In a groundbreaking new study, climate scientists have unveiled a complex but consequential teleconnection linking delayed warming in the Southern Ocean (SO) to intensified precipitation patterns over some of the world’s most climatically vulnerable regions, including East Asia, the western United States, and the southeastern United States. This research not only exposes the intricate pathways through which the Southern Ocean impacts global climate but also sheds light on persistent regional hydrological changes under future anthropogenic warming scenarios. The findings, published in Nature Geoscience, have far-reaching implications for understanding climate variability and improving long-term regional climate projections.
The Southern Ocean, encircling Antarctica, plays a critical yet often underappreciated role in regulating Earth’s climate system due to its vast capacity to absorb and store heat from the atmosphere. Unlike many other ocean basins, the SO is characterized by its unique ocean-atmosphere interactions and distinct low cloud feedback mechanisms, which combine to produce a highly lagged warming response to increasing greenhouse gases. This delayed warming—occurring over centennial timescales—triggers a far-reaching teleconnection pattern that ultimately culminates in enhanced warming across the equatorial Pacific Ocean, exhibiting an El Niño-like climate signature.
Central to this teleconnection is the slow propagation of heat anomalies from the Southern Ocean toward the equator. These anomalies preferentially travel westward, guided by prevailing southeasterly trade winds, which channel the warming signals along climatological pathways just west of continental landmasses. This journey is further reinforced by a positive feedback loop involving Southern Hemisphere low clouds: as the SO warms, changes in cloud cover amplify local warming, thus intensifying and sustaining the heat signal as it migrates northward.
Once the warming reaches the equator, its impact escalates substantially. Here, the ocean-atmosphere system engages the Bjerknes feedback, a powerful positive feedback process named after the Norwegian meteorologist Jacob Bjerknes. This dynamic interplay between sea surface temperatures, wind stress, and thermocline depth amplifies the initial warming, establishing an El Niño-like pattern characterized by anomalously warm waters in the tropical Pacific. Such a regime profoundly influences atmospheric circulation and global weather patterns.
Seasonal shifts further modulate the climate impacts of this teleconnection. During boreal summer, the enhanced equatorial warming heats the tropical troposphere along the moist adiabat—the rate at which atmospheric temperature decreases with height under saturated conditions. This heating promotes a southerly shift in the Asian jet stream. The repositioning of this jet intensifies its interaction with the Tibetan Plateau, strengthening regional ascending motions and consequently elevating precipitation levels over East Asia. This mechanistic link clarifies observed and predicted trends in monsoonal rainfall intensity under climate change.
In boreal winter, the consequences of the El Niño-like warming pattern extend across the Northern Hemisphere mid-latitudes. The altered thermal gradients generate Rossby wave responses, facilitating the development of a Pacific-North America (PNA) atmospheric circulation pattern. This pattern consists of alternating high and low pressure anomalies that modulate storm tracks and moisture transport. The resulting dynamics bring increased precipitation to both the western and southeastern United States, regions historically vulnerable to drought and hydrological extremes. Thus, the delayed Southern Ocean warming indirectly influences water resources and climate risk in these critical areas.
The study underscores the pivotal role of Southern Hemisphere low cloud feedbacks in regulating this teleconnection’s strength, which importantly varies among climate models. These feedbacks affect how efficiently the Southern Ocean warms and how the teleconnection signal propagates to lower latitudes. Uncertainty in low cloud dynamics thus emerges as a leading factor contributing to inter-model discrepancies in regional precipitation forecasts and overall climate sensitivity estimates. This insight invites renewed scientific focus on better representing these feedbacks in Earth system models.
Recent field campaigns aimed at comprehensively observing Southern Hemisphere low clouds promise to address these uncertainties. By integrating specialized observations into model development, researchers expect not only to refine projections of global average temperature change but also to achieve more dependable regional climate predictions. Enhanced understanding of Southern Ocean cloud feedbacks holds immense potential for narrowing the range of future climate scenarios, enabling more actionable climate policy and planning.
