2005 IRISH SCIENTIST YEAR BOOK

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Armagh Observatory
Ana Mar�a Garc�a Su�rez
The reconstruction of climate in Ireland from tree-rings

Tree rings can provide continuous yearly palaeoclimatic records for regions of the Earth or periods with no instrumental climate data. Previous attempts to use oak tree rings from the UK and Ireland as a climate proxy have not been very successful owing to the lack of environmental stress under which such trees live. However, trees of different species are expected to react differently to changes in climate with some species more sensitive to rainfall and others to temperature or sunshine.

In a recent study we have attempted to establish, by a variety of statistical techniques, which species are suitable for climatic reconstruction in Northern Ireland and whether better reconstructions are possible with a combination of species than single species.

In order to improve the accuracy and signal to noise ratio of our reconstructions, trees grown close to the climate reference station with the longest series of meteorological records in Ireland, namely Armagh Observatory, have been selected. A careful standardisation of this 210 years old meteorological series underlies the calibration of the tree-ring climate links (see The Irish Scientist, 2001, p 75 and http://climate.arm.ac.uk ).

The results suggest that of the five species studied in Northern Ireland the deciduous species of beech and ash are the most sensitive to climate, with tree-ring growth more strongly influenced by precipitation and soil moisture in early summer than by temperature or sunshine. These meteorological parameters can also be relevant to autumn growth in the previous year. Oak is sensitive to summer rainfall and the tree-ring widths of Scots pine are more sensitive to maximum temperature and soil temperatures in winter, autumn and spring.


Comparison of the May-June rainfall at Armagh Observatory with that predicted by a combination of ash and beech tree-ring data. The red histogram represents the measured data and the black histogram, the predicted data.

Although it has not proved possible to reconstruct annual means successfully, some parameters such as rainfall and the Palmer Drought Index, and to a lesser extent maximum and mean temperatures, can be reconstructed over limited portions of the year. It has been found that combinations of species are better able to reconstruct these meteorological parameters than single species.

Contact: Ana Mar�a Garc�a Su�rez,
Armagh Observatory,
College Hill, Armagh BT61 9DG, N. Ireland;
E-mail: [email protected]