Climate-driven shifts in species diversity, community composition and phenology can disrupt ecosystem functioning and compromise marine ecosystem stability. The Mediterranean Sea, a global biodiversity hotspot, is particularly vulnerable to anthropogenic climate change and is experiencing a growing biodiversity crisis especially driven by warming, habitat degradation, pollution and the introduction of new species. Yet, current knowledge of biodiversity changes in this region is largely limited to shallow shelf benthic communities and macroorganisms. Calcifying phytoplankton and zooplankton, however, offer a unique lens into pelagic ecosystem dynamics, as their fossil record preserves signals of biodiversity change in deep-sea sediments spanning the Industrial Era and the current phase of rapid warming. This study focuses on the reconstruction of diversity change of two dominant calcifying plankton groups: coccolithophores and foraminifera (primary and secondary producers). We examine two selected sedimentary records of the western and central Mediterranean-Alboran Sea and the Strait of Sicily-spanning the last similar to 1700 and 200 years of modern climate, respectively. By quantifying abundance, diversity and turnover of species composition we evaluate the potential response of calcifying plankton assemblages to oceanographic changes under anthropogenic climate change. The results revealed contrasting changes in the diversity of the two dominant calcifying plankton groups, with a rapid increase in coccolithophore diversity alongside a decrease in planktonic foraminiferal diversity during the Industrial Era. We attribute these group-specific responses to ecological and physiological differences, particularly in relation to life cycles and water column distribution, under increasingly stratified, nutrient-depleted surface waters driven by rising sea surface temperatures. In addition, this study provides first indication of tropicalization of the western Mediterranean plankton derived from the increasing intrusion and eastward expansion of the coccolithophore Gephyrocapsa oceanica from the Strait of Gibraltar into the Mediterranean Sea. The highest abundances of this species are restricted to the Equatorial Atlantic Divergence Zone and only found in higher proportions in the Mediterranean during past warm periods. Although the temperate-productivity foraminiferal species of Globigerina bulloides and Globorotalia inflata remain the dominant foraminiferal species, previous minor dominant species are being replaced by warm-oligotrophic species, such as Trilobatus sacculifer and Globigerinella spp. These align with model projections of tropical species migrating into the area, previously documented among benthic organisms and point to a broader restructuring of planktonic life.

Planktonic foraminifera (PF) shells are ubiquitous archives used as proxies in paleoceanography and play a crucial role in paleoclimate reconstructions. Species respond differently to abiotic and biotic factors and have shifted habitats with recent ocean warming. We re-evaluate the biogeographic limits of major PF species in the modern ocean, using the FORCIS data to extend the data coverage and explore potentially overlooked distributions of (small) species from the seminal works from the 1950s to the 1970s that were based on > 200 µm mesh-size plankton tows. We present a comprehensive update of their modern biogeography, vertical habitat distribution, and thermal tolerance using the FORCIS database, which includes all available water-column-sourced data from the last century. Our analysis confirms that the higher PF diversity is in the tropical and subtropical oceans. PF are observed in temperatures ranging from −2 to 31 °C, highlighting their remarkable thermal tolerance and/or adaptability to a wide range of temperatures. In addition, species that displayed a preferential habitat in lower latitudes in the 1950-to-1970 time interval (e.g. G. ruber) have been observed at higher latitudes over the last 50 years. Since the 1970s, medium-sized species have increased in abundance across all latitudes, from the tropical to polar oceans, a trend particularly evident in the extensive data from the eastern North Atlantic. The analysis of the FORCIS database updates the evolving biogeography of modern PF and advances our understanding of their ecology, providing revised benchmarks for paleoceanographic interpretations and the ecology of modern planktonic calcifiers.

The cycling of calcium carbonate (CaCO3) in the ocean is closely linked to seawater alkalinity and the regulation of atmospheric CO2. In the modern pelagic ocean, almost all CaCO3 is produced by three groups of calcifying planktonic organisms: coccolithophores, foraminifers, and shelled pteropods. In this Review, we examine the differences in functional traits that define each group's distinctive role in the global carbon cycle and their sensitivity to climate change and ocean acidification. This synthesis reveals that a single representation of CaCO3 in climate models is unlikely to accurately reflect system dynamics or their impacts on biogeochemical cycling under climate change. We argue that understanding past and future CaCO3 cycle requires a better delineation of the traits that make up the diversity of calcifying plankton groups.

