Explainer: Ocean circulation & heat uptake — a practical primer for teams that need to ship

The ocean has absorbed more than 90% of the excess heat trapped by anthropogenic greenhouse gases since 1970—equivalent to approximately 380 zettajoules of energy accumulated between 1971 and 2023, according to the World Meteorological Organization's 2024 State of the Global Climate report. To put this in perspective, this represents roughly 25 billion times the energy released by the Hiroshima atomic bomb. For sustainability teams operating in emerging markets, understanding ocean circulation dynamics and heat uptake mechanisms is no longer optional—it is fundamental to climate risk assessment, infrastructure planning, and meeting increasingly stringent disclosure requirements. This primer distills the essential science, identifies what approaches are gaining traction, and provides actionable guidance for teams that need to translate oceanographic complexity into practical decisions.

Why It Matters

Ocean heat content (OHC) reached a new record high in 2024, with the upper 2,000 meters of the global ocean warming at an accelerating rate of approximately 1.05 watts per square meter. This thermal loading has profound implications that cascade through physical, ecological, and economic systems. The 2024-2025 period has witnessed particularly dramatic manifestations: marine heatwaves affected 23% of the global ocean surface in mid-2024, the Atlantic Meridional Overturning Circulation (AMOC) showed continued weakening signals, and global mean sea level rose to 101.4 mm above 1993 baseline levels.

For emerging markets, these oceanographic shifts present asymmetric risks. Coastal cities in Southeast Asia, West Africa, and Latin America face compounding threats from accelerated sea level rise, intensified tropical cyclone activity, and disrupted monsoon patterns—all directly linked to ocean heat redistribution. The economic stakes are substantial: the World Bank estimates that by 2050, rising seas alone could force 216 million people to migrate internally, with the majority concentrated in Sub-Saharan Africa, South Asia, and Latin America. Annual damages from coastal flooding in developing nations are projected to reach $780 billion by 2050 under moderate warming scenarios.

From a corporate sustainability perspective, ocean-climate linkages increasingly influence Scope 3 emissions accounting, physical risk assessments for TCFD and ISSB disclosures, and capital expenditure decisions for coastal assets. Understanding how ocean circulation patterns modulate regional climate extremes is essential for credible transition planning and climate-resilient investment.

Key Concepts

Ocean Circulation

Ocean circulation refers to the large-scale movement of water masses driven by wind stress, density differences (thermohaline circulation), and Earth's rotation. The global overturning circulation—sometimes called the "great ocean conveyor belt"—transports heat, carbon, and nutrients across ocean basins on timescales ranging from decades to millennia. The Atlantic Meridional Overturning Circulation (AMOC) is a critical component, carrying warm surface waters northward and returning cold, dense water at depth. AMOC weakening, observed since the mid-20th century and projected to decline 24-39% by 2100, would reduce heat transport to the North Atlantic while potentially intensifying warming in the tropical Atlantic and Southern Hemisphere.

ENSO (El Niño-Southern Oscillation)

ENSO is the dominant mode of interannual climate variability, characterized by coupled ocean-atmosphere interactions in the tropical Pacific. El Niño phases feature anomalous warming of eastern Pacific surface waters, suppressing upwelling and releasing vast quantities of oceanic heat to the atmosphere. The 2023-2024 El Niño contributed approximately 0.2°C to global surface temperatures, demonstrating how ocean heat storage and release modulate year-to-year climate extremes. For emerging markets spanning the Pacific Rim, ENSO-driven precipitation anomalies drive agricultural yields, hydropower generation, and flood/drought frequency.

Scope 3 Emissions

Within greenhouse gas accounting frameworks, Scope 3 encompasses indirect emissions throughout an organization's value chain—upstream (supply chain) and downstream (product use and disposal). Ocean-climate dynamics become relevant to Scope 3 when companies assess climate risks affecting suppliers in coastal zones, shipping route disruptions from changing wind and current patterns, or portfolio exposure to marine-dependent industries. Credible Scope 3 accounting increasingly requires incorporating physical climate scenarios informed by oceanographic projections.

CAPEX (Capital Expenditure)

CAPEX decisions for coastal infrastructure, port facilities, aquaculture operations, and offshore energy installations must incorporate ocean heat uptake trajectories. Thermal expansion from ocean warming accounts for approximately 40% of observed sea level rise, directly influencing design flood levels, structural specifications, and asset lifetimes. The 2024 IPCC Synthesis emphasizes that infrastructure built today will operate under substantially different ocean conditions by mid-century.

