Study Could Shell Out Climate Findings
2 April 2008
Shell research (Sclerochronology)at the University of Derby.
Through these techniques we can estimate both the age of shells and the climatic conditions they were exposed to
”Dr Andrew Johnson, Reader in Sclerochronology.
Scientists are carrying out research to discover if the humble seashell holds the key to deciding the great climate change debate.
Experts at the University of Derby are harnessing the properties of shells using a technique called sclerochronology to ascertain their age and secure clues about the environment.
Sclerochronology is a growing global area of research that now has its own international committee – featuring Derby scientists.
The process is similar to that of dendrochronology – counting the rings of trees to determine age – and could also point reveal details about our climate stretching back three million years.
Dr Andrew Johnson, Reader in Sclerochronology, within the University's School of Science, said: "Shells begin life as a planktonic larva, which develops a protoshell. The shell develops further by accretion around the edges, and scientists can determine its age from growth rings.
"We can conduct further tests on the composition of the shells, looking at the ratio of oxygen isotopes to determine temperature.
"Through these techniques we can estimate both the age of shells and the climatic conditions they were exposed to – whether the shells lived a year ago or three million years ago.
Dr Johnson is about to embark on some exciting research to determine if shells he has collected in America dating back three million years hold the key to revealing more about the climate change process. The American research project is the latest related to shells undertaken by Dr Johnson during his academic career.
Ten years ago, he worked with Derby research student Jon Hickson to collect and analyse modern shells that live in the North Sea.
Analysing Queen Scallops or Aequipecten opercularis, the duo found that there are distinct changes in the oxygen isotopic composition of the shells.
Shell material with a relatively high ratio of oxygen-18 to oxygen-16 forms in cooler conditions while material with a lower ratio forms in warmer conditions.
Using a mass spectrometer to work out the isotopic composition of the shells, they concluded that variations in composition relate to seasonal temperature changes.
Dr Johnson and a number of his undergraduate students have been exploring microgrowth increments on shells, which offer a further climate clue to how the Earth’s climate may develop over the next century and beyond.
Within the latest research, Earth Systems Science graduate Annemarie Bird, from Shelton Lock, looked at both microgrowth increments and the isotopic composition of shells from three million years ago.
This is the most recent time in Earth history when the average temperature was higher than now, and similar to what it is predicted to become as a result of global warming.
Annemarie, who graduated at our Awards Ceremonies in January, helped analyse shells found in farmland near the village of Aldeburgh in Suffolk. Three million years ago, they would have been at the bottom of the sea.
The University has now appointed Annemarie as a part-time research assistant to work alongside Dr Johnson to take the work forward. The post started in February.
Dr Johnson also works with experts from across the world, including Dr Bernd Schöne. who is based at the University of Mainz, Germany, scientists from the British Geological Survey at Keyworth, and Dr Mark Williams, from the University of Leicester.
Dr Johnson travelled to the first-ever international conference on sclerochronology in St Petersburg, Florida, during the summer. Here he presented a paper on his research using shells to determine the Earth's climate in the Pliocene epoch (three million years ago).
While there, he also collected shells from quarries and other sites in Florida, Virginia and North Carolina to bring back home for analysis.
He is now hoping to involve undergraduate students in research projects to determine more about the climates such shells were subject to in those times – and has presented a talk to students from the University’s Student Geological Society about the challenge.
He is also holding a research seminar on April 25 at the University’s Kedleston Road site (12.15pm, room T112) where he will present the latest results and indicate prospects for future work, and will present the results at the General Assembly of the European Geosciences Union in Vienna during April.
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For more information about this news release, contact Simon Butt, Press and PR Officer, on 01332 591891 or 07748 920023, or email: s.butt@derby.ac.uk.
This press release was written by Deputy Head of Press and PR Simon Redfern on 01332 591942, or email: s.redfern@derby.ac.uk.
