CONCLUSIONS

1. Isotopic signatures of environmental change are as well preserved in Holocene fossil A. opercularis shells as in modern examples.
2. Isotopically-based estimates of seawater temperature do not lend support to Lamb's (1995) formulation of Holocene climatic variation, although the data are too limited to refute Lamb's synthesis.
3. Isotopic evidence supports the notion of lower atmospheric CO₂ levels in the pre-industrial Holocene than at present.
4. The sparse occurrence and interrupted growth of A. opercularis in the southern North Sea at present is possibly a reflection of pollution.