Sea Level Rise

Global mean sea level is rising at approximately 4.5 mm per year (2014-2023 average), accelerating from 2.1 mm per year in 1993-2002. Ocean thermal expansion and land ice melt contribute roughly equally at present, but ice sheet dynamics introduce significant uncertainty into long-term projections. For emerging market coastal zones, regional sea level rise often exceeds global averages due to land subsidence, gravitational fingerprinting effects, and dynamic ocean circulation changes.

Additionality

In climate finance and carbon markets, additionality refers to emission reductions or removals that would not have occurred without the specific intervention being credited. Ocean-based carbon dioxide removal approaches—including ocean alkalinity enhancement, macroalgae cultivation, and artificial upwelling—face particularly rigorous additionality standards given the complexity of marine carbon cycle monitoring and verification.

What's Working and What Isn't

What's Working

Argo Float Network Expansion: The global Argo program, comprising over 4,000 autonomous profiling floats, now provides unprecedented real-time ocean heat content monitoring to 2,000 meters depth. The Deep Argo extension to 6,000 meters is filling critical data gaps in abyssal warming. This infrastructure enables improved seasonal forecasting for emerging markets and supports empirical validation of climate models used in risk assessment.

Integrated Ocean-Climate Services: National meteorological agencies in Indonesia, India, and Brazil have successfully operationalized ocean-atmosphere coupled forecasting systems that translate ocean heat anomalies into actionable precipitation and temperature outlooks. Indonesia's BMKG ocean monitoring program has demonstrably improved El Niño impact preparedness for agricultural communities, with documented yield preservation benefits exceeding $200 million during the 2023-2024 event.

Blue Carbon Finance Mechanisms: Mangrove and seagrass restoration projects in the Sundarbans (Bangladesh-India), the Mekong Delta (Vietnam), and coastal Kenya are attracting blended finance through verified blue carbon credits. These projects deliver co-benefits including coastal protection against storm surge—directly relevant to ocean heat-driven cyclone intensification—while generating measurable carbon sequestration. The World Bank's PROBLUE initiative has mobilized >$500 million for such integrated ocean health investments.

Climate Risk Disclosure Standardization: The International Sustainability Standards Board (ISSB) climate disclosure requirements, effective for many jurisdictions in 2024-2025, are driving improved corporate assessment of ocean-related physical risks. Leading emerging market companies—including port operators in Singapore, fisheries conglomerates in Thailand, and coastal real estate developers in the UAE—are implementing scenario analysis that explicitly incorporates ocean circulation projections.

What Isn't Working

Underinvestment in Tide Gauge Networks: While satellite altimetry provides global sea level measurements, accurate local sea level projections for port and coastal infrastructure planning require dense tide gauge networks. Many emerging market coastlines have sparse or deteriorating gauge coverage, limiting the ability to detect subsidence and validate satellite data. The Global Sea Level Observing System identifies critical gaps across West Africa, the Pacific Islands, and parts of South America.

Fragmented Ocean Data Governance: Despite growing data availability, emerging market researchers and policymakers often face barriers accessing high-resolution ocean reanalysis products, downscaled projections, and proprietary shipping/offshore industry observations. The Ocean Data Interoperability Dialogue has highlighted persistent challenges in data sharing across jurisdictional boundaries, impeding integrated ocean-climate risk assessments.

Insufficient Insurance Coverage: Parametric and indemnity insurance products covering ocean-driven climate risks remain underdeveloped in emerging markets. The insurance protection gap for coastal flood and tropical cyclone damages exceeds 90% in many African and Southeast Asian nations. Munich Re data indicates insured losses from ocean-related catastrophes in emerging markets averaged just 8% of economic losses during 2020-2024, compared to 45% in developed economies.

Key Players

Established Leaders

Schlumberger (SLB): The oilfield services giant has pivoted substantially toward ocean carbon storage and monitoring technologies, leveraging subsurface expertise for marine geological sequestration.

Ørsted: The Danish energy company leads in offshore wind development across emerging markets including Taiwan and Vietnam, integrating ocean condition monitoring into asset design and operations.

Maersk: The shipping conglomerate has invested heavily in ocean route optimization and climate-resilient port partnerships, with specific focus on emerging market trade corridors.

Copernicus Marine Service (CMEMS): The European Commission's operational oceanography program provides open-access ocean forecasts and reanalysis widely used by emerging market institutions for climate services.

The Nature Conservancy: TNC operates major blue carbon and coastal resilience programs in Indonesia, Mexico, and East Africa, demonstrating scalable approaches to ocean-climate adaptation.

