Climate Change Solutions

Overview of Solutions Landscape

There is growing agreement that climate poses the greatest mid- and long-term threat to the marine environment; in the near-term, climate impacts on the ocean are already unfolding and becoming increasingly severe.¹  As a panel of leading marine experts framed it, “Climate change is the critical backdrop against which all future [marine] rebuilding efforts will play out.”² Without major changes, the escalating impacts of climate change will likely overwhelm marine conservation efforts. As the global ocean becomes warmer, rises higher, loses oxygen, and becomes more acidic at an ever-faster pace, substantial actions to reduce carbon dioxide emissions and facilitate adaption are required to maintain key ecosystem services and societal benefits that the ocean provides. Current trajectories of greenhouse gas (GHG) emissions are projected to result in warming by 2100 of 2.6 to 4.5 degrees Celsius above preindustrial levels; this level far exceeds the targets set out in the Paris Agreement to limit the global average temperature increase to well below 2 degrees Celsius.³

While the ocean is experiencing unprecedented physical, chemical, and biological changes due to climate change, it is also the most often-overlooked piece of the puzzle in solving the climate crisis. The ocean is humankind’s most effective buffer against climate change, as it represents the Earth’s largest heat and carbon sink. The ocean has absorbed roughly 93 percent of excess heat energy since the 1970s and also captures about a quarter of carbon dioxide emissions from anthropogenic sources.⁴ The historical silos between the marine conservation and climate mitigation communities are beginning to fade as there is growing recognition among researchers, policymakers, and practitioners that addressing the climate crisis will require an “all-hands-on-deck” approach with inputs from ocean-based measures during what is considered a decisive decade for climate action.⁴ Research by the High Level Panel for a Sustainable Ocean Economy found that under aggressive scenario assumptions, ocean-based approaches could reduce the global emissions gap by 21 percent to limit warming to 1.5 degrees Celsius, and by about 25 percent on a 2 degrees Celsius pathway by 2050.⁵

There are several frameworks for categorizing solution sets for ocean-based climate interventions. A common model is as follows:

• Mitigation measures seek to addressing the root cause of climate change by reducing greenhouse gas emissions or increasing the long-term removal of GHG emissions. This includes measures such as decarbonizing shipping, promoting marine renewables such as offshore wind and tidal energy, limiting offshore oil and gas (e.g., moratoria, restricting leasing and permitting to limit extraction), protecting coastal “blue carbon” ecosystems, promoting efficiencies in fisheries and aquaculture management, and storing carbon below the seabed.
• Adaptation measures refer to activities associated with helping communities (human and natural), industries, and countries adapt to the impacts of a changing climate. Such approaches include climate-smart spatial and fisheries management, reducing co-occurring stressors, restoring degraded habitats, increasing species resilience (e.g., assisted evolution, synthetic biology), and enhancing coastal resilience through nature-based infrastructure and managed retreat.
• Sequestration measures seek to remove carbon dioxide from the atmosphere as a means of slowing the advance of a changing climate. Sequestration measures include less technical approaches such as restoring blue carbon ecosystems (e.g., mangroves, tidal marshes, and seagrasses), in addition to technical solutions (e.g., direct carbon injection, iron fertilization).
• Cross-cutting solutions approaches such as policy engagement, communications, and advocacy generate political will and build public support for addressing the climate crisis.

This synthesis provides a light overview of interventions within this framework. As climate experts have outlined, the decision matrix for pursuing specific ocean-based measures must balance multiple criteria, including climate-related effectiveness, feasibility, co-benefits, disbenefits, governability, and cost-effectiveness.⁶

Mitigation Measures

Among ocean-based measures, ocean-based renewable energy production and decarbonizing shipping represent the greatest opportunities for emissions reductions in both the near- and long-term. In addition to mitigation potential, ocean-based climate actions areas can offer substantial co-benefits for job creation, economic benefits, improvements in air quality and human health, and promoting environmental justice and a just transition.⁷ Among individual ocean-based actions, offshore wind energy and nature-based solutions such as protecting and restoring mangroves, seagrass, and salt marshes positively impact the largest number of dimensions for the UN Sustainable Development Goals.⁸

