Abstract. Regime dependencies and Granger causal relationships between tropical and extratropical teleconnections are inferred using Bayesian structure learning. Using ERA5 data, an examination of the differences between the learned graphical structures during particular phases of the Interdecadal Pacific Oscillation (IPO) are used to infer the role of the background state on interactions between the major climate teleconnections. These relationships present a clear regime dependency on the phase of IPO. In the positive phase, IPO autocorrelations are weak whereas Indian Ocean Dipole (IOD) and El Niño Southern Oscillation (ENSO) autocorrelations and the influence of the Madden Julian Oscillation (MJO) are indicative of an enhanced Walker circulation. In contrast, during the negative phase, IPO autocorrelations are strongest with evidence of an enhanced role for extratropical teleconnections on the tropics. Exclusion of MJO removes important tropical-extratropical influences while increasing posterior edge weights between ENSO, the IPO and IOD. Our analysis reveals the dependence of the ENSO autocorrelation on the phase of the background IPO state, and the role of the MJO as being key to link the extratropical tropospheric modes Pacific North American and North Atlantic Oscillation (PNA, NAO) and equatorial surface ocean temperatures (IOD, ENSO) and as a consequence convection.

Context The white shark (Carcharodon carcharias) is a large, highly migratory, apex predator typically found in coastal, continental shelf and pelagic environments of temperate and subtropical waters worldwide. In the western North Atlantic (WNA), white sharks have been studied for decades through catch data and other observations along the US Atlantic coast. Aims Beginning in 2012, OCEARCH has coordinated a comprehensive, long-term study of this population that includes tagging sharks with satellite-linked and acoustic tags to track their movements, understand their life history, and map their critical habitats. Methods Tagging occurred between Nova Scotia, Canada, and Jacksonville, Florida, USA, on the Atlantic coast. Four life stages (young-of-the-year, juvenile, subadult, adult) were tagged, showing the migratory cycles of this WNA population from age zero through maturity. Key results A combination of satellite-linked and acoustic tags showed all four life stages enter the Gulf of Mexico (GoM) through the Straits of Florida and use this habitat primarily during the overwintering period. Of 92 white sharks tagged, 57 (62.0%) showed activity in the GoM or the Straits of Florida, spending most of their time (91.2%) in epipelagic waters and moving mainly from the Florida Keys north along the outer West Florida Shelf. Specific areas of extensive habitat use and evidence of philopatry were identified, particularly in the Pulley Ridge area off south-western Florida. Some animals crossed into the western GoM and into Mexican coastal waters; movements along the northern coast of Cuba were also noted. Conclusions These tagging results clearly demonstrated the importance of this region as an overwintering habitat for white sharks, particularly in shelf edge waters of the eastern GoM, and indicated a more widespread and persistent use of the GoM by this recovering species than previously known. Implications Our results demonstrated the wide-ranging nature of the WNA white shark population and the faunal connectivity between Atlantic Canada and the GoM, including territorial waters of other nations. Continued monitoring of this population, fine-scale analysis of movements in critical habitats, and further research on the drivers of migration are needed for science-based policy to conserve this vulnerable species.

Tropical easterly waves in the North Atlantic basin and their precipitating moisture sources: Insights from a downscaled climatological analysis

High-resolution stalagmite records from Southwest China reveal a North Atlantic link to the 8.2 ka event

Lithologic facies and stratigraphic evolution of North Atlantic seagrass beds reveal centennial-scale resilience to burial events

Abstract In this study, the impact of Atlantic Multidecadal Oscillation (AMO) on the connection of winter sea-ice concentration (SIC) over Barents-Kara Seas (BKS) to El Niño-Southern Oscillation (ENSO) is explored. It is found that the interannual connection is strengthened during the positive AMO phase (AMO+), but weakened during the negative AMO phase (AMO–). During AMO+, poleward heat and moisture transports associated with La Niña toward BKS are enhanced to cause a strong sea-ice decline via the combination of increased Ural blocking and the intensified positive phase of North Atlantic Oscillation (NAO) due to enhanced and widened Atlantic Hadley cell. Reversed results are detected during El Niño because the negative NAO and Ural trough emerge. However, the BKS SIC-ENSO connection is less evident because interannual changes in poleward atmospheric transports between La Niña and El Niño are reduced during AMO–. These results suggest that the impact of ENSO on the winter BKS SIC strongly depends on the phase of AMO.

