Sea Surface Temperature Anomalies Research Articles

Interdecadal shifts of ENSO influences on Spring Central Asian precipitation

Spring Central Asian precipitation (SCAP) holds significant implications for local agriculture and ecosystems, with its variability mainly modulated by El Niño–Southern Oscillation (ENSO). The ENSO–SCAP relationship has experienced pronounced interdecadal shifts, though mechanisms remain elusive. Based on observations and climate model simulations, these shifts may result from transitions in ENSO-induced meridional circulation and Rossby wave trains triggered by North Atlantic (NA) sea surface temperature (SST) anomalies. During high (low) correlation periods, ENSO induces strong (weak) vertical motion anomalies over Central Asia, while NA SST anomalies exert a weak (strong) counteracting effect, modulated by the Pacific decadal oscillation (PDO). In the positive (negative) phase of PDO, a slow (fast) decaying ENSO triggers a strong (weak) NA horseshoe-like SST anomaly in the post-ENSO spring, affecting the ENSO–SCAP relationship. Our study identifies a strengthening trend in the ENSO–SCAP relationship since the 2000s, indicating improved predictability for SCAP in recent decades.

The North Pacific Meridional Mode and Its Impact on ENSO in the Second Version of the Chinese Academy of Sciences Earth System Model

AbstractThe North Pacific Meridional Mode (PMM) is the strongest interannual air‐sea coupled system in the subtropical northeastern Pacific, which can significantly impact the development of El Niño and Southern Oscillation (ENSO). This study examines performance of the second version of the Chinese Academy of Sciences Earth System Model (CAS‐ESM2), developed primarily at the Institute of Atmospheric Physics, Chinese Academy of Sciences (IAP/CAS), in simulating the PMM, ENSO, and their relationship. It reveals that CAS‐ESM2 can well reproduce the tropical climate mean states, including sea surface temperature (SST), surface winds, and precipitation. Furthermore, the model shows a good ability in reproducing the seasonal evolutions of the PMM and ENSO. Moreover, CAS‐ESM2 effectively simulates the influence of the PMM on subsequent ENSO and the underlying physical mechanisms, including the wind‐evaporation‐SST feedback process, the trade wind charging mechanism and summer deep convection mechanism. However, some improvements are still needed, particularly in representing the periodicity of the PMM, an overestimation of the ENSO intensity and westward extension of ENSO‐related SST anomalies in the tropical Pacific. The results obtained from the CAS‐ESM2 showcase significant progress in understanding the interaction between air‐sea interaction systems over the tropics and subtropics.

The influence of climate variability events on the mesoscale eddies in the Bay of Bengal

This study investigates the temporal variability of mesoscale eddies in the Bay of Bengal (BoB) over a 29-year period (1993–2021) using satellite altimeters. High-resolution daily sea level anomaly data are considered to identify the mesoscale eddies in the BoB utilizing py-eddy-tracker, an automated eddy detection and tracking method. Wavelet coherence analysis was conducted to find a statistically significant relation between eddy properties and climate indices. The findings indicate that anti-cyclonic eddies are more susceptible to the consequence of the Indian Ocean Dipole (IOD) and El Niño Southern Oscillation (ENSO) than cyclonic eddies. Additionally, the joined impact of ENSO and IOD conceivably alters eddy activities across the BoB, as the second downwelling coastal Kelvin wave (dCKW) were absent. The mesoscale eddies exhibit correlations with climate indicators, suggesting that eddies get stronger during La Niña and negative IOD years and get weaker during El Niño and positive IOD years. This is because La Niña and negative IOD events intensify the second dCKW, while it weakens or becomes completely absent during El Niño and positive IOD years. Random Forest model was used to compare the influence of ENSO and IOD on the forecasting performance of the eddy properties. It was demonstrated that a unique positive IOD (+IOD) negatively affects the forecasting of eddy properties when using Sea Surface Temperature (SST) and SST anomalies. The findings bear importance in verifying and confirming the interactions between the ocean and climate.