Mitigation options for ocean-based renewable energy primarily take the form of scaling up the harnessing of offshore wind (using fixed and floating offshore wind turbines) and scaling up the use of marine renewable energy technologies (by harnessing energy from waves, tidal streams, currents, salinity gradients, and ocean thermal gradients). In comparison to offshore renewable energy which is already being deployed, marine renewable energy technologies are largely in preliminary research or pilot stages. The total installed global capacity of wind energy in 2018 was roughly 564 GW, of which 23 GW was offshore and accounted for 77 Terra-watt hours in annual production.⁹ Given that offshore wind represents less than five percent of installed global wind energy capacity, there is significant potential to scale up this resource to advance climate mitigation potential, reducing as much as 5.4 gigatons of carbon dioxide-equivalents annually by 2050.

Accelerating the scaling-up and deployment of ocean energy resources will require a combination of policy interventions and research and technological developments. Priorities for policy interventions include: support for research and development to facilitate cost reductions and scale efficiencies; economic incentives such as carbon taxes and updated power purchase agreements; marine spatial planning that integrates the future expansion of offshore renewable energy into ocean-based and coastal activities; dedicated national targets and strategies to increase the proportion of ocean-based renewable energy in a country’s energy portfolio; and development of legislation and regulations that allow for integration into national electricity grids. From a technology perspective, innovations are needed in the following areas: advancing the development of floating turbines to expand into deeper water sites and reducing costs of all ocean energy technologies even while improving their performance and reliability. Importantly, a successful energy transition must consider environmental and social dimensions (e.g., effects on ecosystems and wildlife, human health impacts, and job creation benefits).

Decarbonizing shipping and marine transport represent the second largest area of mitigation potential among ocean-based climate approaches. Shipping accounts for a significant source of global emissions (roughly three percent of global anthropogenic carbon dioxide emissions), and the sector’s emissions are expected to double in 2050 due to increased demand.¹⁰ Even as shipping represents a sizeable source of global emissions and is a key contributor to world trade and economic development, there are known and realistic pathways for reducing the sector’s climate footprint. There are opportunities to reduce emissions both from domestic shipping (i.e., shipping between ports of the same country) and international shipping (i.e., shipping between ports of different countries).

Globally, shipping has the potential for a full decarbonization of its operational emissions. Reducing emissions in shipping to net zero over the next three decades could allow for up to 61.3 Mt CO₂ of mitigation potential in 2050.¹¹ The timescale of decarbonizing shipping depends on the how quickly zero-carbon technologies can replace or retrofit current shipping vessels and infrastructure. Operational measures such as slow steaming—realized through aggressive, goal-based operational carbon intensity measures—can reduce emissions in the short term, providing 8.1 to 21.4 Mt CO₂ of mitigation potential in 2030.¹² Full decarbonization will require widespread adoption of Zero Emission Vessels (ZEVs) compatible with zero-emission ports for recharging or refueling. ZEVs can take the form of battery-powered electric ships that recharge with renewable energy or zero-carbon fuels such as green hydrogen, ammonia, or biofuel, generated with electricity from renewable energy.

As the principal governing body for the sector, the UN International Maritime Organization (IMO) has the greatest influence in shaping the future trajectory and mitigation potential of ocean-based transportation. The IMO adopted its Initial Strategy in 2018, with the goal of reducing greenhouse gases from shipping by at least 50 percent by 2050, in absolute terms relative to 2008 emissions levels. The IMO may consider even more ambitious targets when it released its Revised Strategy by 2023. There are a variety of actions that the IMO can take, along different timescales, to enable the decarbonization of the ocean-based shipping sector. Some of these measures include incentivizing operational efficiency of the existing and new fleet no later than 2030, adopting policies to reduce greenhouse gas emissions from pollutants other than carbon dioxide (e.g., methane), and setting a timetable for the industry’s transition to low- and zero-carbon fuels.

