The role of the oceans in modulating atmospheric CO2 concentrations, and hence global climate, is related to their capacity to remove CO2 from the atmosphere and sequester it in oceanic deep waters and in underlying sediments such that it remains out of communication with the atmosphere for hundreds to thousands of years. Two mechanisms by which CO2 can be transferred to abyssal depths are via the so-called “solubility pump” and the “biological pump”. While the former can potentially be parameterized by developing accurate constraints on physical and physicochemical properties and ocean circulation, the latter is more complex, due to its tight coupling with biological processes throughout the entire oceanic water column, and is spatially and temporally heterogeneous.
Characterization of the efficacy of, and variability in the biological pump is the subject of extensive prior and on-going research. In the past two decades, ocean biogeochemical cycles studies including the US-JGOFS and large international ocean observation programs have significantly deepened the our understanding of the underlying processes, and further established the concept of the “Biological Pump” originally proposed by Volk and Hoffert, 1985, as the interplay between ocean ecosystems and the Earth’s gravity (Fig. 1). A key facet of these studies was the extensive use of time-series sediment trap (TS-trap) and advanced mooring technology that supported export flux investigations. Syntheses of available observational data on the export of particulate organic carbon (POC) and other biogenic particle fluxes to the oceanic interior provided the first glimpse of the operation of the biological pump in specific ocean basins (e.g., Fischer et al., 2003) and the world ocean (e. g., Honjo et al., 2008).
Despite these prior or on-going export studies focused either on time-series observations in specific regions, or on more process-oriented investigations, critical gaps persist in our knowledge of the workings of the biological pump. For example, there are serious information gaps for certain regions that may be particularly prone to climate-driven shifts in oceanic productivity, or where mechanisms of carbon export are complex and difficult to quantify (e.g., adjacent to continental margins). Moreover, our understanding of the interactions and feedbacks between climate change and associated changes in ocean properties (e.g., ocean acidification) and marine biota remains so rudimentary that we are unable to confidently predict whether the biological carbon pump will increase or decrease in magnitude in response to the current anthropogenic perturbations in atmospheric CO2.
We propose the initiation of a sustained, coordinated observation program to quantify critical biogeochemical fluxes and biological processes in key oceanic regions that span a broad geographic and latitudinal range, and encompass representative oceanic biomes and nutrient regimes by deploying arrays of advanced autonomous instrumentation. This observation program will profit from emerging technologies for observing ecosystem dynamics and constraining biogeochemical fluxes, and take advantage of recent advances in molecular biology and biogeochemistry in order to derive unprecedented insights into the underlying biogeochemical processes involved. In addition to providing constraints on key aspects of the oceanic biological pump, the observation program will provide a foundation for examination of a wide range of biogeochemical and ecological processes.
Another major objective of the GBF-OOI program is the provision of fundamental data and unique samples to the international ocean research and education community. Observational data and associated samples will be distributed to the community during the tenure of OOI-GBF following general OOI data/sample distribution policies.