The dog cockle, Glycymeris glycymeris (L.), a new annually-resolved sclerochronological archive for the Irish Sea

► Glycymeris glycymeris is assessed as a scleroclimatological proxy archive. ► G.glycymeris is shown to exhibit annual periodicity of growth line formation. ► A growing season is identified from the growth series of G.glycymeris. ► Two populations of G.glycymeris separated by 27 km exhibit synchronous growth. ► Reconstructive skill is demonstrated for Irish Sea SST's and the winter NAO index.