Extreme El Research Articles

Tropical lacustrine sediment microbial community response to an extreme El Niño event

Salinity can influence microbial communities and related functional groups in lacustrine sediments, but few studies have examined temporal variability in salinity and associated changes in lacustrine microbial communities and functional groups. To better understand how microbial communities and functional groups respond to salinity, we examined geochemistry and functional gene amplicon sequence data collected from 13 lakes located in Kiritimati, Republic of Kiribati (2° N, 157° W) in July 2014 and June 2019, dates which bracket the very large El Niño event of 2015–2016 and a period of extremely high precipitation rates. Lake water salinity values in 2019 were significantly reduced and covaried with ecological distances between microbial samples. Specifically, phylum- and family-level results indicate that more halophilic microorganisms occurred in 2014 samples, whereas more mesohaline, marine, or halotolerant microorganisms were detected in 2019 samples. Functional Annotation of Prokaryotic Taxa (FAPROTAX) and functional gene results (nifH, nrfA, aprA) suggest that salinity influences the relative abundance of key functional groups (chemoheterotrophs, phototrophs, nitrogen fixers, denitrifiers, sulfate reducers), as well as the microbial diversity within functional groups. Accordingly, we conclude that microbial community and functional gene groups in the lacustrine sediments of Kiritimati show dynamic changes and adaptations to the fluctuations in salinity driven by the El Niño-Southern Oscillation.

Effect of extreme El Niño events on the precipitation of Ecuador

Abstract. Extreme El Niño events stand out not only because they have powerful impacts but also because they are significantly different from other El Niños. In Ecuador, such events are accountable for negatively impacting the economy, infrastructure, and population. Spatial–temporal dynamics of precipitation anomalies from various types of extreme El Niño events are analyzed and compared. Results show that for eastern Pacific (EP) and coastal Pacific (COA) El Niño types, most precipitation extremes occur in the first half of the second year of the event. Any significant difference between events becomes more evident at this stage. Spatially, for any event, 50 % of all extreme anomalies occurred at elevations < 150 m. The difference between events was significant when considering the altitude when reaching 80 % of all extreme anomalies: the eastern Pacific (EP) El Niño from 1997/98 (EP98) at 500 m, the El Niño from January to April 2017 (COA17) at 800 m, and the EP El Niño from 1982/83 (EP83) at 1000 m. Nevertheless, in some sectors of the Andean Cordillera, the El Niño–Southern Oscillation (ENSO) signal could be detected at 3200–3900 m. The distance to the coastline and the steepness of relief may play a determining role. At lowlands, anomalies are most severe in regions where the seasonality index is the highest. These results are useful at different decision-making levels for identifying the most appropriate practices reducing vulnerability from a potential increase in extreme El Niño frequency and intensity.

The south–north equatorial asymmetrical distribution of Chlorophyll in El Niño events in the observations and CMIP6 models

The interannual variability of chlorophyll (Chl) in the tropical Pacific Ocean is influenced by El Niño. When El Niño occurs, insufficient nutrients (suppressed upwelling), reduced shortwave radiation reaching the surface (increased precipitation), and eastward zonal current (U) anomalies, which transport low Chl from western Pacific warm pool water to the east, can cause a reduction in tropical Pacific Chl. The El Niño-induced Chl anomaly is asymmetrically distributed across the equator between 10°S and 10°N, and is particularly significant in extreme El Niño events. This asymmetric phenomenon is mainly caused by asymmetrical anomalies of the eastward U and precipitation. During El Niño events, U and precipitation anomalies are much stronger north of the equator, which can cause a greater reduction in Chl, which is asymmetrical. Models from the Coupled Model Intercomparison Project Phase 6 (CMIP6) are used to evaluate the simulation of the south–north asymmetry of Chl under extreme El Niño events. It finds that the simulation of U and precipitation anomalies is the key parameter to the simulation of this asymmetry. Among 15 CMIP6 models that provided Chl data, only 5 of them (MIROC-ES2 L, MPI-ESM1-2-HR, MPI-ESM1-2-LR, NorESM2-LM, and NorESM2-MM) can be used to investigate the asymmetrical distribution of Chl during extreme El Niño after comparison with observational Chl. Among the 5 selected models, only 2 (NorESM2-LM, NorESM2-MM) can show asymmetry during extreme El Niño events, and the other three models (MIROC-ES2 L, MPI-ESM1- (MIROC-ES2 L, MPI-ESM1-2-HR, MPI-ESM1-2-LR, NorESM2-LM, and NorESM2-MM) 2-HR, MPI-ESM1-2-LR) show symmetrical distributions. From the composite distribution of U and precipitation for these five models, it can be seen that the key reasons for whether a model can simulate the asymmetry lies in the simulation of U and precipitation.

