Constraining the Additionality Problem for Ocean Alkalinity Enhancement
Ocean Alkalinity Enhancement (OAE) is a promising technology that could reduce atmospheric carbon dioxide (CO2) by chemically converting marine CO2 into non-gaseous carbonate compounds. Adding alkalinity would thereby allow the ocean to store more anthropogenic carbon without exacerbating ocean acidification. However, this shift in carbonate chemistry would increase the saturation state for calcium carbonate (CaCO3) which may trigger a reduction in the dissolution of CaCO3 shells, a 'natural' source of alkalinity. To constrain additionality, the net impact of OAE must account for these feedbacks. The aim of this project is to quantify additionality in global models by making experimentally-informed improvements to account for OAE-triggered reductions in CaCO3 dissolution. Constraining these feedback mechanisms between OAE and the natural alkalinity cycle is crucial to evaluate additionality and will help enable both initial proof-of-concept validation and eventual monitoring, reporting and verification.
Investigating the Additionality Effect of Ocean Alkalinity Enhancement on Air-sea Fluxes in Halifax Harbour and the Scotian Shelf
The project aims to investigate and improve our ability to quantify the additionality effect of Ocean Alkalinity Enhancement (OAE) on air-sea carbon dioxide (CO2) fluxes through combined observation and modelling at local and regional scales. Air and sea measurements of partial pressure of carbon dioxide (pCO2) , as well as other waterside carbonate system data from fixed and mobile observing ocean platforms in Halifax Harbour and on the Scotian Shelf, will be used before, throughout, and after OAE field trials. The measurements will be combined with a biogeochemical model. Two Post-Docs will synthesize observations and model output, identify the sources of uncertainties and errors in assessing the additionality of air-sea exchange, and work on mitigating and resolving them. Project outputs will be open-source and relocatable to other sites.