1. 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

2. 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

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

4. Climate Variability and Weather Extremes

5. 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

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

7. 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
Climate Variability and Weather Extremes

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

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

10. 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

11. 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

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

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

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

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

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

17. General proxy observations for Ireland
Climate Variability and Weather Extremes

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

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

20. Climate Variability and Weather Extremes
Climate proxies AD
MWP?
MWP?
LIA?
Climate Variability and Weather Extremes

21. Instrumental Observations
Climate Variability and Weather Extremes

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

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

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

25. Climate Variability and Weather Extremes
The Future?
Change in mean June rainfall to
Change in mean Dec rainfall to
C4I Report,
Climate Variability and Weather Extremes

26. 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