Coastal Ecosystems: Blue Carbon Solutions to Climate Change

This is the first of two blogs by volunteer and nature writer Nic Wilson, exploring the critical importance of conserving and restoring coastal ecosystems of seagrasses and tidal marshes as a key nature-based solution to climate change.

The UK’s coastal habitats – our seagrass meadows, tidal saltmarshes and mudflats - lock in huge amounts of carbon. These coastal ecosystems remove carbon from the atmosphere, storing it in plants and sediment, known as ‘blue carbon’. When coastal sites are developed or damaged, they release large quantities of this carbon back into the atmosphere. Preserving our coastal habitats is vital to tackling climate change and improving human wellbeing.

Carbon Storage

Globally, mangroves, seagrasses and saltmarshes cover approximately 49 million hectares – almost double the size of the UK, and account for around 50% of the carbon stored in ocean sediments, despite accounting for less than 2% of the ocean¹. When in healthy condition, these coastal habitats capture and store carbon, but they are being destroyed at an alarming rate.

Tidal marshes have lost more than 50% of their previous global coverage and are still being destroyed at a rate of 1-2% per year, while seagrass beds are being lost at a rate of 1.5% per year with 30% of historical global coverage now gone. Scientists estimate that damaged coastal ecosystems release more than 1 billion tons of carbon dioxide, the equivalent of 19% of emissions from global tropical deforestation.²

Research funded by the Scottish government over the last two years has recently revealed Scottish marine stores of carbon (in the top 10cm of marine sediment) are approximately 18 times as large as carbon stores in Scottish forests. We must manage and protect our vital marine stores of carbon, so they do not contribute to future global warming.³

Habitat Loss

Our coastlands provide crucial resources for people, we use them for so many different things – fishing, tourism and leisure, infrastructure and farming. But this is putting them under immense pressure and stunting their ability to store carbon and provide homes for wildlife. Since the Second World War much of our coastal habitat has been lost, including 5,000 hectares of shingle (46% of the UK’s resource), 16,000 hectares of sand dunes (18%) and 5,000 hectares of saltmarsh (15%). A further 60 hectares of protected intertidal habitat looks set to disappear per year across the UK as a result of climate change, rising sea levels and coastal squeeze if we don’t act now.⁴

^{Saltmarsh and pools provide habitat and protection  Photo; RSPB / Ben Hall}

Restoration

Losing coastal habitat could be disastrous for future generations. Over the past 25 years, more than 70 managed realignment and regulated tidal exchange schemes have been developed, providing significant benefits for wildlife and people.⁵ Although the 2,500 hectares of intertidal/coastal habitat created since 1993 is a positive step forward for climate action in the UK, it falls far short of what has already been lost, let alone what will be lost in the future. Our coast has the potential to help us adapt to climate change and store our carbon emissions if we accelerate and invest in protection and restoration of coastal ecosystems. This will reduce harmful greenhouse gas emissions and provide social, economic and environmental benefits including protection from storm surges, erosion and sea level rise, improving water quality and biodiversity, providing fisheries habitat and nature-based tourism opportunities.

Case Studies

The RSPB has delivered and managed many of the realignment schemes around the UK, particularly in England where coastal squeeze and development have exacerbated the effects of flooding. Working with partners such as the Environment Agency, we have delivered and managed more than a third of the coastal habitat created in the UK (some 880 hectares). Examples of these projects include managed realignment schemes at RSPB Medmerry and RSPB Wallasea Island.

RSPB Medmerry

The largest realignment of the open coast ever undertaken in the UK was completed in September 2013. This included the creation of c200ha of wetland habitat, and protects 348 properties and associated infrastructure from coastal flooding. The scheme, funded by the Environment Agency in partnership with the RSPB, has formed vital new intertidal habitat which will provide food and shelter for species, reduce flood risk, and capture carbon.

Wallasea Island

Wallasea Island sits within a Special Protection Area which covers the Crouch and Roach estuaries. The managed realignment scheme, supported by Defra, the Environment Agency, Natural England, Crossrail and the RSPB, has seen the creation of a ca 670 ha complex of intertidal habitat, saline lagoons & coastal grassland. In addition, Crossrail helped with the creation of saline lagoons, a creek network and grazing marsh. This new area of intertidal coastal marshland now supports a wide range of biodiversity including nationally and internationally important bird populations, and has significantly increased the carbon sequestration capacity of the reserve.

The first phase of managed re-alignment and habitat creation at Wallasea Island Photo: RSPB 

What’s next?

Coastal habitat creation and restoration must be considered as part of the ‘green recovery’ from the current covid-19 pandemic, driving recovery that works for nature and people. Large-scale delivery of new coastal habitat would provide increased benefits through increasing access for people to enjoy nature, improving their health and well-being as well as contributing to a healthy economy. In England, this would also help to achieve targets under the 25 Year Environment Plan – in particular, the commitment to create or restore ‘500,000 hectares of wildlife-rich habitat outside the protected site network, focusing on priority habitats as part of a wider set of land management changes providing extensive benefits⁶. The RSPB is keen to continue working with government to invest in nature-based solutions, such as managed realignment on the coast for a resilient economy, healthy communities and a thriving natural world.

¹ https://www.thebluecarboninitiative.org/

² https://www.thebluecarboninitiative.org/

³ https://blogs.gov.scot/marine-scotland/2020/02/24/new-blue-carbon-reports/ 

⁴ Sustainable Shores: Summary Report, RSPB, February 2018

⁵ Sustainable Shores: Summary Report, RSPB, February 2018

⁶ https://www.gov.uk/government/publications/25-year-environment-plan/25-year-environment-plan-our-targets-at-a-glance

For more information on Blue Carbon and projects in Wales and elsewhere in the UK, there is a useful briefing which can be accessed here: https://seneddresearch.blog/2019/12/17/blue-carbon-and-its-role-in-combating-climate-change/.