BIOLOGICAL CARBON PUMP ASSESSMENT USING THE TRANSPORT MATRIX METHOD AND GLOBAL NUTRIENT DISTRIBUTIONS (BATMAN)

Marine life plays a key role in the Earth's climate. To grow, marine algae extract almost as much carbon dioxide from the atmosphere annually as all plants on land. This 'primary production' fuels the marine ecosystem. The resulting waste sinks, as 'export', sequestering large amounts of carbon at depth, away from the atmosphere. Atmospheric carbon dioxide levels can be very sensitive to small changes in the depth at which recycling (or 'remineralisation') of this waste back into nutrients takes place. We have sufficient observations of sinking material to investigate the process of remineralisation but far from enough to produce a global map that could be used to test climate models. We do have such maps for nutrient distributions, that are the consequence of the remineralisation, but traditionally models take too long to run to allow such comparisons. A new technique (the Transport Matrix method) provides a means of running models much faster. In tandem with this technical development, the mechanisms controlling the process of export have become much better understood in recent years. It is timely therefore to unite these recent advances to ensure that climate models accurately capture this key process of the Earth system.

The following will benefit from this work:

i-MarNet & ESM Strategy:
The NERC and Met Office Strategy for Earth System Modelling states as a priority for future development: "The UK ocean biogeochemistry community needs to develop a common model for ESM activity building on the strengths of the existing UK models." The NERC ESM i-MarNet project has been planned to address this. However, each of the models under consideration in i-MarNet has a different representation of remineralisation. None of the models will be assessed on the accuracy and consequences of this key process as i-MarNet will not be able to run the models long enough for nutrient fields to reach equilibrium. This project will therefore contribute significantly to i-MarNet and ESM strategy, both directly, through providing recommendations on remineralisation parameterisations, and indirectly, through allowing future studies to run models quickly to equilibrium. Communication to i-MarNet and ESM strategy is facilitated by the lead PI of i-MarNet also being involved in this project.

The Met Office:
The extraction of a Transport Matrix for NEMO will provide a powerful tool that the Met Office and future partners can use for many aspects of climate modelling. The involvement of the Met Office (Totterdell) in the project will specifically involve Met Office implementation of the TMM, its transfer to the study of marine biogeochemistry and other dissolved tracers. The Met Office are also interested in the ability to easily downgrade the circulation from higher-resolution to coarser resolution in the TMM, which addresses goal two of this call.

Economists, social scientists and government:
The project and the Transport Matrix Method have considerable potential for those interested in putting an economic value on the biological carbon pump (BCP), e.g. Valuing Nature Network and The Economics of Ecosystems and Biodiversity. The BCP performs a major service to mankind by storing large quantities of carbon dioxide that would otherwise be in the atmosphere. Modelling studies have shown that the amount of carbon dioxide stored by the ocean is very sensitive to the manner in which organic material is remineralised in the ocean - the focus of this project. This project would therefore be of considerable interest for those looking to assess the magnitude (and uncertainty) of the BCP to put a value on it and the economic consequences of its change under various future scenarios.

The impact of this project on the academic community can be found described in Academic Beneficiaries