Identifying volcanic signals in Irish temperature observations since AD 1800

Large volcanic eruptions have been shown to affect temperature patterns to varying degrees on continental, hemispheric or global scales. However, few studies have systematically explored the influence of volcanic eruptions on temperatures at a local, Irish level. The focus of this paper is to determine the impacts of five high-magnitude low-latitude volcanic eruptions and one such Icelandic event on Irish climate over the past �200 years. Daily temperature data from the Armagh Observatory, Co. Armagh, Northern Ireland was used to assess the influence of volcanic eruptions on seasonal and yearly values through time. The paper explores volcanically-induced temperature trends by filtering out the influence of the North Atlantic Oscillation (NAO) and solar variability, and goes on to employ a variation of Superposed Epoch Analysis to identify which seasons and years are most significantly affected by large volcanic eruptions. Armagh temperatures proved particularly responsive in the spring, with a significant decrease in values in the four years following an eruption. Winter temperatures also exhibited a volcanic influence, with a small initial increase in the year of and year following an eruption, and a significant decrease in residual temperature in years two and three after the event

The long-term temperature record from Markree Observatory, County Sligo, from 1842 to 2011

This study analysed long-term temperature patterns in the north-west of Ireland using a previously unexplored data-set from Markree Observatory, County Sligo. The Markree series extends back to 1842, making it one of the longest instrumental temperature records in Ireland and is renowned for holding the lowest recorded temperature for the island of Ireland, 198C on 16 January 1881. Despite its length, this record has been largely absent from past analyses of Ireland’s long-term temperature trends, rendering spatial coverage for the extended Irish climate chronology incomplete. Daily data stored in a variety of the historical archives were gathered and digitised and monthly records created. Calibrations to account for instrumentation, time of reading and exposure were applied where possible in order to standardise the record. Trends were subsequently investigated for seasonal averages of daily minimum, maximum and mean temperatures, and a comparison with previously published long Irish temperature records was carried out to situate the Markree record among the existing long-term series. Although the Markree series follows similar patterns to the other long-term temperature records, it displays more decadal variability, particularly in its minimum values which show a higher rate of late twentieth century warming compared to the other records. Due to its geographic location and surrounding topography shielding the site from direct ocean influences and prevailing south-westerly winds, Markree displays characteristic features of a more inland station (low minimum temperatures and large diurnal ranges) even though it is located only 7 km from the Atlantic Ocean. Such findings highlight the necessity of including the Markree data-set in future Irish climate change research

Identifying volcanic signals in Irish temperature observations since AD 1800

Large volcanic eruptions have been shown to affect temperature patterns to varying degrees on continental, hemispheric or global scales. However, few studies have systematically explored the influence of volcanic eruptions on temperatures at a local, Irish level. The focus of this paper is to determine the impacts of five high-magnitude low-latitude volcanic eruptions and one such Icelandic event on Irish climate over the past 200 years. Daily temperature data from the Armagh Observatory, Co. Armagh, Northern Ireland was used to assess the influence of volcanic eruptions on seasonal and yearly values through time. The paper explores volcanically-induced temperature trends by filtering out the influence of the North Atlantic Oscillation (NAO) and solar variability, and goes on to employ a variation of Superposed Epoch Analysis to identify which seasons and years are most significantly affected by large volcanic eruptions. Armagh temperatures proved particularly responsive in the spring, with a significant decrease in values in the four years following an eruption. Winter temperatures also exhibited a volcanic influence, with a small initial increase in the year of and year following an eruption, and a significant decrease in residual temperature in years two and three after the event

Assessing recent climatic and human influences on chironomid communities from two moderately impacted lakes in western Ireland

This study assessed the influences of climate warming and human impacts on Irish lakes over the late nineteenth to early twenty-first centuries. High-resolution chironomid (Insecta: Diptera) stratigraphies were developed for two low- to mid-elevation lakes in northwest Ireland to determine if lakes with mild-to-moderate human impacts can be used to accurately reconstruct mean July air temperature. Application of an Ireland-based chironomid-inference model to quantitatively estimate July air temperature (r2jack = 0.60, RMSEP = 0.57�C) revealed that chironomids can reflect changes in Irish temperature, particularly post-1980 when warming accelerated, although this signal becomes compromised with intensified human impacts. A biotic response to nutrient enrichment and soil erosion from direct human activities was identified through a comparison of chironomid autecology with known catchment changes. Redundancy analysis and time seriescomparisons were used to identify when faunal turnover is a function of local (nutrient input, erosion) versus extra-regional (climate) drivers over the recent past, and identify any thresholds of human influence within the catchments. This study highlights the importance of careful site selection as moderately impacted sites do not follow a simple scheme, as well as multi-proxy analysis to assess catchment-based human activity for longer term chironomid-based temperature reconstructions in Ireland

