Marine Heatwaves and Ecosystem Dynamics

Marine heatwaves are prolonged periods of anomalously high ocean temperatures that can disrupt physical, chemical and biological processes across multiple marine habitats. Traditionally monitored via sea surface temperature, these events now attract growing attention for their vertical and benthic manifestations, which may differ in intensity, duration and ecological impact from surface warming. Drivers span large-scale climate modes, such as El Niño–Southern Oscillation and the Pacific Decadal Oscillation, as well as local atmospheric and oceanographic factors including wind patterns, stratification and heat flux variability. Acute consequences include shifts in species distributions, mass mortality events in coral reefs and kelp forests, and altered trophic interactions. Chronic or recurrent heatwaves can undermine ecosystem resilience, reduce fisheries yields and compromise carbon sequestration services. Emerging research emphasises the interdependence between physical drivers and biological responses, highlighting the need for integrated monitoring across depth strata to anticipate ecosystem thresholds, inform adaptive management and safeguard social and economic livelihoods.

Research from Nature Portfolio

Recent studies have extended the characterisation of marine heatwaves beyond the surface layer. High-resolution ocean reanalyses along North American continental shelves reveal that bottom marine heatwaves may exhibit greater intensity and persistence than their surface counterparts, with distinct depth-dependent variability and occasional decoupling from surface warming. Complementary four-dimensional analyses of global ocean reanalyses demonstrate that nearly one third of heatwave events reside entirely in subsurface layers, undetectable by surface temperature alone, and that such subsurface events have markedly increased in frequency over recent decades. Together, these findings underscore the necessity of vertically resolved observations and models to capture the full spatial extent of thermal extremes and anticipate their ecological ramifications.

Marine Heatwaves and Ecosystem Dynamics publication trend

The graph below shows the total number of articles in marine heatwaves and ecosystem dynamics across all publications each year (not limited to Nature Index journals).

Technical terms

Marine heatwave: Period of anomalously high ocean temperatures sustained over days to months.

Bottom marine heatwave: Subsurface warming event affecting temperatures at or near the sea floor.

Epipelagic zone: Upper ocean layer extending from the surface to ~200 m depth, where sunlight supports photosynthesis.

Compound event: Co-occurrence of multiple moderate or extreme anomalies in temperature, productivity or oxygen that together exacerbate impacts.

Net primary productivity: Rate of organic carbon production by photosynthetic organisms after accounting for respiration losses.

References

1. Bottom marine heatwaves along the continental shelves of North America. Nature Communications (2023).
2. Frequent marine heatwaves hidden below the surface of the global ocean. Nature Geoscience (2023).
3. Extreme and compound ocean events are key drivers of projected low pelagic fish biomass. Global Change Biology (2023).
4. Projected Marine Heatwaves in the 21st Century and the Potential for Ecological Impact. Frontiers in Marine Science (2019).
5. Future evolution of Marine Heatwaves in the Mediterranean Sea. Climate Dynamics (2019).