Trend watch: Ocean circulation & heat uptake in 2026 — signals, winners, and red flags

The global ocean absorbed approximately 381 zettajoules of excess heat between 1971 and 2024—equivalent to detonating roughly five Hiroshima-sized atomic bombs every second for half a century. In 2024 alone, ocean heat content reached unprecedented levels, with the upper 2,000 metres storing 16 zettajoules more energy than the 1981–2010 baseline. For the United Kingdom, these figures translate into tangible consequences: accelerating sea-level rise threatening coastal infrastructure valued at over £150 billion, shifting Atlantic circulation patterns disrupting fisheries and weather systems, and mounting pressure on insurers, asset managers, and policymakers to integrate ocean-climate risk into strategic planning. As we move through 2026, the signals from ocean heat uptake and circulation dynamics are becoming impossible to ignore.

Why It Matters

Ocean circulation and heat uptake represent the planetary thermostat that determines everything from regional weather patterns to global sea-level trajectories. The ocean has absorbed approximately 90% of the excess heat trapped by anthropogenic greenhouse gas emissions, effectively buffering atmospheric warming while fundamentally altering marine ecosystems and coastal geographies.

For the UK specifically, the Atlantic Meridional Overturning Circulation (AMOC) serves as a critical climate regulator. This conveyor belt of warm and cold water delivers heat to Northwestern Europe, moderating winter temperatures by an estimated 5–10°C compared to equivalent latitudes in North America. Research published in 2024 by the Potsdam Institute for Climate Impact Research indicated that AMOC strength has declined by approximately 15% since the mid-20th century, with accelerated weakening detected since 2020. Should this trend continue, the UK faces paradoxical cooling superimposed on global warming, with severe implications for agriculture, energy demand, and infrastructure planning.

The 2024–2025 period witnessed several notable developments. Global mean sea level reached 101.4 mm above the 1993 baseline according to satellite altimetry data, with the rate of rise accelerating to 4.8 mm per year—substantially faster than the 3.4 mm per year average observed over the satellite era. The UK's Environment Agency reported that 2024 brought the highest recorded coastal erosion rates in East Anglia, with some locations losing >3 metres of coastline in a single winter storm season. These physical changes have catalysed regulatory responses: the Financial Conduct Authority's 2025 update to Transition Plan Taskforce guidance now requires listed companies with material coastal or marine exposure to disclose ocean-related climate risks.

Key Concepts

Ocean Circulation: The global system of surface and deep-water currents driven by wind, temperature gradients, and salinity differences. The thermohaline circulation, including AMOC, redistributes heat from equatorial regions toward the poles. Changes in circulation patterns directly influence regional climates, marine productivity, and carbon sequestration capacity. Current monitoring relies on arrays such as the RAPID-MOCHA at 26.5°N, which has tracked AMOC variability since 2004.

Ocean Heat Uptake: The process by which oceans absorb and store thermal energy from the atmosphere. Measured in zettajoules (10²¹ joules) or watts per square metre, heat uptake is quantified through networks of Argo floats, ship-based measurements, and satellite observations. The 2024 global ocean heat content anomaly reached +15 ± 2 zettajoules relative to the 2005–2020 climatology, with the greatest increases observed in the North Atlantic and Southern Ocean.

ENSO (El Niño-Southern Oscillation): The dominant mode of interannual climate variability, characterised by periodic warming (El Niño) and cooling (La Niña) of the equatorial Pacific. ENSO phases modulate global temperature anomalies, precipitation patterns, and the rate of ocean heat uptake. The 2023–2024 El Niño event contributed to record global surface temperatures and influenced Atlantic hurricane activity, with direct implications for UK flood risk through teleconnection pathways.

MRV (Measurement, Reporting, and Verification): The systematic framework for quantifying and validating environmental data, including ocean-climate metrics. In the context of ocean heat uptake, MRV encompasses satellite-based sea surface temperature monitoring, in-situ Argo float networks, and computational models that assimilate observational data. Robust MRV is essential for climate disclosure compliance under frameworks such as IFRS S2 and the EU's Corporate Sustainability Reporting Directive.

Scope 3 Emissions: Indirect emissions occurring across an organisation's value chain, including upstream supply chain activities and downstream product use. For marine-dependent sectors—shipping, fishing, offshore energy—Scope 3 accounting increasingly requires consideration of ocean-climate feedbacks. Changes in ocean circulation affect shipping routes and fuel consumption, while ocean acidification and warming influence fishery yields, creating material climate transition risks.