Emerging Startups

Sofar Ocean: Provides distributed ocean sensing through its Spotter buoy network, enabling real-time surface conditions monitoring critical for emerging market coastal hazard warning.

Saildrone: Deploys autonomous surface vehicles for ocean data collection in under-observed regions, including recent campaigns in the Indian Ocean and Gulf of Guinea.

Running Tide: Developing ocean-based carbon removal through macroalgae cultivation, with pilot deployments and emerging market partnership exploration.

CarbonRun: Specializes in ocean alkalinity enhancement monitoring and verification technologies essential for marine CDR credibility.

Greyparrot: AI-powered waste analytics startup addressing marine plastic pollution—a co-stressor that compounds ocean ecosystem vulnerability to thermal stress.

Key Investors & Funders

Green Climate Fund (GCF): The largest dedicated climate fund, with substantial ocean-climate adaptation investments across Pacific Islands, coastal Africa, and Southeast Asia.

Asian Development Bank (ADB): Active in financing climate-resilient coastal infrastructure and ocean ecosystem restoration throughout Asia-Pacific emerging markets.

The Bezos Earth Fund: Has committed $1 billion to ocean conservation and climate initiatives, including support for ocean-based CDR research and developing country capacity building.

Ocean Risk and Resilience Action Alliance (ORRAA): A multi-stakeholder coalition mobilizing finance for nature-based coastal protection, targeting $500 million in coverage by 2030.

Blue Nature Alliance: A partnership led by Conservation International, Pew, and others investing in large-scale marine protected area establishment with climate resilience co-benefits.

Examples

1. Bangladesh Coastal Resilience Program: The Bangladesh Delta Plan 2100, supported by $2.5 billion in World Bank and Netherlands financing, explicitly incorporates AMOC slowdown and accelerated Bay of Bengal sea level rise into infrastructure design. Polders and embankments protecting 20 million coastal residents are being retrofitted to accommodate projected 50-80 cm sea level rise by 2100, with monitoring buoys deployed to track ocean heat content and cyclone intensification potential in real-time.

2. Indonesia Ocean Forecast Integration: BMKG's operational coupling of ocean heat content observations with seasonal agricultural forecasts has supported over 5 million smallholder farmers in optimizing planting schedules during ENSO events. During the 2023-2024 El Niño, the system provided 3-month lead time warnings enabling rice production adjustments that avoided an estimated $350 million in losses across Java and Sulawesi.

3. Kenya Mikoko Pamoja Blue Carbon Project: This community-led mangrove restoration initiative in Gazi Bay has restored 117 hectares of mangrove forest, sequestering approximately 3,000 tonnes of CO2 annually while providing coastal protection equivalent to $400,000 in avoided erosion damages. The project has generated verified carbon credits purchased by Verra-certified buyers, demonstrating financially viable ocean-based climate solutions in emerging market contexts.

Action Checklist

• Conduct a physical climate risk assessment incorporating ocean circulation projections from CMIP6 models, specifically identifying AMOC and ENSO sensitivity of your operational geographies
• Integrate ocean thermal expansion and ice-sheet scenarios into sea level rise assumptions for coastal asset CAPEX decisions, using IPCC AR6 regional projections
• Establish Scope 3 supplier mapping for ocean-exposed supply chain nodes, prioritizing ports, fisheries, and coastal manufacturing facilities
• Subscribe to operational ocean forecast products (e.g., Copernicus Marine Service, national meteorological ocean services) for real-time monitoring of marine heatwaves and circulation anomalies
• Evaluate blue carbon and coastal nature-based solutions as climate adaptation investments with quantifiable risk reduction and carbon credit potential
• Assess insurance coverage gaps for ocean-driven physical risks and engage with parametric product providers to close protection shortfalls
• Build internal capacity for interpreting oceanographic data, considering partnerships with regional oceanographic institutions or hiring climate scientists with ocean-climate expertise
• Engage with industry initiatives (e.g., ORRAA, Getting to Zero Coalition) to share ocean-climate risk intelligence and advocate for improved emerging market data infrastructure
• Align disclosure practices with ISSB requirements by explicitly incorporating ocean-climate scenarios into TCFD-aligned climate risk reporting
• Monitor developments in marine carbon dioxide removal for potential offtake agreements or investment opportunities as methodologies mature

FAQ

Q: How does ocean heat uptake differ between tropical and polar regions, and why does this matter for emerging markets? A: Tropical oceans absorb substantial solar radiation but efficiently redistribute heat poleward through surface currents and atmospheric coupling, while polar oceans sequester heat to depth through deepwater formation. For emerging markets, this means tropical ocean surface temperatures are particularly responsive to El Niño/La Niña cycles, driving precipitation variability across monsoon regions. Polar ocean changes influence global sea level rise rates and can modulate mid-latitude weather extremes through teleconnections. Emerging markets spanning tropical and subtropical zones face the most direct exposure to ocean heat-driven cyclone intensification and coral reef degradation.

