Assessing climate variability and weather extremes in Ireland through the ages Paul Leahy, Eileen Reilly, Bettina Stefanini, Ger Kiely, Michael Monk and Jason Harris. University College Cork Economic and Social History Society of Ireland Annual Conference: ‘Disasters and Change’ Mary Immaculate College Limerick 7 - 8 November 2008 Climate Variability and Weather Extremes

Climate Variability and Weather Extremes Outline Why study the climate of the past? Climatic variability and forcing Instrumental, documentary and proxy evidence of climate Was there a ‘medieval warm period’ and a ‘little ice age’? The ‘Anthropocene’ : 1750+ Future predictions Climate Variability and Weather Extremes

Why study past climate and weather? Picture: John Doheny Climate Variability and Weather Extremes

Climate Variability and Weather Extremes

Climate Variability and Weather Extremes 19th century: dynamic view of climate Early, middle 20th century view: climate is static over century timescales 1970s onwards: re-examination of climate dynamics Climate Variability and Weather Extremes

Scales of variability in the atmosphere 3000 km 5 cm Image: Max Planck Institute for Dynamics and Self-Organization Climate Variability and Weather Extremes

Climate Variability and Weather Extremes 1837: Climate Change An Essay on the Climate of Ireland in answer to the question proposed by the Academy- “Whether we have reason to believe that a change has taken place in the climate of Ireland, and if such a change has occurred, through what period can we trace it, and to what causes should we assign it” McSweeny, Joseph (M.D.) Trans. RIA Vol. XVII pp 179-233 Climate Variability and Weather Extremes

Climate Variability and Weather Extremes Climate forcings McCormick et al. Speculum 82 (2007) Climate Variability and Weather Extremes

The pre-instrumental era Crag Cave; McDermott et al., Quaternary Science Reviews 18 (1999) Climate Variability and Weather Extremes

Criteria for documentary reconstruction of climate 1. Dependence on contemporaneous reports of well established provenance 2. Critical review of the reliability of the record based on the highest standards of modern historical scholarship. Hughes & Diaz, 1994 Climate Variability and Weather Extremes

Criteria for suitable proxy climate indicators 1. Continuous throughout; dating good to calendar year 2. Well understood spatial applicability 3. Strong well defined climate signal of known seasonal applicability 4. Temporal resolution 1 year or better 5. Time-invariance in strength and nature of climate signals 6. Capable of century scale as well as interannual; decadal fluctuations 7. Ability to capture large scale fluctuations consistently over a large region. Hughes & Diaz, 1994 Climate Variability and Weather Extremes

Climate Variability and Weather Extremes Dendroarchaeology White oak (picture: H.D. Grissino-Mayer U. Tennessee, Knoxville) Climate Variability and Weather Extremes

The Belfast tree-ring chronology Living trees; building timbers; archaeological remains; fossil oaks in peat Notable tree ring minima: 1817 AD (Tambora) 536-540 AD volcanic event(s) Climate Variability and Weather Extremes

Lake Sediment Stratigraphy at Lough Inchiquin Diefendorf et al., Quaternary Research 65 (2006) Climate Variability and Weather Extremes

Peat stratigraphy at Derryville bog Caseldine & Geary The Holocene 15 (2005) Climate Variability and Weather Extremes

Speleothem analysis at Crag Cave McDermott et al., Quaternary Science Reviews 18 (1999) Climate Variability and Weather Extremes

General proxy observations for Ireland Climate Variability and Weather Extremes

The Medieval Warm Period 1052 – 1231 AD Multiproxy/documentary; Hughes & Diaz, 1994 Climate Variability and Weather Extremes

Climate Variability and Weather Extremes The Little Ice Age 1700 AD 1351 – 1831 AD Hughes & Diaz, 1994 Climate Variability and Weather Extremes

Climate Variability and Weather Extremes Climate proxies 1-2000 AD MWP? MWP? LIA? Climate Variability and Weather Extremes

Instrumental Observations Climate Variability and Weather Extremes

Climate Variability and Weather Extremes 1750+ : The Anthropocene Jones & Mann.,Reviews of Geophysics 42 (2004) Climate Variability and Weather Extremes

Decadal rainfall variability in the 20th century Annual rainfall Leahy and Kiely (in review) Climate Variability and Weather Extremes

Pitfalls: regional variability even over short timescales Annual trends in seasonal evaporation; Leahy and Kiely (in review) Climate Variability and Weather Extremes

Climate Variability and Weather Extremes The Future? Change in mean June rainfall 1960-2000 to 2021-2060 Change in mean Dec rainfall 1960-2000 to 2021-2060 C4I Report, http://www.c4i.ie/ Climate Variability and Weather Extremes

Climate Variability and Weather Extremes Conclusions Ireland has seen several prolonged climatic shifts and extreme events over the past ten millenia Terms such as MWP and LIA over-simplify the spatial and temporal variability of climate We still only have a limited knowledge of the past climate of Ireland Pitfalls: non-local reconstructions; limited proxies and regional variability Climate Variability and Weather Extremes