El Fenómeno del Niño y la prevalencia de enfermedades infecciosas: revisión

Climate changes caused by the El Niño oscillation southern (ENSO) significantly influence human diseases, because they are related to anomalies in precipitation or periods of drought. The aims of this paper are: to evaluate the anomalies of the average sea surface temperature, to calculate the average sea surface temperature of the Niño and Niño 1+2 regions, to contextualize infectious pathologies according to their classification: viral, bacterial, parasitic and caused by fungi in the geographical areas or countries of the Region where they have been studied in the historical context (1982-1983; 1997-1998 and 2016-2017) periods of the ENSO considered strong. A bibliographic, descriptive, documentary, retrospective and cross-sectional review was carried out during the months of October 2023 to March 2024. Sea Surface Temperatures (SST) are higher than average, observed throughout the equatorial Pacific Ocean, with anomalies being greater in the central and central-eastern Pacific. For ENSO 2023-2024, in the Niño 4 region the last calculated values of the Niño index remained at a temperature of +1.4 °C, in the Niño 3,4 region it was +1.9, in the Niño -3 region it was +2.0 °C while in the Niño-1+2 regions it weakened to +1.0 °C. The highest incidence and prevalence of ENSO infection (1997-1998) in Ecuador stands out, accounting for an increase in 13 infectious pathologies. Attention must be paid and the links between the environment and the risk of infection must be better understood.

Modulation of Pacific decadal oscillation on the relationship between El Niño–Southern Oscillation and rainy season onset over the Indo‐China Peninsula

AbstractMonsoon precipitation variability over the Indo‐China Peninsula (ICP) has become more complicated affected by global warming. In this study, the modulation of Pacific decadal oscillation (PDO) on the relationship between El Niño–Southern Oscillation (ENSO) and the rainy season onset over the ICP were investigated. The results showed that the ICP rainy season onset were predominantly correlated with winter sea surface temperature anomalies (SSTAs) in the East Pacific Ocean, with late and early onsets following El Niño and La Niña events, respectively. During the warm and cold PDO phase, the correlations tended to be substantially strengthened and weakened, respectively. Further analysis indicates that PDO significantly influenced the effects of ENSO on the ICP rainy season onset by modulating SSTAs and low‐level wind fields. During the El Niño events, abnormal easterlies over the Bay of Bengal (BoB) and southern ICP suppressed water vapour transporting to the ICP, which may be related to the zonal SST anomaly gradient between the Indian Ocean and the Northwest Pacific Ocean. When the El Niño occurred during the warm PDO phase, the rainy season onsets were later. The anomalous easterlies became stronger corresponds to the increasing zonal sea surface temperature anomaly (SSTA) gradient between the Indian Ocean and the Northwest Pacific Ocean. There was no significant anomaly on the rainy season onset during the cold PDO phase. During the La Niña events, the abnormal westerlies in BOB accelerated water vapour transport, and the rainy season onset were earlier during the warm and cold PDO phase. The modulating effects of PDO on La Niña were less than those on El Niño. These results suggest that the predictability of rainy season onset over the ICP can be improved through PDO and thus help agricultural planning and water resources management.

Impact of May–June Antarctic Oscillation on July–August Heat-Drought Weather in Yangtze River Basin

Investigating the physical mechanism behind the formation of summer heat-drought weather (HDW) in the Yangtze River Basin (YRB) holds significant importance for predicting summer precipitation and temperature patterns in the region as well as disaster mitigation and prevention. This study focuses on spatiotemporal patterns of July–August (JA) HDW in the YRB from 1979 to 2022, which is linked partially to the preceding May–June (MJ) Antarctic Oscillation (AAO). Key findings are summarized as follows: (1) The MJ AAO displays a marked positive correlation with the JA HDW index (HDWI) in the southern part of upper YRB (UYRB), while showing a negative correlation in the area extending from the Han River to the western lower reaches of the YRB (LYRB); (2) The signal of MJ AAO persists into late JA through a specific pattern of Sea Surface Temperature anomalies in the Southern Ocean (SOSST). This, in turn, modulates the atmospheric circulation over East Asia; (3) The SST anomalies in the South Atlantic initiate Rossby waves that cross the equator, splitting into two branches. One branch propagates from the Somali-Tropical Indian Ocean, maintaining a negative-phased East Asia–Pacific (EAP) teleconnection pattern. This enhances the moisture flow from the Pacific towards the middle and lower reaches of the Yangtze River Basin (MYRB-LYRB). The other branch propagates northward, crossing the Somali region, and induces a positive geopotential height anomaly over Urals-West Asia. This reduces the southwesterlies towards the UYRB, thereby contributing to HDW variabilities in the region. (4) Partial Least Squares Regression (PLSR) demonstrated predictive capability for JA HDW in the YRB for 2022, based on Southern Ocean SST.