A Novel Mechanism for Extreme El Niño Events: Interactions between Tropical Cyclones in the Western North Pacific and Sea Surface Warming in the Eastern Tropical Pacific

Abstract This study presents a novel mechanism for the generation of extreme El Niño events by analyzing interactions between tropical cyclones (TCs) in the western North Pacific (WNP) in spring [March–May (MAM)] and summer [June–August (JJA)] and sea surface warming in the eastern tropical Pacific. It is suggested that anomalously strong TCs in the WNP in MAM and JJA are essential for the formation of extreme El Niño events. MAM TCs excite considerable westerly wind bursts (WWBs) and facilitate the generation of El Niño events in late spring. The sea surface temperature (SST) in the central-eastern tropical Pacific increases prominently during the following summer, which is due to the warm water carried by downwelling Kelvin waves induced by the anomalous westerlies in the western tropical Pacific associated with the WNP TCs, as well as the lessening cold water upwelling resulting from the deepening thermocline in the eastern tropical Pacific. The developing El Niño in turn contributes to the TC activities over the southeastern quadrant of the WNP in summer, characterized by a stronger intensity, higher frequency, and longer duration. The resulting JJA TC-induced westerlies could further enhance the eastern tropical Pacific warm SST anomalies, and thus an extreme El Niño event tends to appear in the following autumn and winter. These physical processes are verified by several sets of atmosphere–ocean coupled model experiments. Significance Statement Tropical cyclone activity is one of the most destructive phenomena in the world. Extreme El Niño events can also cause devastating climate disasters. Understanding the relationship between these two events can help with disaster forecasting and prevention. This study finds that TC activity in the western North Pacific contributes to the appearance of extreme El Niño events. Abnormally active TC activity in spring can cause strong near-equatorial westerly wind anomalies, eastward transport of warm water from the western tropical Pacific, and a deepening ocean thermocline in the east, resulting in the earlier onset of El Niño events. Influenced by the El Niño event, the TC activity in summer is strengthened, which in turn continues to promote the surface warming of the central-eastern tropical Pacific, eventually resulting in extreme event occurrence.

Changes and Mechanisms of Long-Lived Warm Blobs in the Northeast Pacific in Low-Warming Climates

Abstract In the last decade, three persistent warm blob events (2013/14, 2015, and 2019/20) in the northeast Pacific (NEP) have been hotly debated given their substantial effects on climate, ecosystems, and the socioeconomy. This study investigates the changes of such long-lived NEP warm blobs in terms of their intensity, duration, structure, and occurrence frequency under Shared Socioeconomic Pathway (SSP) 119 and 126 low-warming scenarios of phase 6 of the Coupled Model Intercomparison Project. Results show that the peak timing of the warm blobs shifts from the cold season to boreal summer. For the summer-peak warm blobs, their maximum intensity increases by 6.7% (10.0%) under the SSP119 (SSP126) scenario, but their duration reduces by 31.0% (20.4%) under the SSP119 (SSP126) scenario. In terms of their vertical structure, the most pronounced temperature signal is located at the surface, and their vertical penetration is mostly confined to the mixed layer, which becomes shallower in warming climates. Based on a mixed layer heat budget analysis, we reveal that a shoaling mixed layer depth plays a dominant role in driving the stronger intensity of the warm blobs under low-warming scenarios, while the stronger magnitude of ocean heat loss after their peaks explains the faster decay and thus shorter duration. Regarding occurrence frequency, the total number of the warm blobs does not change robustly in the low-warming climates. Following the summer peak of the warm blobs, extreme El Niño events may occur more frequently under the low-warming scenarios, possibly through stronger air–sea coupling induced by tropical Pacific southwesterly anomalies.