Abstract Tropical cyclones (TCs) and their post-tropical (PTC) counterparts respond differently to surface warming, reflecting distinct thermodynamic and dynamical controls on storm structure and heavy precipitation. To quantify these responses, we developed a dynamically derived wind-based radius (r6) using ERA5 near-surface winds, capturing storm size, heavy precipitation metrics, and translation speed for North Atlantic tropical cyclones from 2001 to 2024. This metric provides a physically consistent framework to characterize storm evolution and track how heavy precipitation responds to warming. During the TC phase, precipitation intensity rises sharply with all temperatures, reaching a median of 21%/K for dewpoint, while the area of heavy precipitation expands by up to a median of 12.5%/K. Overall cyclone size generally contracts, with a median of 6.5%/K for air temperature, although this contraction weakens or reverses at very high sea-surface temperatures, particularly in the Caribbean, producing unusually large, long-lived storms. Slower motion in these warmer, low-latitude regions prolongs precipitation, boosting totals and concentrating heavy precipitation near the storm core. In contrast, PTCs expand but show limited thermodynamic sensitivity, producing broader, asymmetric precipitation fields under faster translation. These results show rapid ocean warming can intensify and prolong TC precipitation, amplifying regional risks in the North Atlantic.

Anthropogenic pressures have increased the emergence and spread of infectious disease in wildlife in recent decades, with cascading impacts on ecosystem dynamics and elevated risk to public health. Understanding factors that contribute to disease severity, and population- and community-level impacts, is critical to predict and mitigate infectious disease outbreaks. We aimed to investigate how host genetic factors contribute to harbor seal susceptibility to phocine distemper virus (PDV), a virus that has caused variable levels of mortality among pinniped populations across the North Atlantic. We conducted whole-genome sequencing of harbor seals that were stranded during and following a PDV outbreak that occurred in the Northeast United States in 2018 and used genome-wide association and FST-based approaches to identify genetic variants putatively associated with survival. A subset of harbor seals (10 cases, 10 controls) was sequenced at high coverage (~58x) to generate a reference haplotype panel and impute genotypes in remaining samples (37 cases, 45 controls) that were sequenced at a lower coverage (~4x). Upon investigation of 148 644 filtered single nucleotide polymorphisms (SNPs), we identified 33 candidate genes related to innate and adaptive immunity and 37 genes related to the nervous system that were associated with harbor seal survival. These results provide further evidence for the importance of immunogenetic variation and highlight additional key pathways and biological processes that may confer resistance to PDV. Genome-wide approaches, which can reveal the complexity of genetic variation underpinning disease-associated traits, are critical tools to help us understand and potentially predict the impact of future disease outbreaks.

Climate oscillations such as the El Niño-Southern Oscillation (ENSO), Indian Ocean Dipole (IOD) and North Atlantic Oscillation (NAO) significantly influence global weather variability, posing challenges to agricultural productivity and food security. Their impacts−ranging from altered rainfall patterns to temperature extremes−disrupt crop growth, especially in rainfed systems. Understanding these oscillations is vital for enhancing yield prediction and informing adaptive agricultural planning. This review synthesizes mechanistic insights and empirical findings from peer-reviewed literature on the influence of ENSO, IOD and NAO on crop yields across major agro-climatic zones. It also evaluates predictive tools, including statistical models, dynamic crop simulations and AI-driven forecasting systems. Crop-specific vulnerabilities and regional disparities in oscillation impacts were systematically analyzed to assess adaptation needs. Findings reveal that ENSO, IOD and NAO generate region-specific yield anomalies by modulating soil moisture, evapotranspiration and phenological development. Crops such as rice, maize and wheat exhibit heightened sensitivity during key growth stages under oscillation-driven stressors. Modern forecasting models incorporating oscillation indices improve predictive accuracy and provide early warnings for yield variability. However, gaps remain in translating forecasts into actionable farm-level decisions, especially in resource-limited regions. To build agricultural resilience, integrating oscillation-based forecasts into local advisory services, promoting climate-smart practices and adopting inclusive, region-specific adaptation strategies are essential. Bridging science-policy gaps and strengthening climate services will support anticipatory planning and safeguard food systems under increasing climate variability.

