Building resilience of marine ecosystems is achievable by climate-adapted conservation and management, and global stewardship

Key messages

  • The oceans play a key role in regulating the Earth’s climate. Protecting the oceans as a carbon sink including marine sediments and vegetation that bind substantial carbon stocks (“blue carbon”) is an important climate change mitigation action.
  • Integrated, tailored and innovative solutions are needed to preserve ocean ecosystems threatened by accelerating climate change and other anthropogenic pressures.
  • There is a growing recognition of the importance of integrated governance in building ocean resilience by:
    • involving all levels from local to global as well as the private sector;
    • providing clear targets, strong actions and global stewardship.
  • When expanding the global marine protected area (MPA) network, climate-smart adaptation measures include: areas with climate refugia, hotspots of change, migration corridors, biodiversity havens as well as addressing damaged areas in need of recovery.

Insight explained

Marine biodiversity is fundamental for well-functioning ecosystems (“healthy oceans”) that provide essential services and benefits for human societies. The latest projections from the Working Group I contribution to the IPCC AR6 indicate that several climate-induced anthropogenic pressures such as ocean warming, marine heat waves, ocean acidification and melting of the Arctic and Antarctic ice sheets will continue to worsen under all emissions scenarios.8,24 Improving or restoring marine life will only be possible if climate change and other anthropogenic pressures are mitigated.

With effective coordinated multi-level protection, the oceans offer triple benefits: unique biodiversity preservation, seafood provision and carbon storage. Substantially restoring key components of marine ecosystems by 2050 will be very challenging but recent findings indicate this is still achievable. Urgently, this requires new integrated, targeted and innovative solutions of ecosystem conservation and management. Ocean stressors generally do not occur in isolation, requiring management strategies that address cumulative effects. This includes cumulative-impact assessment and ecosystem-based management, which consider major interactions within an ecosystem, including those involving humans.

Effective conservation management should be guided by ocean governance that is flexible and iterative, coordinated across different levels and responsive to shifting ecological and climate dynamics as well as social norms. This is a vital requirement for effective biodiversity protection and marine ecosystem recovery. Policy making should be inclusive and adaptive; set clear targets with respect to timelines, actions, and goals; and facilitate global stewardship of the oceans. Some targets and actions that were successful in the past include exploitation bans and restrictions, endangered species legislation, habitat protection and restoration and invasive species and pollution controls.

Another necessary management component is to strive for climate-smart conservation addressing how climate change affects marine species, ecosystems, management targets and conservation efforts. It can provide climate adaptation by building resilience into the global network of MPAs by incorporating climate refugia with little projected change, areas of high environmental change and species turnover with rapid evolution potential, hotspots of thriving as well as threatened biodiversity and corridors for migrating species. Expanding the MPA network could yield 90% of maximum potential biodiversity benefits if 21% of oceans would be protected by the network, including mainly national exclusive economic zones (43%) and part of the high seas (6%) that are currently largely unprotected.

If anthropogenic pressures on marine ecosystems can be contained and restoration efforts are applied, most marine species and habitats will require one to three decades in order to return to an undisturbed state or to allow for sustainable fishing.



  • 93% – excess heat in the Earth’s climate system, as a result of increased greenhouse gas emissions from human activities, that is taken up by the ocean. About one quarter of anthropogenic greenhouse gas emissions are taken up by the oceans (and another quarter by the land).
  • 7.7% – amount of the world’s oceans that are protected via the MPA network, failing by 2.7% to reach the Aichi Biodiversity Target. A novel framework to set new goals is expected to be adopted in autumn 2021.
  • 17% – of global animal protein consumption is provided by the oceans, which is threatened by global warming. Fish stocks are projected to decline in some areas by up to 40% in the high-emission scenarios.
  • 34.2% – of fish stocks are overexploited.

Strengthening the resilience of marine ecosystems through protection and restoration as an NbS

Capturing blue carbon, the carbon that is stored and sequestered in marine sediments and coastal vegetation, is a substantial contribution to climate-smart conservation. The protection of blue carbon stocks is an important Nature-based Solution and climate-mitigation action with co-benefits for biodiversity protection. Blue carbon stocks located in Australia alone save about 23 billion USD annually in climate-mitigation costs worldwide but are threatened by climate warming and other anthropogenic pressures.25 The lack of protection of marine sediments makes their substantial carbon stocks highly vulnerable to human disturbances such as seafloor trawling and seabed mining. About aqueous 1.47 GtCO2 emissions, equivalent to about 15 – 20% of total atmospheric CO2 absorbed by the oceans each year, are bound in marine sediments.


The oceans, the largest ecosystem in the world, are a key element in the Earth and climate system. Some of their most important functions include their capacity to buffer heat, store carbon and provide food. Currently, about 17% of global animal protein consumption is provided by the oceans, which it is likely will increase with expanding global food demand. SDG 14 (“life below water”) aims at conserving the oceans and ensuring sustainable use of their resources. Many of the indicators that investigate the progress of SDG 14 show that we are not on track: for example, marine litter and ocean acidification are increasing, the expansion of the MPA network to 10% by 2020 failed and several countries have not yet fully implemented international law as reflected in the United Nations Convention on the Law of the Sea to adapt to a global ocean governance system. The United Nations Decade of Ocean Science for Sustainable Development (2021-2030) now provides a chance for countries to reach SDG14 and other SDGs that rely on a “healthy ocean”.

Implications & Recommendations

At a global level, decision makers need to:

  • strategically strengthen the global Marine Protected Areas (MPA) network (current international efforts aim at expanding the global MPA network from 7.7% to 30%) by:
    • ensuring proper representation of diverse habitats and marine biomes;
    • including corridors enabling connectivity between habitats and species movement;
  • protect blue carbon stocks beyond national jurisdictions (e.g. deep sea sediments), which requires internationally coordinated efforts;
  • develop a multi-level ocean governance system to overcome the growing challenges in marine management and conservation that:
    • acknowledges the interconnectedness of the ocean as a whole, and;
    • is coherent, responsive and adaptive to rapidly shifting ocean dynamics in time and space to allow for rapid decision-making despite uncertainty;

At a regional and local level, governments need to:

  • consider important features in sustainable management and restoration efforts including:
    • context-specific evidence-based solutions, underlying socio-ecological dynamics and connecting ocean health to human health;
  • deal with accelerating pressures and balance resource use with the protection of biodiversity and ocean ecosystem health. These efforts must be informed by:
    • marine spatial planning, ecosystem-based management and climate-smart conservation;
  • shift currently often fragmented and disconnected ocean governance to a reflexive and inclusive multi-level governance system, which would facilitate more informed policy over time as well as increased cooperation between actors at different scales across policy levels.
Figure 11: How ocean governance should work on different levels (local, national, regional and global) with examples of how this could work while implementing MPAs.

Strengthening the resilience of marine ecosystems through protection and restoration as an NbS

Figure 12: The percentage of all vulnerable, endangered or critically endangered marine species that are threatened by different anthropogenic impacts including climate change (references can be found in Martin et al., 2021). Boxes show selected individual pressures. The circle in the middle represents the marine ecosystem.

Where do we stand?

Earth system


Why care?


What to do?

Solutions and Barriers





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