Extreme El Niño southern oscillation conditions have contrasting effects on the body condition of five euphausiid species around the northern Antarctic Peninsula during winter

El Niño southern oscillation (ENSO) events drive profound global impacts on marine environments. These events may result in contrasting conditions in the Southern Ocean, with differing effects on euphausiid species because of their diverse life histories, habitats, and feeding ecologies. We conducted oceanographic surveys during winter (2012–2016) around the northern Antarctic Peninsula and examined the dietary carbon sources, trophic position, and body condition of five euphausiid species (Euphausia crystallorophias, E. frigida, E. superba post-larvae and larvae, E. triacantha, and Thysanoessa macrura) in relation to environmental conditions each year. In addition to general patterns among taxa, we focused on how contrasting conditions during an ENSO-neutral year (2014) and an ENSO-positive year (2016) affected the type, quality, and distribution of food resources each year, as well as the body condition of each species. We observed high chlorophyll-a, low salinity, and shallow upper mixed-layer depths in 2014, and low chlorophyll-a, high salinity, and deep upper mixed-layer depths in 2016. Carbon sources varied among years, with most species enriched in δ13C when ENSO conditions were dominant. Trophic position and body condition also varied among years, with different responses among species depending on conditions; inter-annual variation in δ15N was minimal, while E. triacantha was the only species with notably lower body condition in 2016. We conclude that ENSO conditions around the northern Antarctic Peninsula may result in a more favorable feeding environment for all euphausiid species except E. triacantha, which may be the most negatively impacted by the predicted increase in ENSO conditions.

Role of Tropical Cyclones in Determining ENSO Characteristics

AbstractEl Niño‐Southern Oscillation (ENSO) can effectively modulate global tropical cyclone (TC) activity, but the role TCs may play in determining ENSO characteristics remains unclear. Here we investigate the impact of TC winds on ENSO using a suite of Earth system model experiments where we insert TC winds, extracted from a TC‐permitting high‐resolution simulation, into a low‐resolution model configuration with nearly no intrinsic TCs. The presence of TC winds in the model increases ENSO power and shifts ENSO frequency closer to what we observe. TCs lead to an increase of strong to extreme El Niño events seen in observations and not simulated in the low‐resolution model without intrinsic TCs, mainly through enhanced zonal advection feedback and thermocline feedback. Our results indicate that TCs play a fundamental role in producing the ENSO characteristics we experience today in the climate system and point to a two‐way climatological interaction between TCs and ENSO.

Settlement dynamics, subsistence economies and climate change during the late Holocene at Nunura Bay (Sechura Desert, Peru): A multiproxy approach.

Long considered on the margins, far from the major cultural traditions, the Sechura Desert is situated at the crossroads between the cultures of southern Ecuador and those of the northern Peruvian coast and preserves a large number of varied archaeological sites. Despite this evidence, little is known about the societies that inhabited this region during the Holocene. Exposed to natural hazards, including El Niño events, and to major climatic changes, they were able to adapt and exploit the scarce resources that this extreme environment offered them. Because of this rich history, we have been conducting archaeological research in this region since 2012 in order to clarify the dynamics of human occupation and their links with climate oscillations and environmental changes. This paper present the results of a multidisciplinary study of Huaca Grande, a mound located on Nunura Bay, 300 m from the Pacific Ocean. The nature of the human occupations at Huaca Grande was varied, and several adjustments occurred over time. The subsistence economy was based mainly on local marine resources and a continual use of terrestrial vegetal resources. However, a major change occurred in the more recent occupations, with the apparition of non-local resources (maize and cotton) indicating that Huaca Grande was connected to trade networks. The results show two main phases of occupation separated by a long abandonment (mid-5th century CE to mid-7th century CE and mid-13th century to mid-15th century CE). The occupation of the site appears to have been influenced by changes in the local climate and by extreme El Niño events. Our results highlight the great adaptability of these human groups over the span of a millennium and their capacity to react to the climatic changes and hazards that characterise this region.