Mapping phenoregions and phytoplankton seasonality in Northeast Pacific marine coastal ecosystems via a satellite-based approach

Phytoplankton phenology describes yearly algal growth cycles and characterises the timing, duration, and magnitude of bloom occurrences. This study used satellite chlorophyll-a data from 1998 to 2020 and the Hierarchical Agglomerative Clustering method to define phenoregions based on phytoplankton phenology spatial patterns over the British Columbia and Southeast Alaska coastal oceans. The defined phenoregions were used to simplify the spatial complexity of the heterogenous study region and thus better describe phytoplankton seasonality across the target area. The cluster analysis allowed the delineation of four coherent regions: two coastal regions and northern and southern shelf/offshore regions. Results showed that each phenoregion had distinguishable phytoplankton phenological characteristics, likely due to different physical forcings acting in these areas. Moreover, the interannual variability of the spring bloom initiation was evaluated considering interactions between sea surface temperature (SST) anomalies and the El Niño Southern Oscillation Index (ENSO). Early spring blooms were associated with positive SST anomalies and El Niño conditions; conversely, average or late spring blooms occurred in years with negative SST anomalies and La Niña conditions, with the strongest relationship occurring in the southern shelf/offshore phenoregion. This study provided new insights into the regionalisation of the British Columbia and Southeast Alaska coastal oceans based on phytoplankton phenology patterns. Given the critical role of phytoplankton as the base of the marine food web, such phenoregions have implications for regional zooplankton biomass and fish production. The link between phytoplankton phenology and climate drivers points to the importance of environmental change in phytoplankton bloom dynamics. Further research into the connection between phytoplankton bloom indices and zooplankton community structure and production would be an important step towards using these indices for ecosystem monitoring and fisheries management.

Late Ming Dynasty weak monsoon induced a harmonized megadrought across north-to-south China

Historians and paleoclimatologists have long studied the connection between ecoclimatic changes and empire growth, transformation, and decline, but striking cases remain rare. Here, we introduce a tree-ring chronology from southern China to reconstruct changes in April-to-November water balance of the middle reaches of the Yangtze River over the last 464 years. The reconstruction supports a quantitative assessment of the spatiotemporal structure of the late Ming megadrought and potential effects on subsequent dynastic transitions. Our results indicate that the late Ming megadrought from 1625 – 1644 CE occurred in both the northern and southern parts of the East Asian monsoon region in China. However, variations in the onset, duration, and magnitude of this event differ between regions. The combination of factors such as Pacific sea surface temperature anomalies, weakened solar activity, and large-scale volcanic eruptions may have contributed to the occurrence of the late Ming megadrought. These factors are also identified as key drivers of interannual to decadal fluctuations in drought in the middle reaches of the Yangtze River. Our reconstruction provides an historical context for the development of adaptive measures to mitigate future drought impacts in the region.

Evaluation of tropical cyclone genesis frequency in FGOALS-g3 large ensemble: mean state and interannual variability

The tropical cyclone genesis frequency (TCGF) is an essential metric for gauging the performance of climate models. Previous evaluations on CMIP family models usually employ one realization for each model and show their diversities in performance. The single model initial condition large ensemble experiments provide a unique opportunity to quantify how internal variability may affect the model evaluation skill. Here, taking the TCGF in the Western North Pacific (WNP) as an example, we use two genesis potential indices as proxies to evaluate the performance of the FGOALS-g3 large ensemble simulation with 110 members. We show that while internal variability does not have a significant influence on the TCGF mean state evaluation, the TCGF-ENSO (El Niño–Southern Oscillation) relationship is significantly modulated by the decadal scale internal variability. For mean state simulation, the FGOALS-g3 large ensembles show reasonable performance in the simulation of TCGF spatial pattern but have differences compared with ERA5 in magnitude. Physical process analysis indicates that compared with ERA5, nearly all dynamic terms are more unfavorable for tropical cyclogenesis due to the cold sea surface temperature anomalies in the midlatitude, while the thermodynamic terms are more conducive to more TCs. For interannual variability, the ENSO-TCGF connection is significantly modulated by the tropical Pacific decadal variability (TPDV) mode by influencing the vertical wind shear in the WNP. Particularly, the model simulation skill depends on the choice of genesis potential indices. Our finding highlights the importance of considering decadal-scale internal variability in the evaluation of interannual ENSO-TCGF variability.