Decadal synchronization between the Gulf Stream and Kuroshio currents has recently been reported. Given the large-scale coupled variability of western boundary currents and extensions (WBCEs), further investigation into its seasonality, predictability, and potential future changes is needed. Observations and high-resolution climate simulations reveal distinctive covariance between North Pacific and North Atlantic WBCE sea surface temperatures during boreal summer, possibly linked to preceding Arctic sea-ice variability. Model simulations suggest that cold-season Greenland and Barents Sea ice loss enhances anomalous planetary-scale atmospheric waves and meridional jet shifts, contributing to summertime WBCE temperature anomalies. Although we show that summer WBCE covariability arises from intrinsic variability, future climate projections and targeted model experiments imply that this internal coupled variability may be modulated by radiatively forced changes. Our findings suggest that summer WBCE covariability has increased in the historical record but may weaken in response to future reductions in Arctic sea ice under higher radiative forcing.

The Quaternary Period (the last 2.58 Ma) was characterized by the waxing and waning of large ice sheets in the Northern Hemisphere. Using sediment sequences from the Iberian Margin, we demonstrate that expansion of Northern Hemisphere ice sheets around 2.7 Ma was accompanied by the emergence of millennial climate variability (MCV) during glacial periods. The onset of MCV at ~2.7 Ma was heralded by isolated precursor events, followed by multiple millennial climate oscillations at ~2.5 Ma. These events coincided with deposition of ice-rafted detritus in the North Atlantic, suggesting a role for marine-terminating ice sheets. Once established, MCV became an intrinsic feature of glacial climates of the Quaternary. Our findings underscore the profound impact Northern Hemisphere glaciation had on climate variability across multiple time scales.

We present a comprehensive dataset of dayside auroral emissions observed by the Global-scale Observations of the Limb and Disk (GOLD) mission from October 2018 to June 2025. The dataset contains over 47,000 unique scans of the northern aurora in three far-ultraviolet spectral channels (OI 135.6 nm, NI 149.3 nm, and N₂ LBH), estimates of the background dayglow, binary masks of auroral locations, and other corresponding spatial and temporal metadata. The OI 135.6 nm, NI 149.3 nm, and N₂ LBH emissions are far-ultraviolet signatures of electron-impact excitation in the upper atmosphere and therefore serve as tracers of auroral electron precipitation. From this dataset, auroral pixels are directly available with no dayglow contamination of the emissions. Auroral signals are extracted through a multi-stage processing pipeline inspired by computer vision and machine learning techniques. This dataset provides a consistent view of the dayside aurora over the North American and Atlantic sectors, enabling studies of auroral dynamics with GOLD observations.

Marine heatwaves have become more frequent and intense under anthropogenic warming, posing increasing threats to marine ecosystems and coastal societies, necessitating a better understanding of their mechanism and predictability. Here we show how ocean dynamics modulate marine heatwaves globally by comparing dynamic and slab ocean climate model simulations. We discover that ocean dynamics significantly promote marine heatwave intensity and duration in mid-to-high latitude oceans, as well as the eastern tropical Pacific where marine heatwaves are inherently linked to extreme El Niño events. Our mixed-layer heat budget analysis unravels that heat accumulation during marine heatwave episodes is strongly influenced by vertical mixing and horizontal transport processes, so that warm sea surface temperature extremes in dynamic ocean differ in magnitude and evolution rhythm from those in slab ocean. We further find robust multi-year potential predictability of marine heatwave in the North Atlantic with a dynamic ocean, owing primarily to the predictability of the Atlantic Meridional Overturning Circulation. Our findings emphasize the irreplaceable role of oceanic dynamics in marine heatwave evolution and predictability, with important implications for future climate extreme prediction and adaptation strategies.