National governments also have opportunities to help decarbonize shipping, including by setting domestic targets and commitments for shipping emission reductions, and embedded emissions reductions from the sector in its Nationally Determined Contributions, as pledges for action to meet the Paris Agreement. Among technical interventions, the most significant need is to accelerate and scale the deployment of interventions in energy efficiency. Although market barriers and failures are a key obstacle, an accelerated pace in technological progress and implementation of demonstration projects will increase the application of viable solutions. The most promising solution areas that the private sector can advance (with enabling conditions from the public sector) include energy efficiency technologies (e.g., batteries, hybrid engines, air lubrication, waste heat recovery) and wind assistance technologies (e.g., kites, sails, rotors).

Coastal “blue carbon” ecosystems—including actions to conserve and restore mangroves, salt marshes, seagrasses, and to cultivate seaweed for the purpose of carbon sequestration—provide a relatively modest contribution for mitigation potential but offer a host of important socio-economic and ecological co-benefits, which makes this approach a “no-regrets” measure. Blue carbon ecosystems provide “more for the buck” than terrestrial forests from a carbon storage perspective as they cover only 1.5 percent of the area of terrestrial forests but sequester upwards of 10 times more carbon per unit area.¹³ The conservation and protection of blue carbon ecosystems, as well as the restoration of degraded ecosystems and the cultivation of seafood (macroalgae) through aquaculture has a total mitigation potential of 0.50 to 1.38 GT carbon dioxide equivalent per year by 2050.¹⁴ The important co-benefits of blue carbon ecosystems—including protecting coastlines from storms and erosion, sustaining biodiversity, and providing food security for coastal communities—reinforce the value of protecting and conserving coastal and marine ecosystems. Still, significant gaps exist in both the knowledge base and practical application of leveraging blue carbon ecosystems at scale for mitigation. The contours of priorities for a research agenda to increase the scale and effectiveness of this measure is outlined in the “Emerging Areas of Interest and Research” section below.

Similarly, reducing the carbon footprint of ocean-derived food production (wild capture fisheries and aquaculture) and potential reductions from dietary shifts towards lower-carbon proteins represent actions with relatively low mitigation potential but important co-benefits—such as improved fisheries management that increases the resilience of fisheries in the face of a changing climate. Improvements in fisheries and aquaculture management are a “no-regrets” measure, while shifting diets is considered unproven given the challenges of influencing consumption patterns.¹⁵ The High Level Panel estimates that improvements in the fisheries and aquaculture sectors, and shifting diets to include more low-carbon sources of ocean-based protein could contribute 0.48 to 1.24 Gt carbon dioxide equivalents by 2050.¹⁶ Conservation and philanthropic engagement around this approach has an opportunity to consider “win-wins” such as enhancing fisheries management to improve stock value and economic value, or expanding restorative aquaculture¹⁶ industries in ways that reduce emissions and create jobs and fisheries habitat. This approach also requires careful consideration of potential tradeoffs and unintended consequences, such as the burden of transition costs to more sustainable gear and management, and increased habitat loss if aquaculture is expanded in unproper ways.

Carbon capture and sub-seabed storage refers to a suite of technologies that capture carbon dioxide from point sources (such as industrial plants, power plants or direct air capture facilities), compress and then transporting the liquified gas it into geological formations where they remain permanently stored in porous rock several thousand meters below the seabed. While carbon capture with sub-seabed storage (“offshore CCS”) is technically proven, its deployment at industrial scale is currently limited to a few million tons of CO₂   per year. It is expected that industrial CCS may play a bigger role in the near future due to increasing CCS subsidies and the limited decarbonization strategies for key point source emissions.¹⁷

The High Level Panel estimates that offshore CCS could result in a total mitigation potential of 0.5 to 2.0 Gt carbon dioxide per year by 2050.¹⁸While some stakeholders in the marine conservation community suggest an abundance of caution around the potential risks of this approach to the ocean, others suggest that this measure is necessary to ensure that global emissions stay within a 1.5-degree-pathway. For its part, the conservation community can help advance the state of research and understanding in this field by supporting research around benefits, risks, and costs of carbon storage in the seabed.