Planktonic foraminifera are key contributors to the oceanic carbon cycle. In pelagic environments, carbonate production by planktonic biomineralizers regulates ocean-atmosphere carbon dioxide exchange and exports surface carbon to the deep ocean. Here we compare shell traits of three planktonic foraminifera species from the central Atlantic with a suite of environmental parameters to discern the factors underlying their variations. Our analysis revealed that calcification in foraminifera is associated with seawater density and depends on species habitat depth, whereas foraminifera bulk shell densities may serve as a seawater density proxy, regardless of species. We observe that their shell weights increased with habitat depth, enabling the living cells to adjust their overall density to match that of the surrounding liquid. This suggests that calcification in nonmotile organisms has a buoyancy regulatory function and will respond to the anthropogenically driven reductions in ocean density (oceanic rarefication), with potential consequences for the carbon cycle.

Rising carbon dioxide emissions are provoking ocean warming and acidification1,2, altering plankton habitats and threatening calcifying organisms3, such as the planktonic foraminifera (PF). Whether the PF can cope with these unprecedented rates of environmental change, through lateral migrations and vertical displacements, is unresolved. Here we show, using data collected over the course of a century as FORCIS4 global census counts, that the PF are displaying evident poleward migratory behaviours, increasing their diversity at mid- to high latitudes and, for some species, descending in the water column. Overall foraminiferal abundances have decreased by 24.2 ± 0.1% over the past eight decades. Beyond lateral migrations5, our study has uncovered intricate vertical migration patterns among foraminiferal species, presenting a nuanced understanding of their adaptive strategies. In the temperature and calcite saturation states projected for 2050 and 2100, low-latitude foraminiferal species will face physicochemical environments that surpass their current ecological tolerances. These species may replace higher-latitude species through poleward shifts, which would reduce low-latitude foraminiferal diversity. Our insights into the adaptation of foraminifera during the Anthropocene suggest that migration will not be enough to ensure survival. This underscores the urgent need for us to understand how the interplay of climate change, ocean acidification and other stressors will impact the survivability of large parts of the marine realm.

Planktonic Foraminifera have been collected from the water column with different plankton sampling devices equipped with nets of various mesh sizes, which impedes direct comparison of observed quantifications. Here, we use data on the community size structure of planktonic Foraminifera to assess the impact of mesh size on the measured abundance (ind m−3) of planktonic Foraminifera. We use data from the FORCIS database (Chaabane et al., 2023, Scientific Data 10: 354) on the global ocean at different sampling depths over the past century. We find a global cumulative increase in abundance with size, which is best described using a Michaelis–Menten function. This function yields multiplication factors by which one size fraction can be normalized to any other size fraction equal to or larger than 100 μm. The resulting size normalization model is calibrated over a range of different depth intervals, and validated with an independent dataset from various depth ranges. The comparison to Berger's (1969, Deep. Res. Oceanogr. Abstr. 16: 1–24) equivalent catch approach shows a significant increase in the predictive skill of the model. The new size normalization scheme enables comparison of Foraminifera abundance data sampled with plankton nets of different mesh sizes, such as compiled in the FORCIS database. The correction methodology may be effectively employed for various other plankton groups such as diatoms and dinoflagellates.

Planktonic Foraminifera are unique paleo-environmental indicators through their excellent fossil record in ocean sediments. Their distribution and diversity are affected by different environmental factors including anthropogenically forced ocean and climate change. Until now, historical changes in their distribution have not been fully assessed at the global scale. Here we present the FORCIS (Foraminifera Response to Climatic Stress) database on foraminiferal species diversity and distribution in the global ocean from 1910 until 2018 including published and unpublished data. The FORCIS database includes data collected using plankton tows, continuous plankton recorder, sediment traps and plankton pump, and contains ~22,000, ~157,000, ~9,000, ~400 subsamples, respectively (one single plankton aliquot collected within a depth range, time interval, size fraction range, at a single location) from each category. Our database provides a perspective of the distribution patterns of planktonic Foraminifera in the global ocean on large spatial (regional to basin scale, and at the vertical scale), and temporal (seasonal to interdecadal) scales over the past century.

