Mr Euan Nicholas Furness – Written evidence (NSD0001)


I am a PhD research student at Imperial College London (ICL), and a fellow at the Parliamentary Office for Science and Technology (POST). These views are my own, developed through my research and interviews conducted with independent experts while at POST, and do not represent the views of ICL, POST, or any other affiliated individuals or organisations.


1. What is the potential scale of the contribution that nature-based solutions can make to decarbonisation in the UK?


Nature based solutions only have the potential to reduce net emissions by a fraction of current emissions levels. Substantial emissions reductions will also be required to reach net zero. Current sequestration rates by natural systems in the UK probably total around 40 megatons of carbon dioxide per year, which is less than 10% emissions over the same time period. This sequestration rate has the potential to be increased, but of potentially greater concern is the contribution of natural systems to emissions through degradation, especially of peatland. If nature-based solutions are to contribute further to emissions reductions then this degradation must be addressed.


I understand marine nature-based solutions more than terrestrial systems, and will focus on them throughout. The marine nature-based solutions that are most relevant to the UK are, in descending order of scientific understanding, saltmarsh, seagrass, kelp, and shelf sediments. Of these, shelf sediments are the most important for sequestering carbon: they have low sequestration rates per unit area, but cover a huge area of the UK’s seafloor. They also contain huge stores of carbon that could be emitted if the sediments were damaged by human activities. Kelp is probably the next most important, although it is not well understood enough for a firm number to be placed on its sequestration rate. Saltmarsh is the next most important, and is well understood both in terms of carbon mechanics and management options. Seagrass is probably the least important of these four systems, due to relatively low extent and sequestration rates, although it is more important (at least in terms of carbon) than a suite of other minor ecosystems.


There is no process that would increase the extent of shelf sediments, although conserving them is critical to preventing emissions. The extent of kelp in UK waters could probably be increased to around 19,000km², which might bring kelp carbon sequestration up to around 2% of current emissions, although kelp is not very well understood in the UK at present and so these figures are rather uncertain. Potential for expansion of other marine ecosystems is much lower: the next most important marine ecosystem, saltmarsh, probably has a potential to be expanded to around 640km², which would still only offset <0.1% of UK emissions. The biggest cost in saltmarsh creation is the purchase of coastal land: cost estimates range from £1m to £5m per km², although this creation can be cost effective given the non-carbon stacked benefits of saltmarsh such as biodiversity and flood defences. Costs of kelp forest creation are not known in the UK.


The co-benefits of nature based solutions often have vastly greater financial value than the carbon sequestration benefits. A lot of these co-benefits are not provided by alternative emissions reduction methods such as geoengineering or carbon capture.


2. What major scientific uncertainties persist in understanding the effects of nature-based solutions and affect their inclusion in carbon accounting, and how can these uncertainties be addressed?


Marine nature based solutions are less well understood than terrestrial nature based solutions. These uncertainties come in a variety of forms. Sequestration rates are not well constrained for marine ecosystems other than saltmarsh, and the impact of methane emissions from these ecosystems on overall carbon budgets is also uncertain, and may be substantial. For some marine ecosystems, the extent in UK waters is also very uncertain (most notably kelp).


Although disturbance of marine sediments is widely recognised to result in some amount of carbon emissions, there is very little evidence of how much carbon is released by disturbance. This makes it difficult to quantify the carbon emissions from industries such as trawl fishing.


Some marine ecosystems are precluded from inclusion in carbon budgets not just by uncertainties around their physical processes, but also by uncertainties over the appropriate framework for accounting. Kelp and marine sediments both sequester carbon in systems that span jurisdictional boundaries, and the IPCC’s guidelines on carbon sequestration by coastal ecosystems have excluded these ecosystems partly for this reason.


There is some scientific debate about the importance of marine carbonate ecosystems, such as oyster reefs and maerl beds, to carbon sequestration. Formation of carbonate (shell) traps carbon in a solid form, but also releases carbon dioxide from the water back into the atmosphere by increasing ocean acidity. Some recent reviews and reports have included carbonate systems while others have not. Consensus must be reached on the importance of these habitats in order for accounting to be viable. Carbonate geochemistry alone suggests that these systems are likely to be sources of carbon dioxide emissions rather than sinks which perform sequestration.


Removal of uncertainties will require further scientific research. This research could be funded by the private sector following the same model that is already employed by seabird conservation legislation, where precautionary estimates are made of the impact of development on carbon emissions, which incentivises developers to fund research to demonstrate that the true impact is lower than the estimate and, therefore, that the mitigation activities that they are required to perform in order to reach net zero emissions are reduced.


