Ocean sciences

Mesocosm experiments in different biomes show that future ocean acidification will slow down the dissolution of biogenic silica, decreasing silicic acid availability in the surface ocean and triggering a global decline of diatoms as revealed by Earth system model simulations.

Sustainable mariculture could increase seafood production under almost all climate-change scenarios analysed, but this would require substantial fisheries reforms, continued advances in feed technology and the establishment of effective mariculture governance and best practices.

In situ experiments have demonstrated chemotaxis of marine bacteria and archaea towards specific phytoplankton-derived dissolved organic matter, which leads to microscale partitioning of biogeochemical transformation in the ocean.

Climate forecast systems are used to develop and evaluate global predictions of marine heatwaves (MHWs), highlighting the feasibility of predicting MHWs and providing a foundation for operational MHW forecasts to support climate adaptation and resilience.

Analysis of tide gauge observations shows that, in contrast to the current assumption of stationary storm surge extremes in Europe, the surge contribution to changes in extreme sea levels since 1960 is similar to that of sea-level rise, influencing future coastal planning.

An assessment of the land-to-ocean cycling of carbon through inland waters, estuaries, tidal wetlands and continental shelf waters provides a perspective on the global carbon cycle and identifies key knowledge gaps.

A study uses a temperature-percentile water mass framework to analyse warm-to-cold poleward transport of freshwater in the Earth system, and establishes a constraint to help address biases in climate models.

High-temperature, high-acidity and low-oxygen extremes may pose a particular threat to marine ecosystems, requiring a major effort to understand them and the ability of marine life to respond to them.

New proxy data for ocean pH and an ocean–atmosphere model show that a radically different ocean circulation led to decoupling of ocean productivity and upwelling in the equatorial Pacific Ocean 3–6 million years ago.

Mercury deposition pathways from the atmosphere to the ocean remain uncertain, but mercury stable isotope measurements from the Atlantic and Mediterranean show that ocean uptake of gaseous elemental mercury is more important than previously thought.

Oceanic deposition of wildfire aerosols can enhance marine productivity, as supported here by satellite and in situ profiling floats data showing that emissions from the 2019–2020 Australian wildfires fuelled phytoplankton blooms in the Southern Ocean.

Vermiform microstructure in microbial reefs dating to approximately 890 million years ago resembles the body fossils of Phanerozoic demosponges, and may represent the earliest known physical evidence of animals.

Oceanographic observations from 1970–2018 reveal substantial changes in the summer upper-ocean structure, showing a thickening of the mixed layer and a density gradient increase at its base.

Using a globally coordinated strategic conservation framework to plan an increase in ocean protection through marine protected areas can yield benefits for biodiversity, food provisioning and carbon storage.

The capacity to create an equitable and sustainable ‘blue economy’ from ocean resources will be determined by addressing social conditions, governance and infrastructure, not just resource availability, as shown by a fuzzy logic model incorporating multidisciplinary criteria.

Unexpected intervals of low ²³⁰Th concentration in marine sediment cores are explained by considering that during at least two such periods, the Arctic Ocean and Nordic seas were composed entirely of fresh water and covered by a thick ice shelf.

A tight coupling between metabolic rate, efficacy of oxygen supply and the temperature sensitivities of marine animals predicts a variety of geographical niches that better aligns with the distributions of species than models of either temperature or oxygen alone.

Modelling experiments show that the El Niño response to global warming is self-modulating and depends on its historical variability; if current variability is high, future variability will be low.

Observed global-mean sea-level rise since 1900 is reconciled with estimates based on the contributing processes, revealing budget closure within uncertainties and showing ice-mass loss from glaciers as a dominant contributor.

A linear relationship between the storage of heat and carbon in global oceans in response to anthropogenic emissions is used to reconstruct the effect of circulation changes on past and future ocean warming patterns.

Ocean heatwaves displace surface isotherms by tens to thousands of kilometres—comparable to shifts associated with long-term warming trends—potentially driving rapid redistributions of marine species.