Climate change manifests differently around the world, with geographical location and biophysical characteristics shaping the impacts felt in a particular region. People with a long history of interaction with the environment can differentiate with precision and detail climate change impacts occurring in their social-ecological systems. This chapter draws on the knowledge of local communities of Sierra Nevada, a mountainous area of Spain, to study climate-related cascading effects. It includes data from 238 surveys, in which respondents were asked to identify the most impactful changes in the atmospheric, physical, biological, and human systems. It uses network analysis (1) to identify the triggering climate change impacts and (2) to analyse their cascading effects. Results show that informants devoted to agricultural and livestock activities perceive more triggering and cascading impacts on their social-ecological system and more relations between them than informants not devoted exclusively to these activities. Results show that elements of the atmospheric and the physical systems trigger most cascading effects, whereas elements of the biological and the human system are the most impacted.

The efficacy of global environmental assessments in informing and shaping ocean and coastal management is hampered by recognized gaps in global science endeavours. In order to bridge these gaps, and secure inclusive and equitable knowledge co-construction by ocean stakeholders, the International Panel for Ocean Sustainability (IPOS) is emerging. Here we present the outcomes of the "Bridging Shades of Blue Workshop" held in Spain 2023. A diverse group of Ocean knowledge holders, including policymakers, small-scale fishers, marine social scientists and ocean lawyers gathered to reflect on the key features, challenges, strategies, actors to be involved, as well as pathways to balance power for advancing an inclusive and equitable IPOS. As a result, six foundational dimensions of IPOS's institutional identity were proposed as IPOS ID cards: 1) Diversifying Ocean Knowledge Systems, 2) Widening the Range of Methods for Ocean Knowledge Production, 3) Informing Decision-making, 4) Engaging at the Interfaces of Knowledge with Decision-making, 5) Communicating, Learning, and Sharing Knowledge, 6) Measuring Progress and Evaluating Success. We conclude by emphasizing IPOS's potential role as a beacon for inclusive, equitable, and sustainable ocean governance.

Anthropogenic activities, in particular rising CO2 emissions, provoke ocean warming and acidification1,2, altering plankton habitats and threatening calcifying species3,4 such as planktonic Foraminifera (PF). Whether they can cope with these unprecedented rates of environmental change, through lateral migrations and vertical displacements, is unresolved. Here we show, using over a century of data from the FORCIS5 global census counts, that PF display evident poleward migratory behaviours, increasing their diversity at mid to high latitudes, and for some symbiont-barren species descending in the water column. Global PF abundance decreased by 24.24±0.11% over the last decades. Beyond lateral migrations6, our study uncovers intricate vertical migration patterns among PF species, presenting a nuanced understanding of their adaptive strategies. In projected temperature and carbonate saturation states for 2050 and 2100, low-latitude PF species will face physico-chemical environments that surpass their current tolerance. While these species might replace high-latitude ones through poleward shifts, this would radically alter low-latitude ecosystems. Our insights of PF adaptation during the Anthropocene reveals that 'migration is not enough', and has broader implications for the evolution of marine biodiversity under multiple stressors.

Tehran is one of the most polluted cities in the world with 48 days of air pollution exceeding the admissible threshold (AQI > 150) for 3 months of the 15 years studied. This period coincides with the time when Tehran’s inversion reaches its maximum stability. The purpose of this study was to determine the height of air pollution in Tehran in the days when pollution exceeds the permissible limit. Continuing to study the pressure and temperature conditions of these days, we then considered the geographical and topographic conditions, and finally identified the best of these cells for potential theoretical air turbulence. The results of this study, based on the Harmonic Analysis method and based on Tehran temperature and pressure data over a 15-year period (2003–2017), show that the highest elevation of Tehran inversion does not exceed 1800 m on polluted days. Only within 6 days of those beyond the admissible threshold, temperature and pressure cells with the highest Newtonian mass are formed. The center of these cells formed with a compressive difference of 32 mg in November, 7 mg in January, 11 mg in December, and temperature difference of 1.1° in November, 4.4° in January, and 1.9° in December. Generally, we considered the formed cells by the temperature and pressure difference and the gradient between them, as well as the difference in height between the cells and their location. This information, combined with the local winds causing the differences in temperature and pressure, allows us to elucidate conditions for creating air turbulence in Tehran and mitigating the amount and degree of air pollution.