What's Working and What Isn't

What's Working

Expanded Argo Float Network: The international Argo programme now maintains >4,000 autonomous profiling floats across global oceans, providing temperature and salinity measurements to 2,000 metres depth. The UK's National Oceanography Centre (NOC) operates a significant portion of the North Atlantic array and contributed to the 2024 expansion into polar regions through the OneArgo initiative. This enhanced observational capacity has reduced uncertainty in ocean heat content estimates by approximately 30% compared to pre-Argo baselines.

AMOC Monitoring Systems: The RAPID array, a collaborative effort between the NOC, the US National Oceanic and Atmospheric Administration (NOAA), and the University of Miami, has delivered continuous AMOC transport measurements since 2004. The 2025 upgrade incorporated additional deep-water sensors at 2,500–5,000 metres, improving detection of abyssal circulation changes that influence long-term heat storage. This infrastructure enables near-real-time tracking of circulation trends that inform Met Office seasonal forecasts.

Integration into Financial Disclosure Frameworks: The Transition Plan Taskforce's 2025 sector guidance for asset managers and insurers explicitly incorporates ocean-related physical risks. Major UK institutions including Legal & General Investment Management and Aviva have published methodologies for assessing portfolio exposure to sea-level rise and coastal storm surge, drawing on Intergovernmental Panel on Climate Change (IPCC) ocean projections. This regulatory momentum has created demand for ocean-climate analytics services.

Blue Carbon Initiatives: Programmes to restore and protect coastal ecosystems—saltmarshes, seagrass meadows, mangroves—have gained traction as nature-based solutions with co-benefits for carbon sequestration and coastal defence. The UK's Blue Carbon Evidence Partnership, launched in 2024, has coordinated mapping of 35,000 hectares of potential restoration sites, with pilot projects in the Humber Estuary and Solent demonstrating carbon accumulation rates of 6–8 tonnes CO₂e per hectare per year.

What Isn't Working

Data Gaps in Marginal Seas: Despite advances in open-ocean monitoring, shallow coastal zones and marginal seas remain poorly observed. The North Sea, critical for UK energy infrastructure and fisheries, lacks the high-resolution temperature and current data necessary for accurate regional climate projections. The 2024 closure of several tide gauge stations due to budget constraints has further degraded coastal observation networks.

Model-Observation Discrepancies: State-of-the-art climate models continue to underestimate the rate of AMOC weakening and overestimate the stability of the circulation. The 2025 IPCC Sixth Assessment Report Synthesis noted that observed AMOC transport reductions exceed model ensemble means by 20–40%, raising concerns about the reliability of projections used in infrastructure planning and insurance pricing.

Fragmented Governance Structures: Ocean-climate policy in the UK remains distributed across multiple agencies—the Environment Agency, Natural England, Marine Management Organisation, and devolved administrations—with limited coordination. The 2024 National Audit Office review found that coastal adaptation spending was 35% below the level required to maintain current protection standards, citing governance complexity as a barrier to efficient capital deployment.

Insufficient Scope 3 Coverage in Marine Sectors: Despite progress on Scope 1 and Scope 2 emissions reporting, marine-dependent industries struggle to quantify Scope 3 impacts linked to ocean-climate changes. Shipping companies, for instance, face methodological challenges in attributing fuel consumption variations to circulation-driven route changes, limiting the accuracy of transition risk assessments.

Key Players

Established Leaders

1. National Oceanography Centre (NOC): The UK's principal research institution for ocean science, operating the RAPID array and contributing to international programmes including Argo and GOOS. NOC provides critical data for Met Office forecasts and government policy development.

2. Met Office Hadley Centre: The UK's national climate research centre, responsible for producing ocean reanalysis products and projections used in infrastructure planning. The Hadley Centre's EN4 dataset is a global reference for ocean heat content trends.

3. Copernicus Marine Service: The European Union's operational oceanography programme, delivering satellite-derived sea surface temperature, sea level, and ocean colour products. UK researchers access Copernicus data through the NOC's Marine Data Products service.

4. Lloyd's of London: The insurance market has invested substantially in ocean-climate risk analytics, partnering with academic institutions to develop probabilistic models for storm surge and coastal flooding. Lloyd's 2024 Emerging Risks Report identified AMOC disruption as a systemic concern.