Sea surface density observations in the Arctic Ocean reveal a relationship between the present-day surface water density and the anthropogenic carbon inventory and coincident acidification, suggesting that recent acidification projections are underestimates.

Advanced deep-sea imaging tools yield insights into the structure and function of mucus filtration houses built by midwater giant larvaceans.

Analyses of the recovery of marine populations, habitats and ecosystems following past conservation interventions indicate that substantial recovery of the abundance, structure and function of marine life could be achieved by 2050 if major pressures, including climate change, are mitigated.

Analyses of microbial communities that live 10–750 m below the seafloor at Atlantis Bank, Indian Ocean, provide insights into how these microorganisms survive by coupling energy sources to organic and inorganic carbon resources.

The front of the Getz Ice Shelf in West Antarctica creates an abrupt topographic step that deflects ocean currents, suppressing 70% of the heat delivery to the ice sheet.

A global study of river deltas shows a net increase in delta area by about 54 km² yr⁻¹ over the past 30 years, in part due to deforestation-induced sediment delivery increase.

Satellite-derived analysis of daily vertical migrations of ocean animals shows that the relative abundance and total biomass of these animals differ between different regions globally, depending on the availability of food and necessity to avoid predators.

Since the 1980s, rapid warming of the Indo-Pacific warm pool has altered global rainfall pattern by changing the residence time of the Madden–Julian Oscillation, decreasing it by 3–4 days over the Indian Ocean and increasing it over the Indo-Pacific by 5–6 days.

The authors discuss the potential for sex and gender analysis to foster scientific discovery, improve experimental efficiency and enable social equality.

Nutrient content analyses of marine finfish and current fisheries landings show that fish have the potential to substantially contribute to global food and nutrition security by alleviating micronutrient deficiencies in regions where they are prevalent.

A statistical forecast model using a deep-learning approach produces useful forecasts of El Niño/Southern Oscillation events with lead times of up to one and a half years.

Using phreatic overgrowths on speleothems, sea level during the mid-Piacenzian Warm Period, which was about two to three degrees Celsius warmer than the pre-industrial period, is shown to have been about 16 metres higher than today.

A global dataset of the satellite-tracked movements of pelagic sharks and fishing fleets show that sharks—and, in particular, commercially important species—have limited spatial refuge from fishing effort.

Correction of oddities in the historical record of sea surface temperatures reveals that some basin-wide climate variations were an artefact of systematic biases that stem, in part, from Japanese records being truncated to whole numbers when the records were digitized.

Broadening activation energy distributions and increasing radiocarbon ages reveal the global importance of mineral protection in promoting organic carbon preservation.

Measurements collected during recent polynya events in the Southern Ocean reveal that these sea ice openings formed as a result of weakened stratification and severe storms and were sustained by deep overturning.

Seafloor-derived planktonic foraminifera communities of pre-industrial age are compared with communities from sediment-trap time series and show that Anthropocene communities of a globally distributed zooplankton group differ from their unperturbed pre-industrial state.

This Review discusses particle injection pumps, which inject suspended and sinking particles to different ocean depths and may sequester as much carbon as the biological gravitational pump.

Convergent estimates of nitrogen fixation from an inverse biogeochemical and a prognostic ocean model show that biological carbon export in the ocean is higher than expected and that stabilizing nitrogen-cycle feedbacks are weaker than we thought.

Our knowledge of the distribution and evolution of deep-sea life is limited, impeding our ability to identify priority areas for conservation.

Vertical motions of Earth’s crust had the greatest effect on regional spatial differences in relative sea-level trends along the eastern coast of the USA during 1900–2017, explaining most of the large-scale spatial variance in regional rates of sea-level rise.

Despite inter-model differences in predicting the details of the eastern Pacific El Niño, a robust increase in the corresponding sea surface temperature variability under greenhouse warming is found across models.