CLIMATE CHANGE - TOWARDS ADAPTATION Blue carbon ― a new frontier

Recent research has identified ‘blue carbon’ as a possible tool for supporting New Zealand’s transition to a low-emission economy. Blue carbon, the term for carbon captured and stored by coastal ecosystems such as mangroves, salt marshes and sea meadows, is an emerging area of focus around the world. International project initiators are eyeing the role that these systems can play in climate mitigation, driven by data suggesting sequestration activity in this sphere could be disproportionately effective – and seeing the threat posed by failure to protect coastal ecosystems.

New Zealand projects

In New Zealand, a number of research projects are being undertaken to investigate the potential to use blue carbon to combat climate change. One project, being led by Blue Carbon Services and NIWA (with funding from the Ministry of Business Innovation and Employment and The Nature Conservancy), is investigating the relationship between coastal kelpbiomass and carbon sequestration in offshore marine sediments. Commercial development of open-ocean ‘kelp-farms’ could be used as an effective carbon sequestration tool, and possibly be

Like terrestrial vegetation, marine vegetation (kelp, mangroves, marshes etc.) absorbs carbon from the atmosphere through photosynthesis. This carbon is stored in the vegetation’s living biomass and in marine sediments. A proportion of the carbon captured during this process also ends up in deep ocean waters, where it can be locked away for hundreds or possibly thousands of years.19 Although blue ecosystems cover a very small proportion of the globe, studies suggest they can sequester carbon at rates between three and ten times greater than terrestrial forests, depending on the type of plant life involved.20 included in the New Zealand Emissions Trading Scheme (NZ ETS). The kelp-farms could be integrated with existing mussel aquaculture infrastructure, providing an important source of nutrition for the shellfish resulting in increased growth rates and larger, tastier mussels.21

Research is also being undertaken by the Tasman Environmental Trust into the carbon storing capacity of salt marshes and seagrasses in the Tasman region. The project is supported by Tasman District Council, local iwi and local businesses as well as Live Ocean, The Nature Conservancy and the University of Canterbury, and will provide the information that will help prioritise areas for restoration.22 The Nature Conservancy (an American-based NGO) is assessing these coastal ecosystems for their potential to help set up a market for blue carbon credits.23 The basic idea is that if it is demonstrated that these areas hold sufficient carbon, investors could pay for restoration at scale, which would generate carbon credits which have a tradeable value in the New Zealand carbon market (not to mention the potential to generate carbon credits in voluntary carbon markets, outside of the NZ ETS). Restoration of these sites would also contribute to increased flood protection, enhanced biodiversity, cleaner water, and eco-tourism opportunities.24