Dendrochronology and the construction of climate records
The significant sectors for development in this area by several staff in the cluster include examining long-term environmental change through new techniques in isotope dendroclimatology. These are producing a unique record of summer temperature for regions where other physical climate proxies records are either unavailable or not capable of accurately reconstructing temperature at an annual resolution. To this end Dr Rod Bale is working on the application of modern proxy records to examine change within and at the end of interglacials in order to understand sea level histories.
The Modern History & Medieval Studies has a strong track record in the reconstruction of past environments and landscapes. Research and consultancy include climate reconstruction and palaeoenvironmental services in dendrochronology, geoarchaeology, GIS, human bone analysis, nautical/underwater archaeology, plant macrofossils, pollen analysis, Quaternary stratigraphy, and soil/sediment analysis.
Knowledge transfer is organised through University of Wales Lampeter Archaeological Services and consultancy projects in the School of Built and Natural Environment. Clients that have benefited include heritage and environment agencies, such as English Heritage, Cadw, the National Trust, archaeological trusts, Environment Agency, Royal Society for the Protection of Birds, National Parks, Sustainable Development Commission, Countryside Council for Wales, the Sea Trust, the Marine Energy Task Group for Wales, in addition to contractors and industry.
Funders of research include:
- Natural Environment Research Council (NERC)
Young, G.H.F., Bale, R.J., Loader, N.J., Mccarroll, D., Nayling, N. & Vousden, N. 2012, "Central England temperature since AD 1850: the potential of stable carbon isotopes in British oak trees to reconstruct past summer temperatures", Journal of Quaternary Science, , pp. n/a-n/a.DOI 10.1002/jqs.2554. Web: http://dx.doi.org/10.1002/jqs.2554
In regions with seasonal temperate climatic regimes, tree growth is rarely controlled by any single environmental factor. As a consequence, the development of robust palaeoclimate reconstructions has proved challenging. Tree-ring stable carbon isotope ratios (δ13C), however, are controlled primarily by photosynthetic rate, not by net growth. Therefore, at sites where climatic controls on tree-ring growth are not strongly expressed, a robust (isotopic) palaeoclimate signal may still potentially be preserved. This hypothesis was tested using a 160-year record of δ13C measured from the pooled latewood cellulose of six Quercus petraea L. (sessile oak) trees from Allt Lan-las in West Wales, UK. Raw δ13C values were corrected for changes in the isotopic ratio of atmospheric carbon dioxide and for changes in the behaviour of trees due to the increasing availability of atmospheric CO2 since AD 1850. Strong correlations with local summer temperature and sunshine are reported, and also with the Central England Temperature record over the full length of the isotopic chronology (AD 1850–2010) (r = 0.69, P < 0.001). We conclude that tree-ring stable isotopes can be used to extract strong palaeoclimate signals even from oak trees growing in a temperate maritime climate. This demonstrates the potential for extracting robust palaeoclimatic information from the very long and well-replicated oak chronologies which have been developed in western and central Europe primarily for dating rather than palaeoclimatic research purposes.
Hafner, P., I.Robertson, D.McCarrol, N.J. Loader, M.Gagen, R.J. Bale, H.Jungner, E.Sonninen, E.Hilasvuori, T.Levanic. 'Climate signals in the ring widths and stable carbon, hydrogen and oxygen isotopic composition of Larix decidua growing at the forest limit in the southeastern European Alps'. Trees - Structure and Function DOI 10.1007/s00468-011-0589-z
Bale, R.J., I. Robertson, M.W. Salzer, N.J. Loader, S.W. Leavitt, M. Gagen, T.P. Harlan, and D. McCarroll. 2011. 'An annually resolved bristlecone pine carbon isotope chronology for the last millennium.' Quaternary Research, Vol. 76, Issue 1, pp 22-29, July 2011. doi:10.1016/j.yqres.2011.05.004
Robertson, I, Levanic, T, Hafner, P, Gagen, M, Bale, R.J, Loader, N.J, Hilasvuori, E, Sonninen, E, Jungner, H and McCarroll, D. ‘Climatic reconstruction from larch in Slovenia’. Geophysical Research Abstracts Vol. 12. EGU general assembly.
Bale, R.J., Robertson, I., Leavitt, S.W, Loader, N.J., Harlan, T.P., Gagen, M., Young, G.H.F., Csank, A., Froyd, C., McCarroll, D. ‘Temporal stability in bristlecone pine tree-ring stable oxygen isotope chronologies over the last two centuries’. The Holocene, 20, 1.