe environmental downturn. The periods were around 2354 BC, 1628 BC, 1159 BC, 208 BC, and AD 540.
The evidence that he has gathered suggests that these downturns were wide-ranging catastrophic events. For instance the AD 540 event is found in tree-ring chronologies from Siberia through Europe and North and South America.
Cores from the Greenland ice cap show a high level of ammonium salts preserved in the ice from this time – the ammonium deposit is a sign of a large-scale decay of trees, carried by the wind, as would result from a forest fire.
The ammonium signal in the Greenland ice for AD 540 is the second highest, with the highest corresponding to a later date, AD 1014.
Seeking a possible explanation, Prof. Baillie noted that at each of these dates, an appearance of a comet was recorded. Further, Chinese archives record fireball activity in the Taurid meteor streams over the period of AD 400-600. Activity of meteors over such a sustained period suggests that they come from cometary debris.
He followed up by searching through every possible ancient record, from annals and histories to mythology and legend. He has found that the various downturns in the tree-ring record are associated with accounts of comets or other signs in the sky, and often with collapses of civilizations or turning points in history.
One example comes from China, where the records of the Shang dynasty speak of severe environmental disturbances at its start and end. In the reign of the last Shang king, for instance, it is recorded that ‘it rained ashes, the rain was grey… it snowed in July.’ The Chinese records also speak of a comet at these times – the very first written records of such a sighting. Prof. Baillie says that the dates seem to fit the tree-ring chronology.
He believes that a number of the stories from myths and legends of catastrophe from the sky are references to actual phenomena. He has built up evidence to suggest that the 1628 BC event in the tree-rings coincides with the biblical Exodus, with its phenomena of dust, days of darkness, the death of fish and livestock, the earth opening, and the ‘pillar of cloud by day and fire by night’.
He says that the 1159 BC event is linked to the biblical account of a catastrophic event during the reign of David, with Psalm 18 describing how ‘earth shook and trembled’ and speaking of fire, darkness, hailstones and coals of fire from the heavens.
Prof. Baillie has also studied source material for the AD 540 environmental downturn, with examples such as Geoffrey of Monmouth’s description of the birth of King Arthur, which was said to have been presaged by the appearance of a ‘Dragon Star’:
Prof. Baillie suggests that this and other stories of dragons from this period, including the tale of Beowulf and references to St Michael fighting the dragon, are a description of the appearance of a comet in the sky and associated phenomena, which for a near-impact could also include electric discharges.
He says that the imagery in the myths and the times between the various environmental downturns are consistent with the suggestion by two British astronomers, Victor Clube and Bill Napier, of a comet with an earth-crossing orbit.
Prof. Baillie’s ideas are of potential interest for various questions from Orkney’s prehistory, for instance the possible downturn in climate in the Bronze Age, and also the decline of the Pictish power in 6th-century Orkney which led to the islands being ruled by a king in Inverness.
He will give three talks in this year’s Orkney International Science Festival. The first, Exodus to Arthur, will be on the opening day, Thursday 6 September. On Monday 10 September he will explain the science of tree rings, and the day after he will look at tree-ring and ice-core data for the period just before the start of the Black Death and open the question of a possible connection.