Importantly, the delayed Southern Ocean warming and its teleconnections manifest primarily over centennial timescales, implying limited influence on near-future transient climate projections. This temporal dimension means that future warming signals in other ocean basins may appear earlier, with the Southern Ocean acting as a slow but persistent climate driver. Moreover, as global greenhouse gas emissions are curtailed and atmospheric CO2 concentrations stabilize or decline, the Southern Ocean’s thermal inertia will allow it to remain anomalously warm even as other regions cool or equilibrate more rapidly.
Novel simulations from the Carbon Dioxide Removal Model Intercomparison Project (CDRMIP) vividly illustrate these dynamics. In these experiments, atmospheric CO2 is transiently quadrupled and subsequently removed, representing an ambitious carbon dioxide removal scenario. During the CO2 reduction phase, the Southern Ocean maintains elevated sea surface temperatures, which uphold tropical Pacific warming patterns akin to those seen during the initial increase. Correspondingly, regional precipitation enhancements over East Asia and the United States persist despite declining greenhouse gas concentrations, indicating a long-term commitment to altered hydrological regimes driven by SO thermal inertia.
The persistence of warming and increased precipitation implicates a profound challenge for climate adaptation and mitigation strategies. Policymakers and planners must account for these slow-evolving but enduring regional climate changes that will continue to reshape water availability, agriculture, infrastructure resilience, and ecosystem services—even should global emissions be drastically reduced. The prospect of lingering Southern Ocean-forced climate signals necessitates a reevaluation of expectations for timing and intensity of regional climate change impacts.
In addition to future projections, the Southern Ocean also emerges as a key pacemaker for recent climate trends documented over the past few decades. Observational studies and model hindcasts reveal that accurate simulation of SO cooling trends improves forecast skill for tropical Pacific sea surface temperatures and precipitation patterns across the western and southeastern United States. This finding bridges a crucial gap in connecting Southern Ocean processes with regional climate variability and extremes, offering a target for model improvement.
In practical terms, increasing model resolution over the Southern Ocean enhances prediction accuracy, especially on decadal scales. Such improvements hold promise for more reliable seasonal and interannual forecasts of hydroclimatic conditions in regions profoundly affected by the SO-driven teleconnection, which is critical for water resource management and disaster preparedness. The study’s mechanistic framework thus provides actionable avenues for enhancing climate model fidelity and operational forecasting.
Collectively, these revelations underscore the Southern Ocean’s underestimated influence as a slow but powerful hub of global climate variability. By modulating equatorial warming and atmospheric circulation patterns, its delayed response to anthropogenic forcing orchestrates significant and enduring changes in precipitation regimes far beyond its immediate vicinity. Capturing these dynamics in climate models is indispensable for refining regional climate projections, guiding adaptation, and assessing climate sensitivity.
As Earth’s climate system continues to respond to human activities, the Southern Ocean teleconnection elaborated in this research highlights the necessity of integrating slow oceanic processes, cloud feedbacks, and atmospheric dynamics in a holistic framework. This integrated understanding not only elucidates the complexity of climate responses but also charts a clearer path toward mitigating uncertainty and bolstering societal resilience in the face of evolving hydroclimate risks.
In summary, the delayed warming of the Southern Ocean is not a distant or isolated phenomenon—it is a global climate game-changer with far-reaching and persistent effects on precipitation and atmospheric circulation. Recognizing and accounting for this influence is critical for advancing climate science, improving predictive capabilities, and ultimately securing more effective climate action worldwide.
Subject of Research:
The study investigates the climatic teleconnection between delayed Southern Ocean warming under anthropogenic climate change and enhanced regional precipitation in East Asia and the United States through El Niño-like equatorial warming patterns.
Article Title:
Higher precipitation in East Asia and western United States expected with future Southern Ocean warming.
Article References:
Kim, H., Kang, S.M., Pendergrass, A.G. et al. Higher precipitation in East Asia and western United States expected with future Southern Ocean warming. Nat. Geosci. 18, 313–321 (2025). https://doi.org/10.1038/s41561-025-01669-5
Image Credits:
AI Generated
DOI:
https://doi.org/10.1038/s41561-025-01669-5
Keywords:
Southern Ocean warming, climate teleconnection, El Niño-like pattern, equatorial Pacific warming, low cloud feedback, Bjerknes feedback, Asian jet stream shift, Pacific-North America (PNA) pattern, regional precipitation change, CMIP6, climate sensitivity, carbon dioxide removal, climate model projections
