Dynamic Biological Functioning Important for Simulating and Stabilizing Ocean Biogeochemistry. Issue 4 (16th April 2018)

• Record Type: Journal Article
• Authors: Buchanan, P. J.; Matear, R. J.; Chase, Z.; Phipps, S. J.; Bindoff, N. L.
• Is Part Of: Global biogeochemical cycles. Volume 32:Issue 4(2018:Apr.)
• Page Start: 565
• Page End: 593
• Publication Date: 2018-04-16
• Subjects: nitrogen cycle -- carbon cycle -- marine ecosystem -- phytoplankton -- carbon dioxide -- climate change; Biogeochemical cycles -- Periodicals; Electronic journals; 577.1405
• DOI: 10.1002/2017GB005753
• Languages: English
• ISSNs: 0886-6236

Abstract

Abstract: The biogeochemistry of the ocean exerts a strong influence on the climate by modulating atmospheric greenhouse gases. In turn, ocean biogeochemistry depends on numerous physical and biological processes that change over space and time. Accurately simulating these processes is fundamental for accurately simulating the ocean's role within the climate. However, our simulation of these processes is often simplistic, despite a growing understanding of underlying biological dynamics. Here we explore how new parameterizations of biological processes affect simulated biogeochemical properties in a global ocean model. We combine 6 different physical realizations with 6 different biogeochemical parameterizations (36 unique ocean states). The biogeochemical parameterizations, all previously published, aim to more accurately represent the response of ocean biology to changing physical conditions. We make three major findings. First, oxygen, carbon, alkalinity, and phosphate fields are more sensitive to changes in the ocean's physical state. Only nitrate is more sensitive to changes in biological processes, and we suggest that assessment protocols for ocean biogeochemical models formally include the marine nitrogen cycle to assess their performance. Second, we show that dynamic variations in the production, remineralization, and stoichiometry of organic matter in response to changing environmental conditions benefit the simulation of ocean biogeochemistry. Third, dynamic biological functioning reduces the sensitivity of biogeochemical properties to physical change. Carbon and nitrogen inventories were 50% and 20% less sensitive to physical changes, respectively, in simulations that incorporated dynamic biological functioning. These results highlight the importance of a dynamic biology for ocean properties and climate. Plain Language Summary: The ocean's biogeochemistry is important for controlling concentrations of atmospheric greenhouse gases and therefore plays a key role in climate. An important part of ocean biogeochemistry are the numerous biological processes that occur in the ocean. In this study, we use a number of newly proposed ways to simulate the complex biological processes of the ocean. We find that these formulations provide a number of important improvements when combined. Not only do they allow the ocean model to simulate observed, regional features of ocean biology, but they also improve the simulation of ocean biogeochemistry on a global scale. We uniquely find through changing the biological and physical characteristics of the ocean that the nitrogen cycle is the most responsive to biological change, and we suggest that future assessments of ocean biogeochemical models use nitrate as a primary assessment tool. Finally, we find that including dynamic biological processes reduces the ocean's sensitivity to physical changes. Ocean biology could therefore act as a buffer to the effects of climate change through its response to environmental conditions. Key Points: Nitrate is highly sensitive to biogeochemical model parameterizations and useful for model assessment Dynamic biological functioning improves the simulated distribution of major biogeochemical fields in a global ocean model Dynamic biological functioning reduces the sensitivity of important fields, like carbon, to physical changes