A Deep Dive Into Nature-Based Solutions

A comprehensive assessment of nature-based solutions that hold promise in addressing identified ocean climate-related challenges.

Created in collaboration between BIP, Imperial College London and Sketchin.

Executive Summary

This deep-dive into ocean-based climate mitigation techniques lays out various issues that the ocean ecosystem is faced with, resulting in devastating impacts on biodiversity, loss of economic value, and inhibiting the ability of the oceans to act as climate regulators. Our analysis identified biodiversity loss, sea-level rise, and extreme weather events as the most crucial topics to tackle in terms of impact, urgency, and geographical reach. The oceans themselves can provide various services to help tackle these issues, and fourteen such solutions were evaluated using a holistic, multi-dimensional framework. Mangrove restoration and conservation emerged as one of the most effective nature-based solutions providing a carbon store and climate regulation services, coastal protection, biodiversity and habitat enhancement, a source of material (wood) and wider economic return. 


The oceans play a pivotal role in sustaining life on earth, powering economies and guarding the global climate. Biodiversity is almost fully formed in the oceans: 94% of all life on Earth calls the oceans home [1]. This is transformed in economic value as 3 billion people rely on marine and coastal resources as their main source of protein [2]. In terms of climate regulation, the oceans absorb 90% of excess heat from human-made emissions [3] and provides 50-85% of all oxygen produced in the atmosphere [1]. Thus, it is clear how the oceans three-fold role is highly beneficial and necessary to human life.

The current climate crisis however is leading to a collapse in the oceans’ ecosystems, leading to devastating effects on biodiversity, economies, and the climate. From 90% of all marine animals being at risk of extinction by 2100 [4], to 2 billion potential refugees by 2100 due to sea-level rise [5], the oceans’ ecosystem’s collapse calls for immediate action.

Three main ocean-based problems stand out from our climate research, in terms of impact, urgency and geographical reach: biodiversity loss, sea-level rise, and extreme weather events. The common denominator found is the increase in greenhouse gas emissions due to anthropogenic activities. In the context of the oceans, however, it is crucial to look beyond the CO2 prism, to avoid fixating on CO2 as the only metric to tackle to reach Sustainable Development. Doing so would lead to the risk of omitting other crucial consequences of the climate crisis. Natural ecosystems and wildlife are in fact experiencing the most negative impact from the climate crisis, due to, for instance, 90% of world’s marine fish stock being fully exploited, overexploited or depleted [6].

Considering all the above facts, this project focused on exploring the existing ocean-based techniques. Several techniques to solve for GHG related problems are found: wetlands restoration and conservation, seaweed farming, floating solar, offshore wind, tidal energy, artificial upwelling, seawater carbon capture, liming and alkalinity enhancement. To solve for pollution related issues the following techniques are found: wastewater management and floating booms. Finally, to tackle the issue of unsustainable fishing, sustainable aquaculture and reduction in bottom trawling are the existing ocean-based techniques.

To have a more detailed understanding of the abovementioned techniques, a holistic and multi-dimensional framework was applied. This framework consisted of seven criteria. All criteria ranged from a score of 1 (lowest) to 5 (highest), apart from costs and trade-offs criteria for which the order was reversed (1- highest, 5-lowest).

Criterion 1
Biodiversity impact: how positive the impact of the technique is on biodiversity conservation/restoration/enhancement

Criterion 2
Pollution impact: extent to which the technique can reduce pollution in the oceans

Criterion 3
Carbon impact: extent to which the technique can sequester carbon

Criterion 4
Readiness level: technological readiness level of the technique. Whether it is at a research, development, or deployment stage

Criterion 5
Costs: capital expenditure of the technology (e.g. equipment, technology development costs, infrastructure)

Criterion 6
Trade-offs: the trade-offs that come with implementing the technology (e.g. implementation of floating booms to reduce pollution in the oceans can potentially lead to reduction in marine wildlife)

Criterion 7
Scalability: extent to which the technology can grow in the market (compound annual growth rate CAGR), its potential geographical reach, its social and political acceptance and support