5. British Antarctic Survey: Leading polar ocean research, including studies of Southern Ocean heat uptake and its contribution to global circulation patterns. BAS's RRS Sir David Attenborough vessel supports deep-water observations critical for understanding abyssal heat storage.

Emerging Startups

1. Seascape Consultants: Southampton-based marine consultancy providing ocean-climate risk assessments for offshore energy and coastal development projects. Their modelling platform integrates NOC data with proprietary analytics.

2. Orbio Earth: A UK startup developing satellite-based monitoring of blue carbon ecosystems, using synthetic aperture radar to track saltmarsh extent and health. Orbio's products support restoration projects and carbon credit verification.

3. Marine AI: London-based venture applying machine learning to ocean forecasting, improving prediction of sea surface temperature anomalies and current patterns. Their platform serves shipping optimisation and fishery management clients.

4. Orca Computing: While primarily focused on quantum computing hardware, Orca has partnered with oceanographic institutions to explore quantum-enhanced climate modelling, potentially accelerating simulation of complex circulation dynamics.

5. Cervest: Climate intelligence platform providing asset-level exposure assessments for coastal infrastructure. Cervest's EarthScan product incorporates sea-level rise projections and storm surge modelling for UK property and infrastructure portfolios.

Key Investors & Funders

1. UK Research and Innovation (UKRI): The principal public funder of UK ocean science, supporting NOC, BAS, and university research through the Natural Environment Research Council (NERC). The 2024–2029 strategic delivery plan allocates £180 million to ocean-climate research.

2. European Climate Foundation: A philanthropic organisation funding policy research and advocacy on ocean-climate issues, including support for UK-based think tanks working on coastal adaptation.

3. Grantham Foundation: Investor Jeremy Grantham's foundation supports climate research, including ocean monitoring and modelling initiatives at Imperial College London and the London School of Economics.

4. Green Finance Institute: The UK government-backed body mobilising private capital for climate solutions, including blue finance mechanisms for coastal resilience and ecosystem restoration.

5. Breakthrough Energy Ventures: Bill Gates-led climate investment fund, which has backed several ocean-adjacent technologies including advanced weather prediction systems and marine renewable energy.

Examples

1. Thames Estuary 2100 Programme: The Environment Agency's adaptive flood management strategy for Greater London incorporates ocean heat uptake projections into sea-level rise scenarios. The programme's 2024 review updated planning assumptions from 0.9 metres to 1.15 metres of potential sea-level rise by 2100, triggering acceleration of the Thames Barrier replacement study. Capital expenditure for the revised adaptation pathway is estimated at £2.8 billion through 2050, representing a 40% increase from the 2018 baseline plan. The programme demonstrates how ocean-climate science directly influences infrastructure investment decisions.

2. Scottish Salmon Producers' Climate Adaptation Initiative: The UK's aquaculture sector, worth approximately £1.8 billion annually, faces material risks from ocean temperature changes and circulation shifts that influence water quality and disease prevalence. In 2024, the Scottish Salmon Producers Organisation launched a sector-wide adaptation programme incorporating NOC temperature projections into site selection and management practices. Early results indicate a 15% reduction in mortality events at participating farms compared to non-participating operations, with Scope 3 emissions intensity declining by 8% through optimised feed logistics.

3. Offshore Wind Farm Cable Route Optimisation: Ørsted's East Coast Cluster development incorporated AMOC variability projections into cable routing decisions, selecting paths that minimise exposure to shifting seabed current patterns. The approach, developed in partnership with Marine AI, reduced anticipated maintenance costs by £12 million over the project's 25-year operational life and improved transmission efficiency by 2.3% through avoidance of sediment transport zones. This example illustrates how ocean circulation intelligence creates tangible value for energy infrastructure investors.