Adaptation Measures

Adaptation measures support human and natural communities in adapting to the current and future effects of a changing climate. In general, the GHG emissions reduction potential of most adaptation measures is not well quantified. However, given that the benefits of mitigation are often not immediate from a carbon perspective, adaptation is considered a necessary component of an effective climate change response strategy. The field of research and practice for ocean-based adaptation measures is rapidly evolving. Key interventions within this category include:

• Climate-smart fisheries management: Models of business-as-usual fisheries management are expected to exacerbate the detrimental impacts of climate change, while climate-adaptive fisheries reform can help maintain fisheries health, productivity, and profits in several emissions scenarios.¹⁹ Interventions under active application include flexible harvest control rules, quota transferability, real-time data and data-limited methods, limiting commercial fishing in certain areas (e.g., high seas of the Arctic), applying seasonal closures as a management tool to protect species reproduction, applying the precautionary principles for stocks that are expected to be negatively impacted by climate change, and several other management practices.
• Climate-smart spatial management: The impacts of climate change will introduce new challenges and call for dynamic management of Marine Protected Areas (MPAs), which can help increase abundance and productivity, as well as enhance population resilience to climate-driven disturbance.²⁰  Key interventions in this category include: developing networks of MPAs, shifting MPA boundaries beyond a static form, protecting refugia, and implementing large-scale MPAs.
• Habitat protection: Research indicates that certain habitats—such as coral reefs, Arctic biota, mangroves, seagrasses, and salt marshes—are particularly sensitive to the impacts of climate change, combined with local stressors such as destructive fishing, coastal development, and pollution.²¹ Adaptation measures to protect these vulnerable habitats include reducing co-stressors, protecting critical locations, restoring degraded habitats (e.g., scaling restoration of coral reefs, seagrass, mangroves, kelp), and a suite of interventions associated with coral reefs (e.g., assisted evolution, assisted migration, synthetic biology).

Sequestration Measures

Sequestration interventions seek to remove carbon dioxide from the atmosphere as a means of slowing the advance of a changing climate. Less technical approaches—which tend are more viable, at least in the near-term—include restoring blue carbon ecosystems such as mangroves, tidal marshes,  seagrasses, and kelp. These blue carbon ecosystems can store and sequester significant amounts of carbon at higher rates, per unit area, than terrestrial forests, in addition to providing significant co-benefits such as storm protection and fisheries habitat. More technical interventions—such as iron fertilization and artificial upwelling—currently have a low level of technological readiness but may have high potential to reduce warming.

Cross-Cutting Measures

Cross-cutting actions such as policy engagement, communications, and advocacy have helped raise the profile of the ocean in climate conversations, public consciousness, and policy dialogues. In particular, the Global Climate Action Summit, the UN Oceans Conference, UNFCC Blue COP 25, and  UNFCCC Ocean-Climate Dialogues have shifted the perception of viewing the ocean less as a victim of climate change and more as a necessary tool in the toolbox to combat the global climate crisis. In October 2020, the U.S. House of Representatives introduced the Ocean-Based Climate Solutions Act of 2020, which is a comprehensive bill covering offshore drilling, offshore wind, blue carbon, shipping and ports, climate-ready fisheries, and seafood with an aim to address the climate challenge and improve resiliency. The fact that the development and introduction of an ocean-climate bill has occurred at the federal level in the U.S. is indicative of the growing profile of ocean-based climate solutions. These efforts have been boosted by the work of civil society, philanthropy, academics, and practitioners to advocate for and communicate the case for centering ocean-based action and articulating what those priorities might look like.

