Paul Butler

September 2013 – present. Co-ordinator of €3.1 million Marie Curie Initial Training Network (ARAMACC: Annually Resolved Archives of MArine Climate Change). ARAMACC will involve ten PhD students and one PDRA based in eight centres across Europe, working on shell-based chronologies for the northeast Atlantic Ocean, and the environmental drivers of shell growth and the applications of sclerochronology to climate modelling and applications in the commercial and regulatory sectors. Based at School of Ocean Sciences, University of Wales, Bangor and funded by the European Union FP7.

The main focus of Paul Butler's research is the construction of precisely-dated high-resolution proxy archives for the marine environment. Some species of bivalve mollusc deposit distinct annual increments in their shells, so if the date of death of the animal is known, the whole of the shell can be dated by counting increments. Most of his research to date has concentrated on the very long-lived bivalve Arctica islandica. A. islandica has been found to live longer than five hundred years (Butler et al 2012), making it the longest lived non-colonial animal whose lifespan can be authenticated. The fact that they grow synchronously within populations allows subfossil shells to be dated by comparing their increment width patterns with the patterns in overlapping shells whose dates are already known, so that the length of precisley-dated archives can be extended back in time. The statistical methods used to build the archives, to compare them with environmental variables and to reconstruct the variables are similar to those used by tree-ring researchers.

Using these techniques, he was able to construct what was then the longest (at 487 years) shell-based archive using A. islandica from waters around the Isle of Man (Butler et al 2009, 2010). Subsequently (in collaboration with Dr Alan Wanamaker, a colleague on the MILLENNIUM project) a 1,357-year A. islandica archive has been built with shells from the North Icelandic Shelf. A recent paper (Wanamaker et al 2012), published in Nature Communications, builds on the Iceland archive, using radiocarbon analysis to show changes in the strength of the Atlantic Meridional Overturning Circulation during the past millennium. Stable isotope analyses of the Iceland shells is now being carried out, with the goal of reconstructing a 1,000-year record of seawater temperatures.