Diverse Responses of Strong Positive SST and Rainfall Indian Ocean Dipole Events under Greenhouse Warming

Abstract Recent research has shown that there is a projected increase in the frequency of strong positive Indian Ocean dipole (spIOD) events in terms of both sea surface temperature (SST) and precipitation. However, it is not clear whether the spIOD events defined by SST and precipitation, hereafter referred to as SST-spIOD and Pr-spIOD events, respectively, will increase at the same pace under greenhouse warming. Using climate models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) and CMIP6 that can reasonably simulate the spIOD events, here we find that the occurrence of Pr-spIOD events increases much more than that of SST-spIOD events (+217% vs +77%) under the future high-emission scenario. The diverse response stems from a notably large increase in the spIOD events with strong rainfall but moderate SST anomalies (Pr-only spIOD), which is facilitated by a change in the local meridional Hadley circulation induced by land–sea thermal contrast in addition to the background mean-state SST warming. For the spIOD events with prominent anomalies in both rainfall and SST (concurrent spIOD), their occurrences are projected to increase, but their average SST amplitude is projected to weaken. The increased occurrence is associated with a westward-extended structural change induced by mean linear zonal advection feedbacks, while the weakened event-average SST amplitude results from a more stabilized atmosphere and coincides with the projected reduction in IOD SST skewness. Our results suggest that IOD-related mitigation strategies should consider the diverse responses of different kinds of spIOD events to greenhouse warming.

50-year seasonal variability in East African droughts and floods recorded in central Afar lake sediments (Ethiopia) and their connections with the El Niño–Southern Oscillation

Abstract. Understanding past and present hydrosystem feedbacks to global ocean–atmospheric interactions represents one of the main challenges to preventing droughts, extreme events, and related human catastrophes in the face of global warming, especially in arid and semiarid environments. In eastern Africa, the El Niño–Southern Oscillation (ENSO) was identified as one of the primary drivers of precipitation variability affecting water availability. However, the northern East African Rift System (EARS) still suffers from the underrepresentation of predictive and ENSO teleconnection models because of the scarcity of local to regional historical or palaeo-data. In this paper, we provide a 50-year seasonal flood and drought chronicle of the Awash River catchment from the study of laminated sediment from Gemeri and Afambo lakes (central Afar region, Ethiopia) with the aim of reconstructing the magnitude of regional hydroclimatic events. Pluricentimetric micro-laminated lithogenic facies alternating with plurimillimetric carbonate-enriched facies are investigated in both lakes. We couple dating methods including radiocarbon, short-lived radionuclides, palaeomagnetic field variations, and varve counting on both lake deposits to build a high-resolution age model and to discuss the regional hydrosedimentary dynamics of the Awash River over the last ∼ 700 years with a focus on the last 50 years. Using a multiproxy approach, we observe that following a multicentennial enhanced hydrological period, the two lakes have experienced a gradual decrease in river load inflow since 1979 CE, attaining extreme drought and high evaporative conditions between 1991 and 1997 CE. In 2014, the construction of a dam and increased agricultural water management in the lower Awash River plain impacted the erodibility of local soils and the hydrosedimentary balance of the lake basins, as evidenced by a disproportionate sediment accumulation rate. Comparison of our quantitative reconstruction with (i) lake water surface evolution, (ii) the interannual Awash River flow rates, and (iii) the El Niño 3.4 model highlights the intermittent connections between ENSO sea surface temperature anomalies, regional droughts, and hydrological conditions in the northern EARS.