The article is a continuation of systematic studies of marine ostracods of South Africa. The synonymies of the species Aurila dayii (Aurila strongyle “syn. nov.”) and Aurila petricola (Hemicythere? sp. “syn. nov.”) are proposed. For the first time, diagnostic characters of the species Hemicythere californiensis, Aurila petricola, Aurila kliei, and Mutilus bensonmaddocksorum have been identified. The presence/absence of the diagnostic “Aurila-Tooth” and its variability in the species Aurila dayii and Aurila petricola are discussed. SEM/DM images of generic and specific taxonomic characters are given. For the first time, sexual dimorphism of the shell was identified for the species Hemicythere californiensis and Urocythereis arcana, and supplemented for Aurila dayii, A. petricola, A. kliei, Mutilus bensonmaddocksorum, and M. malloryi. North Atlantic, North Pacific, and endemic zoogeographical groups of ostracods were identified, and it was concluded that endemics (70% of the total number of described species) dominate the biotopes of the southern and eastern coasts of South Africa. Data on the ecology, stratigraphic position, and geographical distribution of South African ostracods have been supplemented. Conclusions were made regarding the varying degrees of study of ostracods of the genera Hemicythere, Aurila, Mutilus, Urocythereis, and the need for further study of intraspecific variability, sexual dimorphism, and ontogenesis of ostracods in shell morphology, which are important for correct species identification.

Abstract. Mesoscale eddies are ubiquitous in the Arctic Ocean and are expected to become more numerous and energetic as sea ice continues to decline. Yet, the spatio-temporal characteristics of these eddies are poorly documented. Here, we apply an eddy detection and tracking method to the output of a high-resolution (1/12°) regional model of the Arctic – North Atlantic in order to investigate mesoscale eddies in the Canadian Basin over the period 1995–2020. Over that period, about 6000 eddies per year are detected in the surface layer, while about 9000 eddies per year are detected in the pycnocline layer, and about 5500 eddies per year are detected in the Atlantic Water layer. The eddy population is generally distributed about equally between cyclones and anticyclones. Yet, within the pycnocline and surface layers, a clear dominance of anticyclones over cyclones is found at the centre of the Beaufort Gyre, in line with observations from Ice Tethered Profilers (ITPs). The observed dominance of anticyclonic eddies reported by ITPs thus likely partially arises from the regional focus of the ITPs. On average, eddies travel 11 km, have a radius of 12.1 km, and last 10 d, although the majority of eddies are short-lived (50 % of eddies last less than 4 d). These statistics hide strong regional and temporal disparities within the eddy population. In the surface layer, the seasonal, interannual, and decadal variability in the number of eddies and in their mean characteristics follow that of the sea ice cover. In contrast, within the pycnocline layer and below, the number and properties of eddies show a weakened seasonality. At all depths, the characteristics and density of the eddy population show a strong asymmetry between the slope and the centre of the Canadian Basin. While the upper 85 m show a greater number of eddies over the slope than over the centre of the basin, this pattern is reversed in the pycnocline layer, where a muted eddy activity is observed along the slope and up to 300 km offshore. Within the Atlantic Water layer, a relatively large number of eddies is generated in the vicinity of the cyclonic boundary current along the slope. The vast majority of eddies have a weak temperature and salinity signature with respect to their environment, although a significant portion of the long-lived eddies, located along the Chukchi shelf break, have a relatively large temperature anomaly and penetrate into the Beaufort Gyre, thus suggesting a mechanism for the penetration of heat into the gyre. Over the 26 years analysed here, the number of eddies generated within the upper 85 m increases by 34 %, with the largest increase occurring in the open ocean and marginal ice zone. Within the pycnocline layer, the number of eddies increases by 45 %, with a strong year-long increase in 2008, presumably in response to the Beaufort Gyre spin-up in 2007–2008 associated with the record low in sea ice extent. The number of eddies in the Atlantic Water layer shows an overall increase of 41 %, but little interannual variability. We suggest that this model-based eddy census can thus help investigate recent changes in the dynamical equilibrium of the Beaufort Gyre by providing a consistent spatio-temporal characterization of mesoscale eddies in the Canadian Basin over the past two decades.