Potential Solution Areas That Are Underexplored or Understudied

A growing community of practitioners is exploring the ocean’s potential role in carbon dioxide removal (CDR), but these proposals remain largely theoretical and have not been tested in the field. Some stakeholders suggest that increased scientific attention is needed to understand the impacts of these proposals and advance a solutions-oriented conversation among scientists, policymakers, and the private sector to explore options for scoping, testing, and scaling ocean-based carbon dioxide removal approaches. In the past two to three years, a small but unprecedented amount of philanthropic spending has been directed at ocean-based CDR, largely focused on closing knowledge gaps and field building.

The synergistic effects of the way in which climate change interacts with other ocean stressors remains understudied. The extent to which climate impacts will alter marine ecosystems (and the communities and industries that depend on them) is directly dependent on how much warming occurs over the next century.²² Although we know that climate change is likely to exacerbate all other threats to the ocean, we lack an understanding of the projected scale of change, given that it is closely intertwined with future emissions pathways.

Knowledge Gaps and Outstanding Questions for the Field

How will climate impacts affect the resilience of Marine Protected Areas? Although well-managed MPAs can provide a solution for building resilience to climate change, many are already being impacted by ocean warming and future climate impacts may further undermine their performance.²³ Additional research is needed to understand the extent to which, and how, MPAs can address the complex and dynamic changes induced by climate change.

Despite growing interest in using blue carbon as a climate mitigation measure, there are significant gaps that exist in the knowledge base and practical application. Additional efforts are needed to create national-level inventories of blue carbon ecosystems to monitor restoration efforts more accurately and to improve quantification of carbon sequestration. From the perspective of socio-economic factors, it is critical to develop social safeguards, building upon lessons learned from forest restoration  efforts and engagement with Indigenous peoples and local communities.

Emerging Areas of Interest and Research

The marine conservation community is actively exploring a shared policy and implementation agenda for advancing ocean-based climate action. Historically, the marine conservation community has primarily approached climate change from a resilience lens to adapt to the symptoms of climate change, deferring to the climate mitigation community to address the root cause of rising emissions. Given that climate change presents the largest threat to the ocean in terms of cumulative impact,²⁴ philanthropic funders and civil society are shifting to understand how the community can strategically advance ocean-based mitigation efforts, including to support offshore wind, shipping decarbonization, blue carbon, carbon dioxide removal, and other approaches. It is clear that the world must move rapidly and systemically to reduce GHG emissions in order to avert irreversible climate impacts.²⁵ Without major changes, the mounting impacts of climate change are likely to overwhelm marine conservation efforts, which has given the conservation community invigorated momentum in understanding how it can both address climate change and reduce the ocean’s vulnerability to climate impacts.

To date, the ocean has played a relatively minor role in national climate plans and international agreements. The marine conservation community, advocates, researchers, and policy advisors are working to embed ocean-based mitigation and adaptation in key policy measures such as Nationally Determined Contributions, which represent individual country commitments to reduce national emissions and adapt to the impacts of climate change, in fulfillment of the Paris Agreement. It is expected that this work will continue through future national-level discussions and international agreements, building off of the “Blue COP” in 2019 to raise ambition around ocean-based climate action.

Climate change presents a fundamental equity challenge in that vulnerable human communities—particularly those in least developed countries and Small Island Developing States (SIDS)—are disproportionately impacted by the adverse effects of climate change, further exacerbating social inequities and increasing the likelihood of political unrest.²⁶ Philanthropy and civil society cannot address the scale of this challenge alone, but the sector can provide best practices and advocate for the inclusion of a social code of conduct to help guide conservation and policy actions. For instance, addressing livelihoods and food security impacts on coastal communities as they respond to shifts in the distribution and abundance of fish stocks will be crucial to supporting policies that are socially acceptable and ecologically effective. Similarly, the marine conservation community has an opportunity to explore how it can best support policymakers in implementing a sustainable and just ocean economy. There is increasing interest in integrating the social sciences into this conversation, particularly to ensure that “policy blindness to equity” is not perpetuated and thoughtful attention is paid to trade-offs in conservation and equity outcomes.²⁷

Typology