Aotearoa New Zealand’s marine carbon cycle in a changing climate–Current understanding and future directions

Abstract

The marine system plays a critical role in the global climate cycle, as a major control of atmospheric carbon dioxide (CO2). Marine primary production (photosynthesis) and remineralisation of organic carbon (respiration, degradation) determine the amount of CO2 sequestered in marine sediments and deep-water environments on century to millennial timescales. The stocks and fluxes of the marine carbon cycle are susceptible to global climate change impacts and other anthropogenic activities that modify key processes. Oceanographic studies of the marine carbon cycle in Aotearoa New Zealand’s Exclusive Economic Zone (NZ EEZ) and Territorial Seas over past decades have provided broad knowledge across a complex and dynamic seascape, but there remain fundamental knowledge gaps that limit identification of and response to present and future anthropogenic threats. In particular, several areas of the EEZ have been under-sampled and there are currently insufficient data to establish baselines and variability for the marine carbon cycle. We recommend that new observational technologies and ocean modelling applications be fully developed and utilised to enable development of robust predictive capability of our ocean’s response to human-induced perturbations. Future focus on oceanic nature-based solutions to accelerate CO2 uptake will require improved knowledge of the marine carbon cycle in NZ’s EEZ.