Investigating the timing and causes of nitrogen cycle changes in Bronze Age Ireland

Around 3000 cal BP, a permanent shift in herbivore δ15N values was identified, persisting through the Iron Age, but this shift is not immediately reflected in sediment sequences. Two lake sites show permanent nitrogen enrichment beginning around 2600 cal BP, peaking around 1500 cal BP, associated with renewed anthropogenic activity. The research also examines the role of climate, suggesting that droughts may have sustained elevated δ15N values during periods of reduced human impact.

This highlights a complex interaction between climate and human land-use. The findings challenge traditional assumptions about the timing of human impacts on the nitrogen cycle, suggesting earlier and more gradual changes. The thesis advocates for re-evaluating the onset of the Anthropocene, proposing that significant anthropogenic environmental changes may date back to prehistory.<br><br><i>Thesis embargoed until 31 December 2029.</i>