Reconstructing climate from the longest-lived animals on Earth. Talk by James Scourse, Exeter University.
A number of marine and terrestrial organisms contain incremental skeletal hardparts representing annual layers akin to tree rings. This enables biological longevity to be determined and, as in dendrochronology, growth increment series can be cross-matched to construct annually-resolved floating chronologies.
If these can be cross-matched with live-collected specimens in which the age of the final increment is known, cross-dating becomes possible. In this talk James will introduce this science of sclerochronology and focus on species of bivalve mollusc with exceptional longevities, notably Glycymeris glycymeris (dog cockle) and Arctica islandica (Icelandic clam, cyprine, quahog). The latter is the longest-lived non-colonial animal known to science (over 500 years) and the talk will include an account of the discovery of this specimen and the attendant media storm.
Radiocarbon determinations from known age material enable the radiocarbon reservoir effect to be constrained and interpreted in terms of hydrographic shifts across the major climate phases of the last 1000 years. Annually- and seasonally-resolved oxygen isotopes enable seawater temperatures to be reconstructed, revealing the extent of ocean warming since the Industrial Revolution. These data reveal changing lead-lag relationships between ocean and atmosphere over this period, enable changes in sea ice to be reconstructed and tipping points within the climate system to be identified.
James Scourse’s research focuses on long-term marine climate and ecosystem change. He has lead groups at Bangor University (1985-2012) and the University of Exeter (since 2017) researching mechanisms and feedback responses in the Earth’s climate system, in particular linked to ice-ocean interaction and the impact of changes of sea level on the carbon cycle, sediment transport and ocean circulation.
He is currently leading the European Research Council 6-year Synergy SEACHANGE Project which is establishing the impact of major human cultural transitions in marine biodiversity and ecosystem functioning. His group has pioneered the development of sclerochronology, reconstructing marine climate and ecosystem change using very long-lived annually banded molluscs.Much of his research is based at sea and he has served as Chief Scientist on 11 research cruises, including as Principal Scientific Officer on the final cruise of the RRS James Clark Ross in the Antarctic in 2020.
He is currently Head of the Department of Earth and Environmental Sciences at the University of Exeter.