Based on all aforementioned criteria, every one of the 13 identified ocean-based techniques was been placed in a prioritisation matrix. The matrix captures two main dimensions of each technique: (i) Ease of implementation and (ii) Opportunity and Potential Impact. The former, representing the y-axis, involves all criteria that is essential in developing and implementing said techniques, including Technological Readiness Level, Costs, Trade-offs and Scalability. Since all of these are essential in the success of a project, all components have been weighted equally. The latter, depicted on the x-axis, draws attention to the impacts of project on (i) carbon sequestration, (ii) ocean pollution and (iii) biodiversity. A greater weighting has been attached to carbon impacts (50%), as reducing carbon emissions is the main goal to solve the climate crisis. However, the impacts of all techniques on pollution and biodiversity has also been considered (25% each). As a result, wetlands restoration and conservation as well as seaweed farming are clearly standing out as the most promising solutions.

Techniques evaluation: prioritization matrix using component weighting with bigger focus on CO2 reductions

A New Layer: The Momentum Shift

Policymakers are driving the biodiversity and nature agenda, compelling businesses to extend their focus beyond GHG emissions and encompass nature holistically. Until recently, emphasis has been put on CO2 emissions reporting, but the landscape is now evolving towards a comprehensive approach that integrates corporate impacts on nature and biodiversity. This shift is gaining prominence through multiple key recent events, that led to the enactment of legally binding commitments through the EU Nature Restoration Law in July 2023, which represents a tangible and transformative shift in both mindset and environmental reporting practices:

  • The EU Nature Restoration Law (Jul 2023): Establishing legally binding objectives, including the protection of 20% of Europe’s Oceans and Land by 2030

Considering the current political momentum, and due to the scope of the Nature & Biodiversity Agenda which advocates for a holistic approach of conservation and restoration projects, seaweed farming was excluded. Consequently, we prioritized Wetlands Restoration and Conservation as the preeminent ocean-based techniques.

Among Wetlands Conservation and Restoration we found –

Growing seagrass meadows – these are a globally distributed group of marine flowering plants that form extensive meadows in shallow waters.

Tidal marshes – these usually fringe the interior of estuaries, bays, and low-energy inter-tidal zones.

Mangroves – these are plant species (trees and shrubs) which are tolerant to salty waters, normally growing in the intertidal zones subtropical sheltered coastlines and are the richest wetland eco system from the perspective of biodiversity.

Mangroves show the highest carbon potential, and the lowest costs. 

An Introduction
to Mangroves

The term mangrove (Rhizophoraceae) refers to various plant species (trees and shrubs) which are tolerant to salty waters. They normally grow in the intertidal zones belonging to tropical and subtropical sheltered coastlines. Mangroves are evolutionary marvels thanks to the ecosystem goods and services they offer, notably regarding their carbon sequestration and storage potential. They are a critical part of most tropical oceanic ecosystems but are currently being lost at an alarming annual rate of 2%.

Did you know?

🌱 Mangroves cover less than 1% of world’s forested lands

🌱  Total area occupied by mangroves in the world is around 18.1 million ha

🌱  Indonesia, Brazil, Nigeria, and Australia represent 41% of the total mangrove area

🌱  Contribute to 14% of carbon sequestration by the oceans


Mangroves support biodiversity, fish nurseries, reduce erosion, protect coast, and help mitigate against Climate Change.

Biodiversity, Habitat

70% of all commercially-harvested marine species depend on mangroves & salt marshes in part of their life cycles. Mangroves are import nurseries for commercial fish and shellfish, additionally supporting an enormous variety of birds, mollusks and insects.

Resource, Store 

In addition to consuming fish and shellfish from the mangroves, communities have historically used mangrove wood and other extracts for both building and medicinal purposes. Mangroves provide direct food security for million of people in coastal areas.

Coastal, Protection 

Mangrove protect the coast from erosion by reducing the flow of soil and sediment from the land into the sea. This water filtration helps to protect offshore ecosystems such as coral reefs. Mangroves also reduce the impact of waves on the shore and can drastically alleviate the impact of extreme events. This is becoming increasingly important with the threat of rising sea levels and extreme weather due to climate change.

