Climate Change Effects on Marine Biodiversity

Climate change is reshaping the world’s oceans through rising temperatures, altered chemistry and reduced oxygen levels, with profound consequences for marine organisms and ecosystems. Warming seas drive shifts in species distributions, often prompting warm-water taxa to expand poleward while cold-adapted species contract towards the poles or deeper waters. Ocean acidification, resulting from increased absorption of atmospheric CO₂, impairs calcifying organisms and disrupts food-web interactions. Deoxygenation further restricts the available aerobic habitat, particularly in stratified or slow-circulating regions. Combined, these stressors alter primary production patterns, leading to changes in plankton communities that reverberate through higher trophic levels. Phenological mismatches, such as shifts in breeding or migration timing, undermine ecological synchrony and can reduce reproductive success. Semi-enclosed basins and polar regions, warming faster than the global average, are especially vulnerable to biodiversity loss and ecosystem destabilisation. These changes threaten fisheries yields, coastal protection services and cultural values worldwide. Effective adaptation requires integrated monitoring, predictive modelling and targeted conservation measures, including the establishment of climate-resilient marine protected areas and dynamic management strategies that account for shifting species ranges and habitat suitability.

Research from Nature Portfolio

Recent studies have quantified community-level thermal shifts, revealing that over half of monitored marine assemblages now host an increased proportion of warm-affinity species, a process termed tropicalization, while cold-water species decline in many regions. Research on multiple climate drivers shows that trends in temperature, acidification and deoxygenation are already emerging from natural variability across most of the global ocean, with mitigation measures able to delay these stressors by decades. Investigations into the role of ocean currents have demonstrated that directional agreement between prevailing flows and thermal gradients can either facilitate or hinder species’ range shifts, underscoring the importance of incorporating abiotic dispersal forces into forecasts of biogeographical change.

Climate Change Effects on Marine Biodiversity publication trend

The graph below shows the total number of articles in climate change effects on marine biodiversity across all publications each year (not limited to Nature Index journals).

Technical terms

Community Temperature Index: metric of the mean thermal affinity of species within a community.

Tropicalization: process by which warm-water species increase in abundance in response to warming.

Deborealization: decline of cold-water species in marine communities under climate warming.

Representative Concentration Pathway: standardised greenhouse gas emission scenarios used to project future climates.

Species Distribution Model: statistical tool that predicts habitat suitability based on environmental variables.

Metabolic Index: ratio of oxygen supply to demand that delineates suitable aerobic habitat for marine species.

References

1. Cross-basin and cross-taxa patterns of marine community tropicalization and deborealization in warming European seas. Nature Communications (2024).
2. Climate change disrupts core habitats of marine species. Global Change Biology (2023).
3. Fish and tips: Historical and projected changes in commercial fish species' habitat suitability in the Southern Hemisphere. The Science of The Total Environment (2024).
4. Simulated Abrupt Shifts in Aerobic Habitats of Marine Species in the Past, Present, and Future. Earth's Future (2024).
5. Responses of Marine Organisms to Climate Change across Oceans. Frontiers in Marine Science (2016).
6. Rapid emergence of climate change in environmental drivers of marine ecosystems. Nature Communications (2017).
7. Ocean currents modify the coupling between climate change and biogeographical shifts. Scientific Reports (2017).