ENSO teleconnections in terms of non-NAO and NAO atmospheric variability

The validity of the long-held understanding or assumption that El Niño-Southern Oscillation (ENSO) has a remote influence on the North Atlantic Oscillation (NAO) in the January–February–March (JFM) months has been questioned recently. We examine this claim further using atmospheric data filtered to separate the variability orthogonal and parallel to NAO. This decomposition of the atmospheric fields is based on the Principal Component/Empirical Orthogonal Function method whereby the leading mode of the sea-level pressure in the North Atlantic sector is recognised as the NAO, while the remaining variability is orthogonal (unrelated) to NAO. Composite analyses indicate that ENSO has statistically significant links with both the non-NAO and NAO variability at various atmospheric levels. Additional bootstrap tests carried out to quantify the uncertainty and statistical significance confirm these relationships. Consistent with previous studies, we find that an ENSO teleconnection in the NAO-related variability is characterised by lower-stratospheric eddy heat flux anomalies (related to the vertical propagation of planetary waves) which appear in November–December and strengthen through JFM. Under El Niño (La Niña), there is constructive (destructive) interference of anomalous eddy heat flux with the climatological pattern, enhancing (reducing) fluxes over the northern Pacific and Barents Sea areas. We further show that the teleconnection of extreme El Niño is essentially a non-NAO phenomenon. Some non-linearity of the teleconnections is suggested, with El Niño including more NAO-related variability than La Niña, but the statistical significance is degraded due to weaker signals and smaller sample sizes after the partitioning. Our findings have implications for the general understanding of the nature of ENSO teleconnections over the North Atlantic, as well as for refining methods to characterise and evaluate them in models.

Seasonal variability of satellite-derived primary production in the South China Sea from an absorption-based model

Seasonal patterns of marine net primary production (NPP) are crucial for understanding the marine ecosystem and biogeochemical cycles. Uncoupling of seasonal variations between NPP and phytoplankton chlorophyll-a over different areas has attracted much attention. In this study, following a review of previous studies, monthly climatological NPP data from 2003 to 2020, estimated using the Size-fractioned Phytoplankton Pigment Absorption (aph)-based NPP Model (SABPM), were selected to study the seasonal variability of NPP in the South China Sea (SCS). Results showed the spatial differences of NPP seasonality and its departures from climatology in extreme El Niño-Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) years. Cluster analysis for climatological monthly data identified significant differences of NPP seasonality in five typical regions. In coastal regions along the northern SCS and off eastern Vietnam, NPP exhibited the most obvious seasonal cycle with maximum (minimum) values in summer (winter), attributable mainly to river discharge and summer upwelling. In regions off northwestern Luzon and coast of southern SCS, NPP showed peaks in winter, which were related to strong mixing and upwelling. In northwestern SCS, NPP was high during May–September in phase with sea surface temperature and the primary controlling factors were found to be shallow nutricline depth and wind-driven mixing. Owing to the deep nutricline depth in the central basin, NPP exhibited little seasonal variability; only a weak signal was observed in spring in phase with photosynthetically active radiation. Local dynamics on regulating the nutrient supply and light availability contribute to these regional differences in NPP seasonality, which could also be affected by extreme climate events. The largest anomalies of the NPP seasonal cycle coincide with 2015/2016 ENSO and super IOD in 2020. During these events, enhanced (weakened) westerly winds caused fall (rise) of SLA and increase (decrease) of NPP in coastal regions along the northern SCS and that off eastern Vietnam. Overall, theaph-based model shows a new perspective to study the spatiotemporal variations of NPP in the SCS.