Evaluating the dendroclimatological potential of Taxus baccata (yew) in southwest Ireland

Tree-ring research in Ireland has typically been dominated by Quercus species, particularly Quercus petraea and Quercus robur. Recent years have seen a greater focus on multi-species reconstructions in Ireland but, due to difficulties with the hardness of the wood, missing/pinched rings and fused stems, Taxus baccata has not been included in these investigations. Despite these difficulties, a 31-tree, 204-year T. baccata chronology was successfully constructed from Killarney National Park, southwest Ireland. The chronology exhibits promising dendroclimatological potential, with climatic responsiveness equivalent to that of the other major Irish tree taxa, including Quercus. The chronology shows the strongest relationship with May–June precipitation from Muckross House synoptic station (1970–2007; r = 0.521, p < 0.01) and Valentia Observatory (1941–2007; r = 0.545, p < 0.01). November–April temperatures also exhibited a strong relationship with the chronology post-1970 (r = 0.605, p < 0.01 for Muckross House, r = 0.567, p < 0.01 for Valentia Observatory), but this relationship is not time stable and breaks down for the pre-1970 Valentia Observatory record. The long-lived nature of T. baccata, the exceptional preservation of wood and rings in this hard softwood species, as well as its prominence in Irish archaeology, all point to the potential to expand this chronology both spatially and temporally, and demonstrate T. baccata's potential in multi-site and multi-species tree-ring studies in the region

The effects of aridity on conifer radial growth, recruitment, and mortality patterns in the eastern sierra nevada, california

Understanding natural variability in precipitation and drought, and the resulting effects on Sierra Nevada forests, is crucial for successful resource management in this environmentally sensitive area of California. This study assessed the species-specific influence of precipitation variations on radial growth, recruitment, and mortality patterns for three conifer species (Pinus jeffreyi, Juniperus occidentalis, and Pinus contorta) in two mid-elevation lake catchments over the past 550 years. The P. jeffreyi chronology was the most highly correlated with winter precipitation patterns, although the other two species also exhibited significant correlations. Ring-width patterns suggest the influence of the Pacific Decadal Oscillation (PDO) and El Nino-Southern Oscillation (ENSO) on winter precipitation over the length of the records. Recruitment patterns displayed significant, though directionally distinct, correlations with winter drought: P. contorta exhibited increased recruitment during extended drought periods, while P. jeffreyi and J. occidentalis showed increased recruitment during wetter intervals. Finally, a ring of dead trees around both lakes is evidence of a late 20th century water level rise, likely caused by earlier snowmelt and/or wetter conditions. Moisture availability has exerted a strong influence on Sierra Nevada forests through time, but the strength of tree-growth response, and even the sign of tree population response, has been species-specific

The long-term temperature record from Markree Observatory, County Sligo, from 1842 to 2011

This study analysed long-term temperature patterns in the north-west of Ireland using a previously unexplored data-set from Markree Observatory, County Sligo. The Markree series extends back to 1842, making it one of the longest instrumental temperature records in Ireland and is renowned for holding the lowest recorded temperature for the island of Ireland, 198C on 16 January 1881. Despite its length, this record has been largely absent from past analyses of Ireland’s long-term temperature trends, rendering spatial coverage for the extended Irish climate chronology incomplete. Daily data stored in a variety of the historical archives were gathered and digitised and monthly records created. Calibrations to account for instrumentation, time of reading and exposure were applied where possible in order to standardise the record. Trends were subsequently investigated for seasonal averages of daily minimum, maximum and mean temperatures, and a comparison with previously published long Irish temperature records was carried out to situate the Markree record among the existing long-term series. Although the Markree series follows similar patterns to the other long-term temperature records, it displays more decadal variability, particularly in its minimum values which show a higher rate of late twentieth century warming compared to the other records. Due to its geographic location and surrounding topography shielding the site from direct ocean influences and prevailing south-westerly winds, Markree displays characteristic features of a more inland station (low minimum temperatures and large diurnal ranges) even though it is located only 7 km from the Atlantic Ocean. Such findings highlight the necessity of including the Markree data-set in future Irish climate change research