NSFGEO-NERC: C-Streams: The Gulf Stream control of the North Atlantic carbon sink

点击翻译按钮获取中文摘要

The ocean takes up about one-quarter of the carbon dioxide (CO2) emitted by humans each year, slowing climate change. The North Atlantic Ocean is disproportionately important for anthropogenic carbon uptake. The North Atlantic also hosts a strong “natural” carbon cycle driven by both biological and physical processes. A team of scientists from the US and UK will address a fundamental knowledge gap as to how the oceanic carbon sink will evolve in the future, by focusing on the mechanisms controlling the North Atlantic carbon sink – particularly the effect of ocean circulation. This is a project jointly funded by the National Science Foundation’s Directorate for Geosciences (NSF/GEO) and the National Environment Research Council (NERC) of the United Kingdom (UK) via the NSF/GEO-NERC Lead Agency Agreement. This Agreement allows a single joint US/UK proposal to be submitted and peer-reviewed by the Agency whose investigator has the largest proportion of the budget. Upon successful joint determination of an award recommendation, each Agency funds the proportion of the budget that supports scientists at institutions in their respective countries. In addition to the US/UK collaboration, the project includes a partnership with The Island School in the Bahamas, substantial public outreach, and support for an early career postdoctoral researcher.The prevailing view of the North Atlantic’s role in carbon uptake is that it is controlled by surface fluxes, such that strengthening stratification will reduce future uptake. The project team hypothesize that the transport of nutrients and low-carbon waters by the Gulf Stream will also influence future carbon uptake over the North Atlantic. The Gulf Stream injects old nutrient rich and anthropogenic carbon-poor waters into the North Atlantic, driving some of the highest rates of CO2 uptake seen anywhere in the ocean and shaping patterns of CO2 uptake across much of the subpolar and subtropical gyres. The project objectives are to: (1) Quantify and understand the source waters that feed the Gulf Stream at Florida Straits;(2) Measure and model the processes that modify the nutrients and carbon carried by the Gulf Stream as it enters the North Atlantic; (3) Understand how the Gulf Stream affects North Atlantic carbon uptake now and into the future; (4) Disseminate this new understanding to those steering future measurements of oceanic CO2 uptake and managing our response to climate change. Specific outcomes from the project will include: (1) A two-year time series of daily physical, biogeochemical, and velocity fields across the Florida Straits, characterizing the source-point variability of Gulf Stream properties; (2) A two-year time series of dynamical and biogeochemical transports of the Gulf Stream and their southern hemisphere and recirculating components. Characterisation of the variability of these transports and how they relate to the basin-wide circulation; (3) Synthesis of the new observations with long-term in situ and satellite observations and with targeted model experiments to build an understanding of how Gulf Stream nutrient and low-carbon transports vary in relation to near-field and far-field oceanic and wind conditions and to infer how they may be changing over multi-decadal time scales.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.