The inter-ocean transfer of warm and salty water through the Agulhas leakage is regarded as a significant factor influencing the South Atlantic's surface and intermediate water hydrography. To evaluate the extension of Agulhas leakage for the past 1.2 Ma, planktonic foraminiferal assemblage from Ocean Drilling Program Hole 1088B, within the vicinity of AL, and Hole 1090B, located south of the significant Agulhas retroflection region, were generated. The Hole 1088B shows higher abundance of tropical and sub-tropical assemblage. The com-bination of Globigerinoides ruber, Trilobatus sacculifer, Globigerinoides conglobatus and Globorotalia menardii has previously been defined as the Agulhas leakage fauna [ALF]. The pulse-like amplification of the ALF record at major glacial-interglacial transitions indicates these were periods of strengthened Agulhas leakage with subse-quent shedding of Agulhas rings and filaments as far as-41 degrees S. From-450 ka, the frontal zone exhibits strong ALF variations with evident increase at glacial-interglacial transitions of Marine Isotopic Stages (MIS) 12, 10, 8 and 6, suggesting vigorous eddy mixing and a shift in the leakage zone towards the subantarctic waters. The migration of the Subtropical Convergence and Neogloboquadrina pachyderma (s) coiling ratios during these glacial-interglacial transitions supports the southward expansion of Agulhas leakage. The ALF record is sup-ported by the delta 18O record of Globigerina bulloides from hole 1088B, which identify a major anomaly at MIS 10, with depleted delta 18O values towards the glacial termination. Simultaneously, the results from Hole 1090B show restricted presence of tropical-subtropical assemblage with their appearance reported only at glacial-interglacial transitions of the MIS 16, 12, 10 and 8. The curtailed ALF index and dominance of the subpolar species N. pachyderma (s) indicate the termination of Agulhas leakage before reaching the Subantarctic zone. The ODP sites chosen for the study reveal the intensification of Agulhas leakage and southward shift of the major leakage zone into the subantarctic zone during the Pleistocene glacial-interglacial transitions.

The mass of well-preserved calcite in planktonic foraminifera shells provides an indication of the calcification potential of the surface ocean. Here we report the shell weight of 8 different abundant planktonic foraminifera species from a set of core-top sediments along the Mid-Atlantic Ridge. The analyses showed that near the equator, foraminifera shells of equivalent size weigh on average 1/3 less than those from the middle latitudes. The carbonate preservation state of the samples was assessed by high resolution X-ray microcomputed tomographic analyses of Globigerinoides ruber and Globorotalia truncatulinoides specimens. The specimen preservation was deemed good and does not overall explain the observed shell mass variations. However, G. ruber shell weights might be to some extent compromised by residual fine debris internal contamination. Deep dwelling species possess heavier tests than their surface-dwelling counterparts, suggesting that the weight of the foraminifera shells changes as a function of the depth habitat. Ambient seawater carbonate chemistry of declining carbonate ion concentration with depth cannot account for this interspecies difference. The results suggest a depth regulating function for plankton calcification, which is not dictated by water column acidity.

While we know that climate change is having different impacts on various ecosystems and regions of the world, we know less how the perception of such impacts varies within a population. In this study, we examine patterns of individual variation in climate change impacts reports using data from a sample (n = 238) drawn from 33 mountainous municipalities of Sierra Nevada, Spain. Sierra Nevada inhabitants report multiple climate change impacts, being the most frequently reported changes in snowfall and snow cover, abundance of terrestrial fauna, freshwater availability, and extreme temperatures. Reports of climate change impacts vary according to informants' sociodemographic characteristics and geographical location. People with life-long bonds with the environment and higher connection and dependence upon ecosystem services report more climate change impacts than other informants, as do people with lower level of schooling. We also found that reports of climate change impacts vary according to geographic areas, which reinforces the idea that climate change generates differentiated impacts even at small geographical scales. Understanding intracultural variation in reports of climate change impacts not only gives an enriched picture of the human dimensions of climate change but might also help design more targeted mitigation and adaptation responses.