Warming of mid-latitude North Atlantic Sea surface temperature strengthens the daily variability of winter PM2.5 in eastern China

Abstract Climate factors, in addition to human activities, are acknowledged to exert a notable influence on the synoptic PM2.5 variations over eastern China in extensive case studies. Based on observed daily PM2.5 concentrations data, this study reveals the enhanced daily variability (DV) of PM2.5 concentrations over eastern China and identifies its association with mid-latitude sea surface temperature anomalies over the North Atlantic. The dominant daily mode of PM2.5 concentrations identified through empirical orthogonal function analysis accounts for 43.75% of the total variance, with its DV experienced a significant enhancement from 1979 to 2019. The identified enhancement is attributed to the intensified wave train propagation along the mid-latitudes on a time scale of 10–30 d. The eastward propagation of the identified wave train can expose eastern China to recurrent influences of cyclonic and anticyclonic anomalies, resulting in an initial increase and subsequent decrease in PM2.5 concentrations. Statistical analysis and dynamic diagnostics show that the warming of the mid-latitude North Atlantic Ocean enhances the wave train at its source through the local energy exchange, and ultimately leads to an increased DV of PM2.5 concentrations.

Interannual relationship of the extreme precipitation dipole mode over South China and Indochina Peninsula with the tropical Pacific-Indian Ocean sea surface temperature anomaly in May

This study investigates the interannual relationship of extreme precipitation days (EPD) over South China (SC) and Indochina Peninsula (ICP) with tropical Pacific-Indian Ocean Sea surface temperature (SST) anomalies during May, utilizing observations, reanalysis, and Coupled-Model Intercomparison Project 6 (CMIP6) model outputs. The results uncover a dipole mode in the interannual variations of May EPD over SC and ICP, characterized by an east–west inverse pattern. This dipole mode is significantly attributed to large-scale circulation anomalies induced by tropical Pacific–Indian Ocean mode (PIM). During the positive phase of PIM, SST anomalies in the tropical east-central Pacific and western Indian Oceans are anomalously warm, contrasted with negative SST anomalies in the western Pacific, leading to anomalous Walker circulations. Accordingly, two robust anticyclones appear in the lower levels of the Northwest Pacific and the Bay of Bengal, respectively. The southwesterlies on the western flank of the anticyclone in the Northwest Pacific cause moisture convergence over SC, favoring the occurrence of extreme precipitation in SC. Conversely, the anticyclonic circulation centered at the Bay of Bengal is not conducive to the transport of warm water vapor from oceans to ICP, resulting in reduced occurrence of extreme precipitation there. The results derived from CMIP6 models unequivocally support the notion that the dipole mode is predominantly shaped by large-scale circulation anomalies induced by PIM. Our results underscore the importance of accounting for the collective impact of oceanic drivers in the tropics, laying a scientific foundation for enhanced precision in simulating extreme precipitation across SC and ICP.

Contribution of internal variability to the Mongolian Plateau summer precipitation trends in MPI-ESM large-ensemble model

Summer precipitation over the Mongolian Plateau (MP) has experienced a consistent decline in recent decades. While the influence of atmospheric wave train on this reduction in precipitation has been recognized in prior studies, this study delves deeper into the physical mechanisms and quantifies the contributions of the internal atmosphere and oceanic variations to the diminishing precipitation utilizing a comprehensive 100-member ensemble simulations from the Max Planck Institute Earth System Model (MPI-ESM). Results show that the ensemble-mean precipitation in MP exhibits a positive trend and cannot explain the observed results. The precipitation trends vary significantly among individual ensemble members, highlighting the pivotal role of internal variability. The leading EOF mode of precipitation trends among ensemble members exhibits uniform variations. Further investigations reveal that the internal summer precipitation in MP is affected by the internal atmospheric circulation, the remote influence of the North Atlantic Dipole sea surface temperature (SST) anomalies, and Pacific Decadal Oscillation-like SST patterns. An eastward-propagating Rossby wave originating from the North Atlantic dipole SST anomalies provides the anomalous large-scale circulation that influences summer precipitation. The PDO contributes to reinforcing the anticyclonic anomaly over the MP. Additionally, the uncertainty of precipitation trends in MPI-ESM can be reduced by 13% through removing the internal atmospheric wave train-related precipitation variation, while oceanic factors only contribute about 7% uncertainty of precipitation variations. Our insights enhance the understanding of the physical drivers behind summer precipitation variability in the MP and effectively quantify the uncertainties stemming from internal variability.