Climate, Regulation

Trees are essential for local and global climate regulation. They stabilize temperature by creating shade and increase rainfall by storing and releasing water vapor. Mangroves are also extremely effective at storing carbon in their biomass as in the sediments they hold in place.

Economic, Benefit

By protecting coastal land and waters, mangroves ensure the survival of many species which are a source of food and income for local communities. Mangrove protect fisheries and coastal crops while providing opportunities for ecotourism.

Restoration and Conservation

As mentioned, considering the current political momentum, and due to the scope of the Nature & Biodiversity Agenda which advocates for a holistic approach of conservation and restoration projects, seaweed farming was excluded. Consequently, we prioritized Wetlands Restoration and Conservation as the preeminent ocean-based techniques.


Returns a degraded ecosystem to a pre-existing condition

Restored areas are not closed off from human activity and can be used sustainably

Yield faster and more predictable outcomes

Stakeholder involvement during the whole process


Entails prohibiting certain activities and managing the area

Common for non-profits, NGOs or public entities

Removes the factors causing degradation or loss and let nature do the work

Typical focus more on the population level of an ecosystem, one species at a time

Restoration provides opportunities for businesses for a whole-system engagement through job creation, community involvement, and creation of technical and financial capacity on ground.

Given the high cost of wetlands restoration projects and inherent uncertainty in the desired outcomes, several funding mechanisms are employed to increase the financial capacity of the local systems and to reduce the risk for those investing in the projects. The total project cost may be covered through a variety of sources including, grants, philanthropic corporate funds, and blue carbon financing.

See full report to discover the financing opportunities… 

Interested in exploring nature-based solutions for your organisation?


[1] UNESCO (2022) “Why the Ocean is so important for life on earth,” UNESCO [Preprint]. Available at: https://oceanliteracy.unesco.org/ocean-resources/#:~:text=The%20ocean%20is%20the%20largest,the%20water%20on%20the%20planet.

[2] WWF (2023) Sustainable Seafood | Industries | WWF. Available at: https://www.worldwildlife.org/industries/sustainable-seafood.

[3] UN (2023) The ocean – the world’s greatest ally against climate change | United Nations. Available at: https://www.un.org/en/climatechange/science/climate-issues/ocean#:~:text=The%20ocean%20generates%2050%20percent,the%20impacts%20of%20climate%20change.

[4] Yirka, B. (2022) “Study shows 90% of marine species at risk of extinction by 2100 if greenhouse gas emissions are not curbed,” Phys.org, 23 August. Available at: https://phys.org/news/2022-08-marine-species-extinction-greenhouse-gas.html.

[5] Cornell University (2017) Rising seas could result in 2 billion refugees by 2100 | Cornell Chronicle. Available at: https://news.cornell.edu/stories/2017/06/rising-seas-could-result-2-billion-refugees-2100.

[6] UNCTAD (2017) A man-made tragedy: the overexploitation of fish stocks. Available at: https://unctad.org/news/man-made-tragedy-overexploitation-fish-stocks#:~:text=Close%20to%2090%25%20of%20the,coast%20for%20example%20are%20overharvested.

[7] Project Drawdown (2023) Coastal Wetland Protection | Project drawdown. Available at: https://drawdown.org/solutions/coastal-wetland-protection.

[8} NOAA (2023a) Biden-Harris Administration announces $2.6 billion framework through Investing in America agenda to protect coastal communities and restore marine resources. Available at: https://www.noaa.gov/news-releases/noaa-ira-framework-2023#:~:text=Today%2C%20the%20U.S.%20Department%20of,Inflation%20Reduction%20Act%20(.

[9] Bayraktarov, E. et al. (2016a) “The cost and feasibility of marine coastal restoration,” Ecological Applications, 26(4), pp. 1055–1074. Available at: https://doi.org/10.1890/15-1077.

[10] Lewis III, R. (2001) Mangrove restoration – Costs and benefits of successful ecological restoration. Available at: http://mangrove.irwantoshut.com/Ecological_Restoration.html.

 [11] Taillardat, P. et al. (2020a) “Climate change mitigation potential of wetlands and the cost-effectiveness of their restoration,” Interface Focus, 10(5), p. 20190129. Available at: https://doi.org/10.1098/rsfs.2019.0129.

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