Q: What is the relationship between AMOC weakening and regional climate impacts in Africa and South America? A: AMOC weakening reduces northward heat transport, potentially cooling the North Atlantic while amplifying warming in the South Atlantic and Southern Hemisphere. Climate model projections suggest AMOC decline could shift tropical rainfall belts southward, intensifying drought conditions in the Sahel and West Africa while increasing precipitation in parts of southern Africa and northeast Brazil. Fisheries dependent on upwelling zones may also be affected as circulation patterns shift. For sustainability teams operating in these regions, AMOC scenarios should inform long-term water resource planning and agricultural adaptation strategies.

Q: How can organizations without ocean science expertise incorporate ocean-climate risks into their assessments? A: Start with accessible platforms like the IPCC Interactive Atlas, Climate Analytics' Climate Impact Explorer, or Copernicus Climate Data Store, which provide regionally downscaled ocean-climate projections. Engage with regional climate service providers—many national meteorological agencies offer sector-specific briefings. For more sophisticated analysis, partner with academic oceanography departments or consultancies specializing in climate risk (e.g., Acclimatise, Four Twenty Seven). The Ocean Risk and Resilience Action Alliance provides publicly available resources specifically designed for non-specialists assessing ocean-driven physical risks.

Q: What makes blue carbon projects different from terrestrial forest carbon credits in terms of additionality and permanence? A: Blue carbon ecosystems (mangroves, seagrasses, tidal marshes) can sequester carbon at rates 2-4 times higher per unit area than terrestrial forests, storing carbon in sediments for centuries to millennia. However, additionality verification is more complex because baseline carbon fluxes in dynamic coastal systems are difficult to establish, and permanence faces unique risks from sea level rise, coastal development, and storm damage. Credible blue carbon credits require robust monitoring of sediment carbon accumulation, clear demonstration that protection or restoration would not have occurred otherwise, and buffer provisions against reversal. The Verra VCS and Plan Vivo standards have developed specific blue carbon methodologies addressing these challenges.

Q: How might changes in ocean circulation affect global shipping routes and supply chain emissions? A: Ocean circulation influences shipping through surface current patterns, sea ice extent, and storm track locations. Arctic Ocean warming is opening Northern Sea Route navigation windows, potentially reducing Europe-Asia voyage distances by 40% but introducing new ice hazard and geopolitical risks. Changes in trade wind patterns could affect optimal sailing routes, with implications for both voyage times and fuel consumption. For Scope 3 emissions accounting, companies should monitor how physical ocean changes affect carrier efficiency and transit times. Some projections suggest North Atlantic storm intensification could increase voyage variability and associated emissions from routing diversions.

Sources

• World Meteorological Organization. (2024). State of the Global Climate 2023. Geneva: WMO. https://library.wmo.int/records/item/68835-state-of-the-global-climate-2023
• Cheng, L., et al. (2024). "Another Record: Ocean Warming Continues through 2023 despite El Niño Conditions." Advances in Atmospheric Sciences, 41: 1-11. https://doi.org/10.1007/s00376-024-3378-5
• IPCC. (2021). Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report. Cambridge University Press. Chapter 9: Ocean, Cryosphere and Sea Level Change.
• Ditlevsen, P., & Ditlevsen, S. (2023). "Warning of a forthcoming collapse of the Atlantic meridional overturning circulation." Nature Communications, 14: 4254. https://doi.org/10.1038/s41467-023-39810-w
• World Bank. (2021). Groundswell Part 2: Acting on Internal Climate Migration. Washington, DC: World Bank Group.
• Macreadie, P.I., et al. (2021). "Blue carbon as a natural climate solution." Nature Reviews Earth & Environment, 2: 826-839. https://doi.org/10.1038/s43017-021-00224-1
• NOAA Global Ocean Monitoring and Observing Program. (2024). Ocean Climate Indicators. https://www.pmel.noaa.gov/gtmba/
• International Sustainability Standards Board. (2023). IFRS S2 Climate-related Disclosures. IFRS Foundation.