Medieval Irish chronicles reveal persistent volcanic forcing of severe winter cold events, 431–1649 CE
By Francis Ludlow, Alexander R Stine, Paul Leahy, Enda Murphy, Paul A Mayewski, David Taylor, James Killen, Michael G L Baillie, Mark Hennessy and Gerard Kiely
Environmental Research Letters, Volume 8 Number 2 (2013)
Abstract: Explosive volcanism resulting in stratospheric injection of sulfate aerosol is a major driver of regional to global climatic variability on interannual and longer timescales. However, much of our knowledge of the climatic impact of volcanism derives from the limited number of eruptions that have occurred in the modern period during which meteorological instrumental records are available. We present a uniquely long historical record of severe short-term cold events from Irish chronicles, 431–1649 CE, and test the association between cold event occurrence and explosive volcanism. Thirty eight (79%) of 48 volcanic events identified in the sulfate deposition record of the Greenland Ice Sheet Project 2 ice-core correspond to 37 (54%) of 69 cold events in this 1219 year period. We show this association to be statistically significant at the 99.7% confidence level, revealing both the consistency of response to explosive volcanism for Ireland’s climatically sensitive Northeast Atlantic location and the large proportional contribution of volcanism to historic cold event frequencies here. Our results expose, moreover, the extent to which volcanism has impacted winter-season climate for the region, and can help to further resolve the complex spatial patterns of Northern Hemisphere winter-season cooling versus warming after major eruptions.
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Introduction: Determining the extent to which human activity drives future climatic variation requires knowledge of past climate, allowing us to ascertain the boundaries of natural variability and to test the veracity of models predicting future climate (NRC 2006, Skinner 2008). Developing long palaeoclimatic datasets from multiple sources and regions for the period before the advent of instrumental meteorological recording is therefore critical (Wanner et al 2008, Jones et al 2009). The relationship to climate of natural palaeoclimatic proxies such as tree-rings can, however, be complex and indirect, and is often seasonally specific. In contrast, historical documents can directly register meteorological conditions in all seasons, as well as singular extreme events, at high temporal and spatial resolutions (Pfister et al 1999, 2002, Brázdil et al 2005, 2010). Documentary data can, however, exhibit biases (e.g. where certain weather conditions or extreme events are recorded preferentially to others) and coverage may be intermittent or discontinuous in time (Brázdil et al 2005). Documentary data are, therefore, of greatest value in efforts to improve our understanding of past climatic conditions and the role of climatic forcing factors when combined with data from natural biological and physical proxies. In this study we present a long and novel record of severe short-term cold event occurrence from historical documentary observations in Ireland, 431–1649 CE. We then employ the Greenland Ice Sheet Project 2 (GISP2) ice-core record of atmospheric sulfate deposition as a proxy for past explosive volcanism to investigate the role of volcanic forcing in the incidence of cold events for the Irish region of the Northeast Atlantic.
By Francis Ludlow, Alexander R Stine, Paul Leahy, Enda Murphy, Paul A Mayewski, David Taylor, James Killen, Michael G L Baillie, Mark Hennessy and Gerard Kiely
Environmental Research Letters, Volume 8 Number 2 (2013)
Abstract: Explosive volcanism resulting in stratospheric injection of sulfate aerosol is a major driver of regional to global climatic variability on interannual and longer timescales. However, much of our knowledge of the climatic impact of volcanism derives from the limited number of eruptions that have occurred in the modern period during which meteorological instrumental records are available. We present a uniquely long historical record of severe short-term cold events from Irish chronicles, 431–1649 CE, and test the association between cold event occurrence and explosive volcanism. Thirty eight (79%) of 48 volcanic events identified in the sulfate deposition record of the Greenland Ice Sheet Project 2 ice-core correspond to 37 (54%) of 69 cold events in this 1219 year period. We show this association to be statistically significant at the 99.7% confidence level, revealing both the consistency of response to explosive volcanism for Ireland’s climatically sensitive Northeast Atlantic location and the large proportional contribution of volcanism to historic cold event frequencies here. Our results expose, moreover, the extent to which volcanism has impacted winter-season climate for the region, and can help to further resolve the complex spatial patterns of Northern Hemisphere winter-season cooling versus warming after major eruptions.
Introduction: Determining the extent to which human activity drives future climatic variation requires knowledge of past climate, allowing us to ascertain the boundaries of natural variability and to test the veracity of models predicting future climate (NRC 2006, Skinner 2008). Developing long palaeoclimatic datasets from multiple sources and regions for the period before the advent of instrumental meteorological recording is therefore critical (Wanner et al 2008, Jones et al 2009). The relationship to climate of natural palaeoclimatic proxies such as tree-rings can, however, be complex and indirect, and is often seasonally specific. In contrast, historical documents can directly register meteorological conditions in all seasons, as well as singular extreme events, at high temporal and spatial resolutions (Pfister et al 1999, 2002, Brázdil et al 2005, 2010). Documentary data can, however, exhibit biases (e.g. where certain weather conditions or extreme events are recorded preferentially to others) and coverage may be intermittent or discontinuous in time (Brázdil et al 2005). Documentary data are, therefore, of greatest value in efforts to improve our understanding of past climatic conditions and the role of climatic forcing factors when combined with data from natural biological and physical proxies. In this study we present a long and novel record of severe short-term cold event occurrence from historical documentary observations in Ireland, 431–1649 CE. We then employ the Greenland Ice Sheet Project 2 (GISP2) ice-core record of atmospheric sulfate deposition as a proxy for past explosive volcanism to investigate the role of volcanic forcing in the incidence of cold events for the Irish region of the Northeast Atlantic.
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