Anomali Iklim El Nino dan La Nina di Indonesia pada 2013-2022

Climate anomaly phenomena are increasing in frequency and duration along with the occurance of global warming phenomena. El Nino and La Nina climate anomalies have a direct impact on agriculture. This study aims to analyze the occurrence of extreme climate phenomena El Nino and La Nina in 2012-2022 in Indonesia and their impact on rainfall in South Sumatera Province which is one of the centers of oil palm plantations. The research was conducted by identifying sea surface temperature (SST) anomalies in the Pacific Ocean and classifying them into El Nino and La Nina strength levels or normal conditions. Based on the sea surface temperature anomaly, it is known that Indonesia experienced strong El Nino events in 2014-2015 and weak El Nino in 2019. El Nino causes a prolonged dry season and decreases the amount of rainfall. The La Nina phenomenon occurs in 2020-2022 with weak to moderate strength. La Nina causes a prolonged rainy season and an increase in the amount of rainfall. Normal conditions occurred in 2013, 2016, 2017 and 2018 which were marked by sst anomalies of not more than +0.5°C and -0.5 °C. During normal conditions, South Sumatra Province has an annual rainfall of 2,500 mm, rainfall is evenly distributed throughout the year, and dry months are less than 3 months that suitable for oil palm cultivation. In the last 10 years, Indonesia has experienced the El Nino and La Nina climate anomalies with increasing frequency, duration, and level of strength.

Greenhouse warming and internal variability increase extreme and central Pacific El Niño frequency since 1980

El Niño has been recorded to change its properties since the 1980s, characterized by more common extreme El Niño and Central Pacific (CP) El Niño events. However, it is still unclear whether such change is externally forced or part of the natural variability. Here, we find that the frequency of the extreme and CP El Niño events also increased during the period 1875–1905, when the anthropogenic CO2 concentration was relatively lower, but with a positive phase of the Atlantic Multidecadal Oscillation (AMO). Models and palaeoclimate proxies reveal that a positive AMO enhances the zonal sea surface temperature gradient in the CP, which strengthens zonal advective feedback, favoring extreme and CP El Niño development. Moreover, we estimate that internal variability contributed to ~65% of the increasingly extreme and CP El Niño events, while anthropogenic forcing has made our globe experience ~1 more extreme and ~2 more CP events over the past four decades.

More frequent central Pacific El Niño and stronger eastern pacific El Niño in a warmer climate

El Niño events exhibit rich diversity in their spatial patterns, which can lead to distinct global impacts. Therefore, how El Niño pattern diversity will change in a warmer climate is one of the most critical issues for future climate projections. Based on the sixth Coupled Model Intercomparison Project simulations, we report an inter-model consensus on future El Niño diversity changes. Central Pacific (CP) El Niño events are projected to occur more frequently compared to eastern Pacific (EP) El Niño events. Concurrently, EP El Niño events are projected to increase in amplitude, leading to higher chances of extreme EP El Niño occurrences. We suggest that enhanced upper-ocean stability due to greenhouse warming can lead to a stronger surface-layer response for increasing positive feedbacks, more favorable excitation of CP El Niño. Whereas, enhanced nonlinear atmospheric responses to EP sea surface temperatures can lead to a higher probability of extreme EP El Niño.

