The shelf seas are potentially important long term sinks for atmospheric carbon dioxide, either by long-term storage of carbon in coastal habitats or marine sediments, or by efficiently exporting carbon off the continental shelf into the deep ocean, where it is potentially isolated from the atmosphere for hundreds of years . The shelf seas surrounding the UK are subject to large disturbance by human activities such as trawling, land reclamation, enhanced nutrient inputs from land and climate change.
As part of the NERC/Defra Shelf Sea Biogeochemistry Programme (SSB) We’ve recently had a joint project funded between UEA, Cefas and partners to investigate the size and value of the natural marine carbon sink from UK waters and how it might change in the face of different management pressures. This is a hugely exciting and novel project, bringing together oceanographers, marine ecosystem modellers and environmental economists. Typically ‘Blue Carbon’ has been considered to apply to coastal habitats (seagrasses, mangroves etc) but in this project we will extend the definition to ‘deep’ storage such as offshore marine sediments and the deep ocean interior.
The project will work with the other (observational and modelling) projects within SSB to gather the data necessary to quantify the size and nature of the ‘Blue Carbon’ sink in UK waters. This will be used as a large scale ‘case study’ for how to develop an accounting and valuation framework for Blue Carbon as might be applied to an international carbon accounting scheme in the future. We will consider the effect of future ‘forcing scenarios’ including climate change (affecting ocean circulation, ocean acidification), riverine nutrient fluxes and fishing activity, amongst others.
There are many interesting questions. Current carbon accounting frameworks implicitly assume that the place where carbon is taken out of the atmosphere is the same as the place where it’s stored (forests, for instance, store a certain amount of carbon per square kilometre). However, in UK waters carbon can be ‘fixed’ by phytoplankton which take carbon up and sink out of the surface layer. The eventual fate of this carbon can be to be ‘flushed’ out of the North sea and into the deep ocean interior. If we take management decisions that reduce the effectiveness of phytoplantkon carbon fixation in our territorial waters, this may have a knock-on effect on the deep ocean storage (the ‘continental shelf carbon pump’). Not only are there technical issues associated with this in terms of accounting and valuation, which we relish the opportunity to think about in detail and deliver a satisfactory solution to, but there are more philosophical ones too. Is that really ‘our’ carbon to claim carbon credits for? Rich, carbon intensive nations pay countries with rain forests not to cut them down, in order to ‘offset’ their carbon emissions. This is a good way to save the rain forests, but can Western countries really expect to get ‘paid’ in carbon credits to not destroy their natural carbon sinks? More likely, if full scale international carbon accounting comes into force we will have to pay if we do harm them as the net effect of this would be to end up with more CO2 in the atmosphere. Whether or not we ‘trade’ on this carbon in the future (and whether or not such trading would be a good idea), at least we will have a better idea of how valuable it is to the atmospheric carbon balance and thus how much it is worth in economic terms to keep the marine ecosystem functioning.
Would love to hear your thoughts!
Project partners: UEA, Cefas, Plymouth Marine Laboratory, NOC Liverpool, Met Office, Carbon Trust, Ocean Innovations Ltd, International Sustainability Institute (Brazil). Funders: NERC, Defra.