A groundbreaking study from the University of Cape Town's (UCT) Department of Oceanography has shed new light on the devastating impacts of the 2023-2024 El Niño event on African coastlines. Led by postdoctoral researcher Dr. Franck Eitel Kemgang Ghomsi, the research reveals record-breaking sea level surges that outpaced previous events, signaling a compounding climate crisis for the continent's vulnerable shores.

Published in Communications Earth & Environment on January 19, 2026, the study analyzed over three decades of satellite altimetry data from 1993 to 2024 across the Atlantic Ocean, Indian Ocean, Mediterranean Sea, Red Sea, and surrounding waters. This comprehensive approach highlights UCT's leadership in satellite oceanography and physical oceanography research, positioning the university as a key player in addressing Africa's climate challenges through rigorous, data-driven science.

The findings underscore how short-term climate variability like El Niño, when layered on long-term global warming, creates 'perfect storm' conditions for coastal flooding and erosion. For South African higher education institutions like UCT, this research not only advances knowledge but also informs policy, training the next generation of oceanographers equipped to tackle these threats.

El Niño-Southern Oscillation (ENSO), a recurring climate pattern characterized by the warming of ocean surface temperatures in the central and eastern tropical Pacific Ocean, has profound global repercussions. During El Niño phases, altered wind patterns and atmospheric pressure shifts disrupt normal ocean circulation, leading to widespread weather anomalies including droughts, floods, and altered sea levels.

In the context of African marine domains, ENSO influences sea levels through changes in ocean heat distribution and wind-driven upwelling. Upwelling, the process where deep, nutrient-rich waters rise to the surface, is suppressed during El Niño, trapping heat near the surface and causing thermal expansion—the primary mechanism for the observed surges. UCT researchers quantified ENSO's contribution at 4.24% of regional sea level variance, rising to 24.7% during El Niño peaks, particularly in the Western Indian Ocean.

This event's uniqueness stems from 'preconditioning': prior record-positive phases of the Indian Ocean Dipole (IOD), Atlantic Niño (ATL3), and Tropical North Atlantic (TNA) indices amplified the response. Anomalous winds further reduced upwelling, while extreme ocean stratification—measured by the Brunt-Väisälä frequency (N²)—quadrupled upper ocean heat content compared to the 2014-2016 event.

Key Findings: Record Anomalies and Accelerating Trends

The study documents a regional sea level rise of 11.26 cm since 1993, at an average rate of 3.54 mm per year—surpassing the global average of 3.45 mm/year—with acceleration of 0.14 mm/year² versus the global 0.11 mm/year². A regime shift around 2009 marked a 73% increase in rise rates, from 2.72 mm/year (1993-2008) to 4.70 mm/year (2009-2024).

• 2023-2024 El Niño detrended anomaly: 27.04 mm, exceeding 1997-1998's 19.24 mm.
• Thermal expansion: >70% of anomaly, peaking at 30 mm regionally.
• Contribution to total rise: 2.34 cm (19% since 1993).
• Regional highs: Eastern Central Atlantic (3.90 mm/year), Western Indian Ocean (3.88 mm/year).

These stats, derived from Copernicus Marine Environment Monitoring Service (CMEMS) data corrected for glacial isostatic adjustment (GIA), paint a picture of escalating risks for Africa's 38 coastal nations.

The Science Behind the Data: UCT's Methodological Rigor

Employing advanced statistical techniques like least-squares regression, quadratic fits, and bootstrap uncertainty estimation, the UCT team processed 0.25° resolution altimetry data. They deseasonalized series, removed mean cycles, and regressed against the Niño3.4 index to isolate variability. Multi-modal regression incorporated PDO, SAM, DMI, etc., while ARMOR3D provided steric heights and heat content.

Pettitt tests confirmed the 2009 shift, and t-tests validated anomalies. This multidisciplinary approach, blending physical oceanography, geodesy, and remote sensing, exemplifies UCT's Nansen-Tutu Centre's capacity-building for African scientists.

Such methods are taught in UCT's MSc and PhD programs in oceanography, training students like Moagabo Raogosha, a lecturer whose work on regional modeling complements the study.

Photo by Tadiwa Munemo on Unsplash

Regional Hotspots: From West Africa to South Africa's Shores

The Western Indian Ocean saw the strongest El Niño response, with surges threatening Mozambique, Madagascar, and Comoros. Eastern Central Atlantic hotspots endanger Nigeria's Lagos (population 15 million+), Cameroon's Douala, Ghana's Accra, and Tanzania's Dar es Salaam—over 15 million at flood risk continent-wide.

In South Africa, Cape Town's coastline faces accelerated rise at ~6.3 mm/year—double the global average—exacerbating erosion at sites like the V&A Waterfront. UCT's proximity to these risks drives its research focus, integrating local tide gauge and GNSS data for precise modeling.

Declining upwelling harms fisheries, vital for food security; suppressed nutrients cascade through marine food webs, impacting biodiversity hotspots like the Agulhas Current.

Spotlight on UCT Researchers Driving Change

Dr. Franck Eitel Kemgang Ghomsi, with PhDs in satellite oceanography and geophysics, leads from UCT's Department of Oceanography and the Nansen-Tutu Centre. His quote captures the urgency: “We are witnessing a fundamental shift... pushing sea levels to heights we have never seen.”

Co-author Dr. Moagabo Raogosha, a lecturer specializing in Benguela upwelling and Lagrangian transport, embodies UCT's blend of science and cultural insight—as a sangoma, she bridges indigenous knowledge with modern research. Their work highlights opportunities for early-career researchers in South African universities tackling climate data gaps.

Read the full study here.

Ecological and Socioeconomic Ripples

Beyond flooding, suppressed upwelling reduces productivity, threatening fisheries that support millions. Land subsidence compounds risks in deltas; Small Island Developing States like Seychelles face habitability threats. In SA, coastal tourism and ports like Durban are vulnerable, with economic losses projected in billions.

• Flooding: 15M+ exposed.
• Fisheries decline: Nutrient trapping hits food chains.
• Infrastructure: Ports, roads, water supplies at risk.

UCT's research informs resilience planning, emphasizing compound hazards.

South Africa's Coastal Vulnerabilities and UCT's Response

Cape Town exemplifies risks: dynamic shores with rocky cliffs and sandy beaches erode faster under surges. UCT's monitoring integrates satellite data with local observations, supporting city adaptation like mangrove restoration and sea walls. The department's programs train experts for national needs, aligning with SA's climate strategy.

Explore UCT's sea level trends study for SA coasts here.

Photo by kim giseok on Unsplash

Pathways to Resilience: Adaptation and Policy

Recommendations include expanded monitoring, early warnings blending science and indigenous knowledge, emissions cuts, and nature-based solutions. Models like West Africa Coastal Areas Management Program offer blueprints. UCT advocates coordinated African efforts, leveraging higher ed for capacity building.

• Enhance tide gauges/satellites.
• Build resilient infrastructure.
• Integrate local knowledge.
• Pursue net-zero by mid-century.

Future Outlook: UCT's Role in Proactive Research

Without action, 2°C warming by 2100 looms; each El Niño builds on higher baselines. UCT eyes compound hazard modeling, AI for predictions, and pan-African collaborations. For aspiring oceanographers, UCT offers MSc/PhD paths in physical oceanography, fostering careers in climate resilience.

This study cements UCT's stature, urging investment in SA higher ed to combat climate threats head-on. More details in UCT News article.