NICOPP - Nitrogen Cycle in the Ocean, Past and Present

NICOPP was a joint working group of PAGES and IMAGES. It ran from 2010 to 2014.

Major sources (green arrows) and sinks (white arrows) of fixed N in the marine environment and their most important controlling factors over time (italics). From Galbraith et al., 2008, Nitrogen in Past Marine Environments, in: Capone et al. (Eds) Nitrogen in the Marine Environment, 1497-1535.

NICOPP studied Nitrogen isotope (d15N) dynamics as recorded in the sedimentary record in order to learn about the dynamics of the marine nutrient cycle in the Quaternary and the present.

Marine nutrient cycling is a globally important biogeochemical process that, if perturbed, can shift carbon and nutrient budgets significantly within the Earth System, with immediate implications for global climate. However, projections for the coming decades disagree even on the sign of the cumulative climatic feedback of marine nutrient cycling and associated biological changes. If we wish to be able to meaningfully assess the potential impact of marine nutrient cycling on ecosystems and atmospheric composition, and ultimately the feedbacks with the climate system, we need to better understand the processes and effects involved. The large oceanographic and biogeochemical changes that occurred during the last glacial cycle provide pronounced and accessible targets for paleoceanographic studies (reconstruction and modeling) of marine nutrient cycles.

Nitrogen cycling is considered to be a dominant component of the marine biogeochemistry, and was the focus of this working group. With nitrogen isotopes there is a paleo-oceanographic proxy that seems well understood and frequently applied.

Accordingly, NICOPP aimed to compile a quantitative global synopsis of the d15N data, to reveal patterns of nitrogen cycling processes, such as N-fixation, denitrification, and nitrate utilization, and to synthesize the findings and implications.