Planktonic Foraminifera are ubiquitous marine protozoa inhabiting the upper ocean. During life, they secrete calcareous shells, which accumulate in marine sediments, providing a geological record of past spatial and temporal changes in their community structure. As a result, they provide the opportunity to analyze both current and historical patterns of species distribution and community turnover in this plankton group on a global scale. The FORCIS project aims to unlock this potential by synthesizing a comprehensive global database of abundance and diversity observations of living planktonic Foraminifera in the upper ocean over more than 100 years starting from 1910. The database will allow for unravelling the impact of multiple global-change stressors acting on planktonic Foraminifera in historical times, using an approach that combines statistical analysis of temporal diversity changes in response to environmental changes with numerical modeling of species response based on their ecological traits.

Abstract. High resolution climate model simulations for the last millennium were used to elucidate the main winter Northern Hemisphere atmospheric pattern during enhanced Eastern Mediterranean Transient (EMT-type) events, a situation in which an additional overturning cell is detected in the Mediterranean at the Aegean Sea. The differential upward heat flux between the Aegean Basin and the Gulf of Lions was taken as a proxy of EMT-type events and correlated with winter mean geopotential height at 500 mb in the Northern Hemisphere (200 N-900 N and 1000 W-800 E). Correlations revealed a pattern similar to the Eastern Atlantic/Western Russian (EA/WR) mode as the main driver of EMT-type events, with the past 1000 yr of EA/WR-like mode simulations being enhanced during insolation minima. Our model results are consistent with alkenone Sea Surface Temperature (SST) reconstructions that documented an increase in the west-east basin gradients during EMT-type events.

The modern Eastern Equatorial Pacific (EEP) Ocean is a high nutrient low chlorophyll (HNLC) upwelling region and a large oceanic source of carbon to the atmosphere. During the last deglaciation, the EEP played a major role in the outgassing of carbon dioxide into the atmosphere from the upwelling surface water system of CO2-enriched deep-water masses originating from the Southern Ocean. The EEP up-welling system is also fertilizing the surface waters and enhancing the biological pump. Here we present data on the mass and calcification dynamics of the coccolithophore species Emiliania huxleyi spanning the last 30 ky at Site ODP 1238 (1 degrees 52.310'S, 82 degrees 46.934'W; 2203 m) in the EEP. Our results show an increased coccolith calcification degree during times of high pCO(2) and low surface water pH conditions; this unexpected result is tentatively explained as related to changes in homeostasis equilibrium at the site of calcification and between the cell and the seawater environment. We estimated the E. huxleyi particulate inorganic to organic carbon ratio (PIC:POC) in order to detect changes in the carbonate counter-pump to carbon pump activity, which can act as either a positive or negative feedback to atmospheric CO2 modulating air-sea gas exchange. Our study indicates an enhanced coccolithophore biological pump during the last glacial that could have buffered, at least partially, the excess of pCO(2atm) via absorption into the ocean. Finally, during the last deglaciation, the enhanced carbonate counter pump was a major source of high pCO(2sw) in the EEP surface ocean. (C) 2021 Elsevier Ltd. All rights reserved.

West Nile Virus (WNV) has recently emerged as a major public health concern in Europe; its recent expansion also coincided with some remarkable socio-economic and environmental changes, including an economic crisis and some of the warmest temperatures on record. Here we empirically investigate the drivers of this phenomenon at a European wide scale by constructing and analyzing a unique spatial–temporal data-set, that includes data on climate, land-use, the economy, and government spending on environmental related sectors. Drivers and risk factors of WNV were identified by building a conceptual framework, and relationships were tested using a Generalized Additive Model (GAM), which could capture complex non-linear relationships and also account for spatial and temporal auto-correlation. Some of the key risk factors identified in our conceptual framework, such as a higher percentage of wetlands and arable land, climate factors (higher summer rainfall and higher summer temperatures) were positive predictors of WNV infections. Interestingly, winter temperatures of between 2°C and 6°C were among some of the strongest predictors of annual WNV infections; one possible explanation for this result is that successful overwintering of infected adult mosquitoes (likely Culex pipiens) is key to the intensity of outbreaks for a given year. Furthermore, lower surface water extent over the summer is also associated with more intense outbreaks, suggesting that drought, which is known to induce positive changes in WNV prevalence in mosquitoes, is also contributing to the upward trend in WNV cases in affected regions. Our indicators representing the economic crisis were also strong predictors of WNV infections, suggesting there is an association between austerity and cuts to key sectors, which could have benefited vector species and the virus during this crucial period. These results, taken in the context of recent winter warming due to climate change, and more frequent droughts, may offer an explanation of why the virus has become so prevalent in Europe.