3. What frameworks already exist for the regulation and financing of nature-based solutions?


Saltmarsh creation can be funded through the UK Government’s High Level Stewardship agri-environment scheme. However, this scheme typically provides less funding than the ecosystem service value of the created saltmarsh. Other marine nature based solutions, which exist on seabed rather than land, are regulated by the Inshore Fisheries and Conservation Authorities (IFCAs), Marine Management Organisation (MMO), and Crown Estate. Because many marine nature based solutions are relatively new in the UK, these organisations often do not have established frameworks for regulation of these developments, which can limit the projects that are established in the UK.


There is substantial interest from the private sector in the UK in investing in nature based solutions to offset carbon emissions from individual companies. However, there is not currently an easy way for investors to connect to projects to provide funding. Finance Earth is an organisation that has some experience with designing financing vehicles for nature based solutions in the UK.


Several good examples of marine nature based solutions can be found in the UK and elsewhere: Steart Marshes in the UK provides an excellent example of how to maximise community support for a project, seagrass restoration projects in Virginia give a good example of the potential scale of implementation of some projects, and kelp forest restoration in Australia provides a rare example of how kelp can be implemented as a nature based solution.


Carbon offset markets should consider not just the carbon benefits of development, but other co-benefits as well. Otherwise, they risk encouraging developments that maximise carbon sequestration at a net cost to total environmental benefits.


The biggest challenges for carbon accounting are additionality and avoiding double counting. Additionality means that carbon accounting must consider not the total sequestration potential of a proposed habitat, but the difference between the sequestration potential of that habitat, and the sequestration that is already occurring in the existing habitat. Avoiding double counting means not measuring the same carbon sequestration twice, through two different mechanisms. The easiest way to do this is to only account for carbon produced within the environment being accounted for (so called autochthonous carbon), but this is not always logistically straightforward, and is not possible for some marine nature based solutions (such as kelp) where all long term carbon sequestration occurs away from the site of production. A different criterion will be required to account for these systems.


4. Who are the key stakeholders for the implementation of nature-based solutions in the UK? How can stakeholders’ expertise and concerns inform the incentives and requirements for implementing nature-based solutions?


For marine nature based solutions, stakeholders include conservation organisations such as the Wildfowl and Wetlands Trust (WWT), Royal Society for the Protection of Birds (RSPB), and Marine Conservation Society, land-management bodies such as the Crown Estate, IFCAs, and MMO, and industry, primarily the fishing industry.


WWT Steart Marshes provides a good example of how saltmarsh restoration projects can engage with the local community.


5. How should implementation of nature-based solutions be integrated with other government policies for landscapes and seascapes, for example, agricultural, forestry, and land-use planning policies?


Inclusion of marine nature based solutions within marine protected area planning would provide a relatively straightforward mechanism for the protection of large areas of the UK’s sediment carbon stock. This consideration has already been made in the Benyon report on proposed Highly Protected Marine Area legislation. However, marine protected areas in general do not currently protect sediment carbon stocks. Furthermore, given the extent of sediment carbon in the UK’s EEZ, marine protected areas are unlikely to be sufficient to protect sediment carbon stocks.


The 30by30 initiative for marine protected areas is especially relevant to marine nature based solutions. However, the benefits of marine protected areas to marine nature based solutions depend upon the implementation of effective protection of ecosystem services in marine protected areas: protection which is currently missing from much of the UK’s marine protected areas.


The Government’s recently published marine planning documents are also very relevant to marine nature based solutions. These include language indicating that marine activities will need to demonstrate that they have minimised and mitigated for carbon emissions resulting from damage to ecosystems, but it is not clear how these requirements will be implemented.


Future agri-environment schemes would certainly benefit from including considerations of nature-based solutions. This may especially benefit peatlands, since the uncertainty surrounding the future of agri-environment schemes post-Brexit has led to an unwillingness among landowners to commit to long-term peat restoration schemes that may turn out to be uneconomical if agri-environment policies change.


6. How should nature-based solutions be planned and monitored at the national level?


The IPCC framework on nature-based solutions lays out a hierarchy of measurements for carbon accounting in ecosystems. This hierarchy consists of three tiers. Tier 1 values are carbon sequestration values for a given habitat, based on global data, to be used in the absence of anything better. Tier 2 values are nation-specific values, and tier 3 values are site specific values. Accurate monitoring of carbon sequestration by nature based solutions will require calculation of tier 2 and 3 values for as many habitats as possible. This is more difficult for some habitats, such as kelp and sediments.


A lot of nature-based solutions are measured relative to a 1990 baseline sequestration value. An understanding of this baseline is therefore a requirement for incorporation of habitats into the UK’s national greenhouse gas inventory. While having a standard is useful, the difficulty in establishing the 1990 sequestration rates for marine nature-based solutions risks excluding them from the national greenhouse gas inventory. It is also important to note that the choice of 1990 as a baseline is arbitrary: many marine ecosystems, especially seagrass, had declined substantially in extent prior to 1990.


27 July 2021