Climatic influence of the Antarctic ozone hole on the East Asian winter precipitation

The Antarctic ozone hole exerts a substantial impact on the climate of the Southern Hemisphere, yet research exploring its potential influence on the Northern Hemisphere climate is limited. This study unveils a significant positive relationship between interannual variations of Antarctic total column ozone (TCO) during September–October and East Asian precipitation in the subsequent boreal winter. Specifically, ~10% of the East Asian winter precipitation variability is attributed to Antarctic TCO during September–October. Both observational data and model results indicate that the increased Antarctic TCO during September–October triggers a simultaneous meridional southern Indian Ocean tripole sea surface temperature anomalies (SSTA) through the negative phase of the Southern Annular Mode. This SSTA pattern persists from September–November through the boreal winter, subsequently weakening the local-scale zonal-vertical circulation anomalies in the Indian Ocean. The process leads to positive outgoing longwave radiation (OLR) anomalies over the southern Marine Continent. As a result, the linear response of wind anomalies at 850 hPa over East Asia to the OLR-induced diabatic heating anomalies exhibits southwesterlies, as demonstrated by a linear baroclinic model. These anomalous winds facilitate the transport of abundant moisture from the tropics to East Asia, favoring the formation of winter precipitation. We employ the Specified-Chemistry version of the Whole Atmosphere Community Climate Model to validate that the increase of September–October Antarctic ozone substantially enhances East Asian precipitation during boreal winter. Importantly, the relationship between Antarctic ozone and East Asian winter precipitation is found to be independent of El Niño-Southern Oscillation and the Indian Ocean Dipole Mode. Our findings provide a fresh insight into the prediction of the East Asian winter precipitation.

The interplay between medicanes and the Mediterranean Sea in the presence of sea surface temperature anomalies

This study examined three Mediterranean Sea cyclones classified as medicanes: Zorbas, Ianos, and Apollo. All three cyclones traversed warm-core eddies during their propagation. We investigated the role of those eddies in the cyclones' development and the responses of those eddies to the passage of a cyclone. Cyclones Zorbas and Apollo intensified considerably in close proximity to warm-core eddies; whereas Ianos, the strongest cyclone ever recorded in the Mediterranean Sea (reaching Category 2), underwent marginal intensification. In the case of Ianos, a strong marine heatwave was present during the intensification, releasing more latent and sensible heat fluxes due to the high ocean heat content, which masked the effect of the warm core eddy. For Zorbas and Apollo, the intensification above the warm-core eddy was accompanied by moisture convergence at the warm-core eddy, yielding substantial precipitation. In the case of Ianos, the convergence of moisture and subsequent precipitation aligned with the occurrence of a marine heatwave. For Zorbas and Apollo, chlorophyll-a concentrations and Phytoplankton increased after the cyclone passed over a warm-core eddy; whereas for Ianos, they increased near the site of a marine heatwave. All three cyclones responded similarly to elevated temperatures at the mesoscale (i.e., warm-core eddy) and regional scale (i.e., marine heatwave).

Pivotal Role of Mixed‐Layer Depth in Tropical Atlantic Multidecadal Variability

AbstractThe tropical arm of Atlantic Multidecadal Variability (AMV) influences climate worldwide, yet the mechanisms generating it remain unclear. Here, we examine experiments with sea surface temperature (SST)‐restoring in the extratropical North Atlantic in multiple models and use mixed‐layer heat budgets to elucidate the important mechanisms. Our results demonstrate that the tropical AMV is driven by wind‐mixed‐layer‐SST feedback. The evolution has two phases with tropical AMV SST anomalies growing from April to October and decaying from November to March. The amplitude of the growth phase surpasses that of the decay phase, resulting in overall tropical Atlantic warming during positive AMV phases. During summer, positive SST anomalies in the extratropics weaken the trade winds, resulting in a shallower mixed‐layer with reduced heat capacity. Subsequent absorption of climatological shortwave radiation in this shallower mixed‐layer then causes SSTs to warm, generating the tropical AMV. Importantly, anomalous surface heat‐fluxes make modest contributions to tropical AMV in these experiments.