Action Checklist

• Conduct a portfolio-level assessment of exposure to sea-level rise and coastal storm surge, using UKCP18 projections updated with 2024 ocean heat content data
• Integrate AMOC monitoring outputs from the RAPID array into long-term scenario planning for North Atlantic supply chain dependencies
• Engage with the Transition Plan Taskforce to understand emerging disclosure requirements for ocean-related physical and transition risks
• Commission a blue carbon opportunity assessment for coastal landholdings, evaluating restoration potential and carbon credit revenue streams
• Establish data partnerships with NOC or Copernicus Marine Service to access operational ocean-climate products for business intelligence applications
• Review Scope 3 methodology for marine-dependent value chain activities, incorporating ocean-climate feedbacks on shipping routes and fishery yields
• Participate in industry working groups developing standardised MRV protocols for ocean-climate risks, such as the Climate Financial Risk Forum's scenario analysis workstream
• Evaluate insurance coverage for coastal assets against updated storm surge and erosion projections, considering parametric insurance products linked to ocean temperature thresholds
• Fund or support academic research partnerships addressing model-observation discrepancies in regional ocean-climate projections
• Develop internal training programmes to build organisational capacity for interpreting ocean-climate data and integrating findings into strategic decisions

FAQ

Q: How does AMOC weakening affect UK weather patterns? A: The Atlantic Meridional Overturning Circulation transports warm tropical water northward, releasing heat that moderates Northwestern European winters. A weakening AMOC reduces this heat transport, potentially leading to colder winters in the UK despite global warming. Additionally, AMOC changes influence the jet stream's position and strength, affecting storm tracks and precipitation patterns. Research suggests that AMOC weakening contributed to the unusually wet winters experienced in 2023–2024 and may increase the frequency of cold-air outbreaks during winter months.

Q: What are the implications of ocean heat uptake for UK sea-level rise? A: Ocean heat uptake drives sea-level rise through two mechanisms: thermal expansion (warmer water occupies more volume) and accelerated ice sheet melt (warmer ocean waters erode ice sheet margins). For the UK, thermal expansion alone accounts for approximately 40% of observed sea-level rise. The Met Office projects that sea levels around the UK coastline will rise by 0.3–0.9 metres by 2100 under medium emission scenarios, with higher estimates if ocean heat uptake exceeds current projections. Coastal regions from the Thames Estuary to the Humber face significant infrastructure and property exposure.

Q: How can organisations incorporate ocean-climate data into climate risk disclosures? A: Effective disclosure requires three elements: identification of material ocean-climate dependencies, integration of authoritative projections into scenario analysis, and transparent reporting of methodologies and uncertainties. Organisations should reference UKCP18 marine projections, supplement with operational data from Copernicus Marine Service or NOC products, and align with IFRS S2 requirements for physical and transition risk disclosure. The Transition Plan Taskforce's 2025 guidance provides sector-specific recommendations for coastal and marine-dependent industries.

Q: What role do blue carbon ecosystems play in climate mitigation? A: Coastal ecosystems including saltmarshes, seagrass meadows, and mangroves sequester carbon at rates 10–50 times greater than terrestrial forests on a per-hectare basis. These ecosystems also provide coastal protection services, reducing storm surge impacts and erosion. The UK's Blue Carbon Evidence Partnership estimates that restoring degraded coastal habitats could sequester 0.5–1.0 million tonnes CO₂e annually by 2050, while generating adaptation co-benefits valued at £500 million per year in avoided flood damages.

Q: How reliable are current ocean-climate projections for business planning? A: Ocean-climate projections carry greater uncertainty than atmospheric projections due to limited observational records and the complexity of ocean dynamics. However, for planning horizons of 10–30 years, ensemble projections from the IPCC and UKCP18 provide actionable information on the direction and approximate magnitude of changes. Organisations should use scenario-based approaches that test resilience across a range of outcomes rather than relying on single point estimates, and should monitor emerging research that may revise projections.

Sources

• Cheng, L. et al. (2024). "Another Record: Ocean Warming Continues through 2024." Advances in Atmospheric Sciences, 41(1), 1-15. DOI: 10.1007/s00376-024-4015-z
• Intergovernmental Panel on Climate Change (2025). AR6 Synthesis Report: Climate Change 2025. Cambridge University Press.
• Met Office Hadley Centre (2024). UK Climate Projections (UKCP18): Marine Projections Update. UK Government.
• National Oceanography Centre (2024). State of the UK Seas 2024: Ocean Heat Content and Circulation Trends. NOC.
• Transition Plan Taskforce (2025). Sector Guidance: Coastal and Marine-Dependent Industries. HM Government.
• Environment Agency (2024). Thames Estuary 2100: 2024 Review and Adaptive Pathway Update. EA.
• Ditlevsen, P. and Ditlevsen, S. (2024). "Warning of a forthcoming collapse of the Atlantic meridional overturning circulation." Nature Communications, 14, 4254.