The Roman Warm Period and Dark Ages Cold Period
April 30, 2011 4 Comments
UPDATE: In a recent paper, the climate scientist authors refer not to the onset of the Dark Ages Cold Period (c. A.D. 450-950), but to a period of “increased climate variability”. (This variability refers to variations in the hydroclimatic cycle.) The BBC uses the term “climate instability”, which is an amusing term because, of course, the climate is inherently unstable and largely unpredictable. There have been warm periods and cold periods, as well as prolonged droughts and flooding rains, throughout history, and they have been outside of our control or influence.
The paper’s abstract insists that the recent global warming (assuming they mean since the industrial era c. A.D. 1760) is unprecedented, despite acknowledging that past extremes of drought and flood have exceeded anything in the present. So, this begs the question, how can a modern warm period be so unprecedented when it is supposed to increase these types of events which are not occurring. By acknowledging these extremes, they have to acknowledge the stated current warm period may not be so unusual after all. Typically, their abstract ends with the obligatory statement urging action to mitigate the current “unprecedented” warming, thereby ensuring continuance of research funding, furthering such speculations.
[I’ve fixed some of the dead-links and clarified my closing comments.]
“Wet and warm summers occurred during periods of Roman and medieval prosperity. Increased climate variability from 250-600 AD coincided with the demise of the western Roman empire and the turmoil of the migration period,” the team reported.
“Distinct drying in the 3rd Century paralleled a period of serious crisis in the western Roman empire marked by barbarian invasion, political turmoil and economic dislocation in several provinces of Gaul.”
‘Roman rise and fall ‘recorded in trees’ ‘
There have been many periods of greater or equal warming during the Holocene, including most recently the Medieval and Roman Warm Periods:
-Sub-Atlantic Cold Period c. BC 975-250
-Roman Warm Period c. BC 250–AD 450
-Dark Ages Cold Period c. AD 450–950
-Medieval Warm Period c. AD 950–1400
-Little Ice Age c. AD 1400–1850
-Current Warm Period c. AD 1850-?
[Note: The initial warming of 1850-1900 was followed by perhaps an additional overall 0.8 degrees Celsius of warming during the twentieth century.]
‘Roman Warm Period (Europe — Mediterranean) — Summary’
ABSTRACT (capitals my emphasis):
“Climate variations have influenced the agricultural productivity, health risk, and conflict level of preindustrial societies. Discrimination between environmental and anthropogenic impacts on past civilizations, however, remains difficult because of the paucity of high-resolution palaeoclimatic evidence. Here, we present tree ring–based reconstructions of Central European summer precipitation and temperature variability over the past 2500 years. RECENT WARMING IS UNPRECEDENTED, BUT MODERN HYDROCLIMATIC VARIATIONS MAY HAVE AT TIMES BEEN EXCEEDED IN MAGNITUDE AND DURATION. Wet and warm summers occurred during periods of Roman and medieval prosperity. Increased climate variability from ~AD 250 to 600 coincided with the demise of the Western Roman Empire and the turmoil of the Migration Period. Historical circumstances may challenge recent political and fiscal reluctance to mitigate projected climate change.”
‘2500 Years of European Climate Variability and Human Susceptibility’
‘New technique shows Roman Warm Period Warmer than Present Day’
‘Archaeological Finds in Retreating Swiss Glacier’
15 January, 2011