Enhanced India‐Africa Carbon Uptake and Asia‐Pacific Carbon Release Associated With the 2019 Extreme Positive Indian Ocean Dipole

AbstractThe 2019 extreme positive Indian Ocean dipole drove climate extremes over Indian Ocean rim countries with unclear carbon‐cycle responses. We investigated its impact on net biome productivity (NBP) and its constituent fluxes, using the Global Carbon Assimilation System (GCASv2) product, process‐based model simulations from TRENDYv9, and satellite‐based gross primary productivity (GPP). By distinguishing two separate regions, the India‐Africa and Asia‐Pacific, GCASv2 indicated enhanced terrestrial carbon uptake of 0.23 ± 0.20 PgC and release of 0.38 ± 0.15 PgC, respectively, during September–December (SOND) 2019. These NBP anomalies had comparable magnitudes to those following the 2015 extreme El Niño which, however, caused the consistent carbon release in both regions. The TRENDYv9 model ensemble confirmed these NBP responses, albeit with smaller magnitudes. These regional NBP anomalies were related to soil moisture variations with a dominant role of GPP. Understanding the impact of IOD provides new insights into mechanisms driving interannual variations in regional carbon cycling.

The Essential Role of Westerly Wind Bursts in ENSO Dynamics and Extreme Events Quantified in Model “Wind Stress Shaving” Experiments

Abstract Westerly wind bursts (WWBs)—brief but strong westerly wind anomalies in the equatorial Pacific—are believed to play an important role in El Niño–Southern Oscillation (ENSO) dynamics, but quantifying their effects is challenging. Here, we investigate the cumulative effects of WWBs on ENSO characteristics, including the occurrence of extreme El Niño events, via modified coupled model experiments within Community Earth System Model (CESM1) in which we progressively reduce the impacts of wind stress anomalies associated with model-generated WWBs. In these “wind stress shaving” experiments we limit momentum transfer from the atmosphere to the ocean above a preset threshold, thus “shaving off” wind bursts. To reduce the tropical Pacific mean state drift, both westerly and easterly wind bursts are removed, although the changes are dominated by WWB reduction. As we impose progressively stronger thresholds, both ENSO amplitude and the frequency of extreme El Niño decrease, and ENSO becomes less asymmetric. The warming center of El Niño shifts westward, indicating less frequent and weaker eastern Pacific (EP) El Niño events. Removing most wind burst–related wind stress anomalies reduces ENSO mean amplitude by 22%. The essential role of WWBs in the development of extreme El Niño events is highlighted by the suppressed eastward migration of the western Pacific warm pool and hence a weaker Bjerknes feedback under wind shaving. Overall, our results reaffirm the importance of WWBs in shaping the characteristics of ENSO and its extreme events and imply that WWB changes with global warming could influence future ENSO.

Analisis Musim Tanam dan Pengaturan Pola Tanam Tanaman Pangan pada Berbagai Kondisi Curah Hujan di Daerah Amahai Kabupaten Maluku Tengah

Cropping patterning is an farming practice to obtain maximum production taking into account climatic conditions, soil and types of crops cultivated. This research, which was carried out in the Amahai Region, aimed to: (i) describe extreme climate events and (ii) determine the growing season and cropping patterns of food crops based on the length of the growing season available in the region. The analytical methods used consisted of: (i) determining extreme rainfall based on BMKG standards and ENSO History data, (ii) determining the planting season using the FAO method, and determining cropping patterns in conditions of extreme rainfall. The results showed that a very extreme El Nino event caused a decrease in rainfall in the Amahai region by 1,444 mm or 54% of its normal condition, on whereas a very extreme La Nina event caused an increase in rainfall by 1,528 mm or 60% of its normal condition. The growing season in the Amahai region under conditions of average (normal) and La Nina rainfall is throughout the year (12 months), and under conditions of extreme El Nino rainfall, the growing season lasts for 8 months and 26 days, 96 days shorter than normal conditions. In conditions of extreme El Nino rainfall, the cropping patterns that can be applied are sequential, monoculture, and polyculture/ intercropping.