Abstract. Warm air intrusions (WAIs) along the North Atlantic pathway are key drivers of warm extremes in the central Arctic. The Svalbard archipelago acts as a major topographic barrier in the middle of this gateway, but its role in modulating WAIs and their impacts has not been studied in detail. We combine (i) high-resolution regional ICON simulations with and without Svalbard’s topography, (ii) Lagrangian back-trajectories, and (iii) observations from the MOSAiC expedition to analyze a strong WAI event in mid-April 2020, and extend the analysis with (iv) climatological composites from an ICON simulation for 2000–2022. Based on the April 2020 case study, we show that Svalbard's influence can extend ∼ 500 km downstream over sea ice and was observed near 84° N during MOSAiC. The response depends on the static stability of the impinging flow: stable conditions favor flow-around response, characterized by accelerated barrier winds along the eastern and western flanks of Svalbard and gap winds through the Hinlopen Strait, together with a broad lee wake north of the archipelago. In this wake, wind speed, near-surface temperature, and column-integrated water vapor are reduced by > 5 m s−1, > 3 K, and > 1 kg m−2, respectively. Under less stable flow-over conditions, föhn signatures yield lower-tropospheric warming (> 1 K) and drying, reduced low-level cloud cover (> 20 %), and decreased (increased) downwelling longwave (shortwave) radiation (> 20 W m−2). Springtime composites reveal that these signals recur during southerly advection events, can extend several hundred kilometers into the central Arctic, and vary in character with poleward wind speed, moisture transport, and static stability linked to the synoptic situation. Together, the results demonstrate that Svalbard's topography systematically modulates the dynamical and thermodynamic imprint of WAIs, with effects detectable far downstream in both model experiments and MOSAiC observations.

ABSTRACT Low trophic marine species are rich in nutrients, making them valuable for food and feed applications. However, these species contain endogenous enzymes that quickly lead to the rapid deterioration of the raw material after harvest. This study investigates how temperature and pH influence proteolytic enzymes in Calanus, krill, Benthosema glaciale, Maurolicus muelleri, and an unsorted biomass sample. Protease activity peak occurred at 50°C for all species, and temperatures above 60°C reduced activity. Across species, Calanus showed the highest proteolytic activity. Future research should focus on enzyme characterization and technological processes to control enzymatic activity while preserving nutrient quality.

Quantifying and attributing model uncertainty in ENSO-induced North Atlantic tropical cyclone genesis using large ensemble simulations

Abstract As a major ocean circulation system, the Atlantic Meridional Overturning Circulation (AMOC) may approach a critical transition under anthropogenic forcing, yet how large-scale AMOC changes imprint on regional circulation pathways remains incompletely understood. While persistent changes in overturning are expected to be meridionally coherent, their horizontal expression may be highly non-uniform. Here, we use 22,000-year-long transient deglacial climate simulations to examine how latitudinally coherent AMOC variations are redistributed across the upper Atlantic circulation. By separating externally forced, long-term AMOC changes from internally generated, short-term variability, we show that the former are disproportionately reflected along the full meridional extent of the South Atlantic western boundary current system. In contrast, North Atlantic counterparts relate primarily to higher-frequency, unforced AMOC variability. Our findings highlight South Atlantic western boundary transports as outstanding fingerprints of past externally forced AMOC changes, thereby outlining their particular sensitivity to a predicted, anthropogenically forced weakening of the AMOC.

Decadal decline of the meridional overturning circulation in the eastern subpolar North Atlantic diagnosed from a high-resolution reanalysis dataset