The Blue Carbon Initiative describes coastal ecosystems as some of the most productive on Earth. Providing us with essential ecosystem services, such as coastal protection from storms and subsequent flood risk and nursery grounds for fish. We also know that they provide another integral service - sequestering and storing "blue" carbon from the atmosphere and oceans and hence are an essential piece of the solution to global climate change.
Global engineering firm, Jacobs, published a study in 2021 by Mossman et al., which evaluates carbon accumulation in restored saltmarshes, explains factors governing carbon build up and considers the implications for carbon credits arising from such schemes. High rates of organic carbon accumulation within a managed realignment scheme were found, prompting two questions:
- Might these high rates be found at other restored marshes?
- What would this mean for the carbon offsetting potential of marsh restoration projects?
Jacobs assessment of organic carbon within a range of Environment Agency managed realignment and regulated tidal exchange (RTE) schemes in England used local partners to collect samples using a tailor-made sampling kit and instructions. Their assessment used a variety of laboratory analysis techniques to examine sediment carbon content and lidar data to assess the amount of sediment build up. Estimates of the 21 sites investigated in this study suggest they have accumulated approximately 170,000 tonnes of total organic carbon since their opening over the past 20 years.
While Jacobs not there is a need for further research, their findings suggest sites restored by managed realignment, where existing sea walls are breached to reinstate tidal inundation to the land behind, have considerable potential to accumulate carbon through deposition of sediment brought in by the tide and burial of vegetation in the site. However, while this potential has been recognised, it is not yet a common motivating factor for saltmarsh restoration, partly due to uncertainties about the rate of carbon accumulation and how this balances against the greenhouse gases emitted during site construction.
Jacobs research supported the view that managed realignment projects in such settings are likely to have significant carbon accumulation benefits. With the paper outlining further considerations that are needed to move towards a full carbon budget for saltmarsh restoration.
In addition to this, The U.K. Centre for Ecology and Hydrology (UKCEH) are leading a consortium to develop and pilot a UK Saltmarsh Carbon Code – a rigorous and scientifically-based voluntary certification standard, enabling saltmarsh carbon to be marketed and purchased by private investors, thus providing an income stream for restoration projects and supporting the achievement of national net zero goals.
Members of the consrtium, include:
- Jacobs
- Wildfowl and Wetlands Trust (WWT)
- Royal Society for the Protection of Birds (RSPB)
- University of St Andrews
- Bangor University
- Scotland's Rural College (SRUC)
- International Union for Conservation of Nature (IUCN) National Committee U.K.
- Finance Earth
The project will be supported by the U.K. Government’s Natural Environment Investment Readiness Fund (NEIRF).