Intensification and Dynamics of the Westward Equatorial Undercurrent During the Summers of 1998 and 2016 in the Indian Ocean

AbstractUsing mooring observations and reanalysis, we show that anomalously strong westward Equatorial Undercurrent (wEUC) developed in June–July in 2016 and 1998 in the Indian Ocean, which coincided with extreme Indian Ocean Dipole (IOD) and El Niño events. Simulations show that equatorial Kelvin and Rossby waves were excited by winds associated with El Niño and positive IOD events during 2015 and 1997, and their negative phases during 2016 and 1998. The constructive relationship between the delayed‐time contributions of eastern‐boundary‐reflected‐waves that excited by the easterlies in 2015 and 1997 and the direct contributions of wind‐forced‐waves that excited by the westerlies in 2016 and 1998 resulted in the intensified wEUC. Slow intermediate‐order baroclinic‐modes, rather than fast low‐order baroclinic‐modes, dominated the strong wEUC. The eastern‐boundary‐reflected‐waves dominated in 1997–1998 and directly wind‐forced‐waves dominated in 2015–2016. Our results emphasize the importance of constructive interactions of the directly‐wind‐forced and boundary‐reflected waves in driving the interannual variability of Indian Ocean wEUC.

Climate change can be seen through a disaster medicine lens.

Climate change can be seen through a disaster medicine lens.

A deep learning model for forecasting global monthly mean sea surface temperature anomalies

Sea surface temperature (SST) variability plays a key role in the global weather and climate system, with phenomena such as El Niño-Southern Oscillation (ENSO) regarded as a major source of interannual climate variability at the global scale. The ability to make long-range forecasts of SST variations and extreme marine heatwave events have potentially significant economic and societal benefits, especially in a warming climate. We have developed a deep learning time series prediction model (Unet-LSTM), based on more than 70 years (1950–2021) of ECMWF ERA5 monthly mean SST and 2-m air temperature data, to predict global 2-dimensional SSTs up to a 24-month lead. Model prediction skills are high in the equatorial and subtropical Pacific. We have assessed the ability of the model to predict SST anomalies in the Niño3.4 region, an ENSO index in the equatorial Pacific, and the Blob marine heatwave events in the northeast Pacific in detail. An assessment of the predictions of the 2019–2020 El Niño and the 2016–2017 and 2017–2018 La Niña show that the model has skill up to 18 months in advance. The prediction of the 2015–2016 extreme El Niño is less satisfactory, which suggests that subsurface ocean information may be crucial for the evolution of this event. Note that the model makes predictions of the 2-d monthly SST field and Nino 3.4 is just one region embedded in the global field. The model also shows long lead prediction skills for the northeast Pacific marine heatwave, the Blob. However, the prediction of the marine heatwaves in the southeast Indian Ocean, the Ningaloo Niño, shows a short lead prediction. These results indicate the significant potential of data-driven methods to yield long-range predictions of SST anomalies.

Intensification of ENSO frequency drives forest disturbance in the andes during the holocene

The biodiverse montane forests of the tropical Andes are today frequently disturbed by rainfall-driven mass movements which occur mostly during extreme El Niño events. Over the coming decades these events are projected to double under the 1.5 °C global warming scenario. The consequent increased rainfall and mass movement events likely present an elevated risk to millions of people living in the Andes. However, the impact of more frequent rainfall extremes remains unclear due to a lack of studies that directly link past changes in El Niño-Southern Oscillation (ENSO) frequency to forest and landscape disturbance patterns. Here, we present the first Holocene palaeoecological record from Laguna Pallcacocha, southern Ecuador, a key site for El Niño reconstructions. We demonstrate that for the past 10,000 years plant taxa indicative of recolonization – such as Alnus acuminata – covary with El Niño-induced flood layers in the lake. An amplified forest disturbance pattern is observed in the late Holocene, suggesting enhanced slope instability following deforestation. The temporal pattern is not explained by tree line fluctuations or human impact, while the latter does amplify the impact of ENSO on landscape disturbance. Spatial correlations between modern ENSO and precipitation are consistent with a regional comparison of Holocene records of landscape disturbance. Our results indicate that climate extremes, such as those associated with future intensification of El Niño, combined with ongoing land use change will increase the frequency of mass movements elevating risks for millions of people in the Andes.