The out‐of‐phase pattern of summer precipitation over northern China and the possible mechanisms

AbstractThis study explored the interannual characteristics of the out‐of‐phase pattern of summer precipitation over northern China during the past years, as well as the possible underlying mechanisms. The out‐of‐phase pattern is characterized by the positive precipitation anomaly in Northwest China (NWC) and the negative anomaly in North China (NC). Our analyses indicate that the variation of Asian westerly jet (AWJ) is found evidently associated with this out‐of‐phase pattern of summer precipitation. The meridional displacement of AWJ induces opposite trends in water vapour transport and circulation anomalies between NWC and NC, leading to the out‐of‐phase pattern. Further analyses suggest that the anomalies of Arctic sea ice concentration (SIC), North Atlantic and Northwest Pacific sea surface temperature (SST) can impact the variation of AWJ by triggering the Eurasian (EU), polar‐Eurasia (POL) and Pacific‐Japan (PJ) teleconnection patterns, respectively, which in turn modulate the formation of this pattern. The precipitation in NWC is primarily affected by the North Atlantic and Northwest Pacific SST anomalies, whereas the precipitation in NC is notably influenced by both SST anomalies and the Arctic SIC anomaly. However, the role of SST anomalies on precipitation in NWC and NC exhibits an evident contrast, leading to the out‐of‐phase pattern of summer precipitation.

Highest ocean heat in four centuries places Great Barrier Reef in danger

Mass coral bleaching on the Great Barrier Reef (GBR) in Australia between 2016 and 2024 was driven by high sea surface temperatures (SST)1. The likelihood of temperature-induced bleaching is a key determinant for the future threat status of the GBR2, but the long-term context of recent temperatures in the region is unclear. Here we show that the January–March Coral Sea heat extremes in 2024, 2017 and 2020 (in order of descending mean SST anomalies) were the warmest in 400 years, exceeding the 95th-percentile uncertainty limit of our reconstructed pre-1900 maximum. The 2016, 2004 and 2022 events were the next warmest, exceeding the 90th-percentile limit. Climate model analysis confirms that human influence on the climate system is responsible for the rapid warming in recent decades. This attribution, together with the recent ocean temperature extremes, post-1900 warming trend and observed mass coral bleaching, shows that the existential threat to the GBR ecosystem from anthropogenic climate change is now realized. Without urgent intervention, the iconic GBR is at risk of experiencing temperatures conducive to near-annual coral bleaching3, with negative consequences for biodiversity and ecosystems services. A continuation on the current trajectory would further threaten the ecological function4 and outstanding universal value5 of one of Earth’s greatest natural wonders.

Unraveling climate trends in the mediterranean: a hybrid machine learning and statistical approach

This study presents a comprehensive spatiotemporal analysis of sea surface temperatures (SST) and surface air temperatures (TAS) across 15 Mediterranean coastal stations, leveraging centennial-scale data to analyze regional climate dynamics. The modeling framework integrates three sequential phases: data preprocessing, statistical analysis, and advanced machine learning techniques, creating a robust analytical pipeline. The data preprocessing phase harmonizes diverse datasets, addresses missing values, and applies transformations to ensure analytical consistency. The statistical modeling employs the Pettitt test for change point detection and linear trend analysis to unveil underlying patterns. The machine learning phase utilizes K-means clustering for climate regime classification and implements tailored Convolutional Neural Networks (CNNs) for cluster-specific future climate anomaly projections. Results unveil a marked anthropogenic climate signal, with contemporary observations consistently surpassing historical baselines. Breakpoint analyses and linear trend assessments reveal heterogeneous climatic shifts, with pronounced warming in the northern Mediterranean. Notably, Nice and Ajaccio exhibit the highest SST increases (0.0119 and 0.0113 °C/decade, respectively), contrasting with more modest trends in Alexandria (0.0052 °C/decade) and Antalya (0.0047 °C/decade) in the eastern Mediterranean. The application of clustering and CNN projections provides granular insights into differential warming trajectories. By 2050, cooler northwestern Mediterranean zones are projected to experience dramatic SST anomalies of approximately 3 °C above the average, with corresponding TAS increases of 2.5 °C. In contrast, warmer eastern and southern regions display more subdued warming patterns, with projected SST and TAS increases of 1.5–2.5 °C by mid-century. This research’s importance is highlighted by its potential to inform tailored adaptation strategies and contribute to the theoretical understanding of climate dynamics, advancing climate modeling and analysis efforts.