Never before has the urgency of climate action for ocean health been more pronounced. In September, the Intergovernmental Panel on Climate Change (IPCC) published its first Special Report on the Ocean and Cryosphere in a Changing Climate, finding that climate-induced declines in ocean health will cost the annual global economy $428 billion by 2050 and $1.98 trillion by 2100.

Now, building on this analysis, a new paper commissioned by the High Level Panel for a Sustainable Ocean Economy unpacks what these economic losses are at the country and regional level across three of the ocean-based industries – coral reef tourism, wild fisheries and mariculture (the cultivation of marine life for food).

The results are sobering. Changes to the ocean’s temperature, chemistry, flow and food webs have broad implications for our global economy. While some countries are set to maintain or improve catch and profits, billions of others around the world who rely on healthy oceans will see decreases in fish, food and prosperity. West Africa could see fish stocks decline by up to 85% due to migration to cooler waters. The North and South Atlantic, North and South Pacific, and Indian Ocean basins will see fish stocks decline by up to 30% by 2100 as fish migrate to Polar Arctic and Southern Ocean basins.

Coral reef tourism, worth $35.8 billion globally every year, could experience revenue losses of over 90% based on the current trajectory of warming.

However, if we act now, we have a path to reinforce the resilience of these ocean ecosystems and the industries that rely on them.

First and foremost, we must urgently reduce global greenhouse gas emissions from both land and ocean sources. A recent analysis commissioned by the High Level Panel for a Sustainable Ocean Economy found that ocean-based climate action could deliver up to 21% of the emissions reductions needed by 2050 to limit global temperature rise to 1.5 degrees C – demonstrating that the ocean can be a powerful part of the climate solution.

But for the impacts which are now unavoidable, decisionmakers must change the way they manage their marine resources.

1. Cooperate Across Boundaries for Wild Capture Fisheries

Wild capture fisheries produce approximately 79.3 million metric tons of fish, representing 46.4% of global seafood production and $130 billion in economic value. The industry employs 30.6 million people and operates 4.6 million fishing vessels. And for coastal communities and small island nations, small-scale fisheries are the backbone of their economies and their main source of protein.

As suitable habitats shift and change, marine species will move across jurisdictional boundaries. That will make it impossible to base management on historical benchmarks. As the climate changes, the fisheries sector will need to work to understand risks and anticipate changes and to make decisions aimed at improving ecosystem health. Regional, national, and international cooperative agreements will be necessary to ensure they are well-managed, and that the benefits are fairly distributed, during and after the transition.

In fact, our research finds under all climate scenarios that climate-adaptive fisheries management results in greater cumulative profits than business-as-usual management for 99% of countries. For many countries, catches can also be increased under certain scenarios. A constantly changing ocean requires management strategies and decisions to factor flexible, adaptive and precautionary approaches. As waters warm and acidify, fish stocks will migrate poleward, resulting in potential regional and international conflicts over shifting resources and exacerbated inequalities.

Historically, well-managed fisheries have been among the most resilient to climate change. Wider implementation of best practices in fisheries management will mitigate many of the negative impacts of climate change.

2. Expand Marine Aquaculture

Mariculture, or marine aquaculture, produces over 38.6 million metric tons of seafood worth $67.4 billion every year. This sector has great potential as a source of nutritional seafood in the future, not least in areas where fish stocks are forecast to decline.

Although climate change is expected to reduce the productivity of mariculture, the magnitude of this reduction is small relative to the sheer potential for production. For many countries, developing or expanding sustainable mariculture could help offset the negative efforts of climate change on their local fish stocks.

3. Diversify and Protect Reef-Based Economies

Ocean tourism has the potential to alleviate poverty, especially in coastal fishing and farming communities where poverty incidences are high. It can boost local and national economic development and improve local welfare. But even if tougher climate action is taken to cut greenhouse gas emissions, and climate change stabilizes, coral cover is still expected to reduce by up to 28% resulting in global economic losses of up to 66%.

Diversifying tourism activities and investments will help maintain diverse ecosystem functions, while simultaneously capturing the tourism potential of various ecosystems. Ecotourism—tourism activities that support nature conservation and education—should be prioritized to prevent exacerbating the degradation of the environmental resource base that the tourism industry depends on.

Protecting mangroves, salt marshes and seagrasses —which serve as nursery areas for coral reef fish species and trap sediment—will also serve to enhance reef health and productivity. Furthermore, reducing local threats on these interconnected habitats (such as sedimentation, nutrient pollution and overfishing) will improve the ability of coastal ecosystems to cope with warming and acidification.

Linking fisheries, aquaculture and tourism to local food and livelihood security will also improve the portfolio of policies that can be applied to reduce climate change’s impacts on local and national economies. Activities in the marine environment can also be strategically sited to reduce negative interactions and maintain healthy reefs.

An Equitable Way Forward

The steps taken to adapt these three sectors for coming climate impacts must consider the equity implications of all new and existing management decisions. Climate change will exacerbate global inequities, and inequity reduces resilience, thereby likely worsening outcomes under all climate change scenarios. Truly inclusive, representative, participatory decision-making processes are needed in all sectors to ensure procedural equity in all policy and management decisions.