In the consecutive years of 2023 and 2024, Earth experienced an extraordinary surge in average global surface temperatures, escalating by nearly 0.3 degrees Celsius beyond the projections established by existing climate models. This marked deviation from expected warming trends resulted in these years being officially recorded as the hottest ever observed, a phenomenon that coincided with devastating wildfires, unprecedented heat waves, and an alarming proliferation of climate-induced disasters worldwide. These anomalies posed a formidable challenge to climatologists striving to dissect the underpinning forces that propelled such severe thermal deviations.
A groundbreaking study published on May 6, 2026, in the journal Earth System Dynamics by researchers at the University of Maryland introduces a compelling explanation for these anomalous temperature spikes. The team highlights the Indian Ocean Dipole (IOD), a relatively underexplored climatic oscillator analogous to the Pacific’s El Niño, as a pivotal contributor to the extreme warmth experienced in these years. This research marks the inaugural instance wherein the IOD is explicitly linked to the extreme heat events of 2023 and 2024, suggesting its significant global climatic influence has been previously underestimated.
The researchers developed an advanced climate modeling framework that integrates a comprehensive array of both anthropogenic and natural forcings to predict global surface temperature anomalies with unprecedented accuracy. Their simulation accounted for approximately 93% of the observed temperature anomaly in 2023 and 92% in 2024, signifying the closest approximation to date in attributing these temperature records. Intriguingly, the Indian Ocean Dipole emerged as one of the most consequential predictors within this model. Removal of the IOD-related variables precipitated a dramatic reduction in explanatory power, dropping to 69% for the 2023 anomaly and 77% for 2024, underscoring the critical role of this ocean-atmosphere interaction in recent global warming trends.
Endre Farago, the study’s lead author and former doctoral candidate at the University of Maryland, emphasized the magnitude of their achievement. “Our model’s ability to elucidate over 90% of the anomaly is practically unprecedented in climate attribution science,” he remarked. This revelation sheds new light on the complexity of climate drivers, indicating that previously overlooked natural oscillations can exacerbate or modulate the warming trajectory driven by human activities.
The Indian Ocean Dipole represents a variability pattern characterized by fluctuations in sea surface temperatures between the western and eastern sectors of the Indian Ocean. These thermal contrasts affect large-scale atmospheric circulation, inducing shifts in monsoon dynamics over South Asia and altering precipitation patterns across continents, from Australia’s fire-prone regions to the humid zones of Africa. Historically, the IOD’s discovery in the late 1990s underscored its novelty in climate science, and its intricate relationship with the more prominent El Niño-Southern Oscillation (ENSO) phenomenon remained a subject of debate for over a decade.
Notably, the Indian Ocean’s relatively smaller expanse compared to the Atlantic and Pacific ocean basins contributed to early skepticism regarding its global climate influence. Ross Salawitch, a co-author and atmospheric scientist with joint appointments at University of Maryland’s Department of Chemistry and Biochemistry and the Earth System Science Interdisciplinary Center, recounted the initial scientific hesitancy. “For years, the Pacific was deemed the ‘dog’ driving global climate variability, while the Indian Ocean was regarded as the ‘tail’, incapable of exerting substantial influence,” he explained. This study challenges that paradigm, demonstrating the IOD’s capacity to shape planetary temperature anomalies meaningfully.
Farago’s initial hypothesis met with cautious skepticism from Salawitch. However, the distinct warming patterns they identified over South America and southern Australia during the anomalous years, patterns not adequately explained by ENSO alone, validated the significance of the IOD’s role. Additionally, the model’s impaired performance when excluding the IOD reinforced their conclusion, illustrating the oceanic cycle’s integral function in modulating global temperature extremes.
Prior comprehensive investigations, including one by the World Meteorological Organization, failed to adequately explain the temperature surge, notably in 2023, which coincided with one of the most intense IOD episodes recorded since systematic global measurements began in the mid-19th century. These earlier studies omitted the IOD, highlighting a critical gap in the collective scientific understanding of natural climate variability and its interaction with anthropogenic factors.
Beyond the Indian Ocean Dipole, the study also quantified the contributions of other natural cycles such as elevated North Atlantic sea surface temperatures and Pacific ENSO events that modulated global climate patterns during these years. Remarkably, the IOD’s influence on global temperatures was on par with ENSO during 2023 and roughly half as significant in 2024, reinforcing the Indian Ocean’s emergent role as a driver of planetary warming.
While these natural oscillations partially elucidate the anomalous warmth, the study unequivocally affirms the persistent and accelerating influence of human-generated greenhouse gas emissions. The data reveal an anthropogenic warming rate approximating 0.022 degrees Celsius per annum in 2023 and 2024, a marked acceleration relative to trends observed during the late 20th century, highlighting the inexorable anthropogenic acceleration of climate change.
An additional, subtler anthropogenic impact unveiled by the study pertains to the 2020 International Maritime Organization regulation targeting reductions in sulfur oxide emissions from shipping fuel. Although these pollutants are harmful to human health, their atmospheric presence exerts a cooling influence by reflecting solar radiation. As sulfur emissions decreased, a consequential unintended effect was an increase in absorbed solar radiation—this “clean shipping” effect contributed an estimated warming equivalent to 25% to 30% of that caused by elevated greenhouse gases during the years in question. The study postulates that these regulatory measures may have also amplified the anomalous warming in the North Atlantic, coupling environmental policy with regional climate forcings.
Despite the nominal magnitude of a 0.3-degree Celsius anomaly, the researchers emphasize its profound climatological and societal implications. Representing approximately 20% of the total anthropogenic warming recorded since 1850, such anomalies exacerbate climate extremes including intensified heat waves and precipitation anomalies, thereby amplifying risks to public health, infrastructure, and ecosystems. This underscores the pressing necessity for precise attribution of climate drivers to inform targeted mitigation and adaptation policies.
The authors advocate for the integration of the Indian Ocean Dipole into contemporary climate models to refine projections and attribution studies. Salawitch expressed optimism that this research would catalyze rigorous scientific dialogue, fostering recognition of the IOD’s critical role in global warming assessments. “Acknowledging the IOD in future analyses will enhance the quantification of both natural and anthropogenic warming influences, crucial for devising informed climate policy frameworks,” he stated.
This landmark study, titled “Quantification of the influence of anthropogenic and natural factors on the record-high temperatures in 2023 and 2024,” represents a pivotal advancement in the interdisciplinary field of climate analytics. It exemplifies the importance of coupling observational data with sophisticated computational modeling to unravel the complex interplay of forces shaping Earth’s climate system amid ongoing anthropogenic pressures.
Subject of Research: Not applicable
Article Title: Quantification of the influence of anthropogenic and natural factors on the record-high temperatures in 2023 and 2024
News Publication Date: 6-May-2026
Web References:
- World Meteorological Organization report (https://wmo.int/sites/default/files/2025-03/WMO-1368-2024_en.pdf)
References:
- Earth System Dynamics, May 6, 2026, University of Maryland research on IOD and climate attribution
Keywords:
Indian Ocean Dipole, IOD, global warming, climate change attribution, anthropogenic influence, sea surface temperatures, El Niño-Southern Oscillation, ENSO, climate modeling, greenhouse gas emissions, marine sulfur emissions, atmospheric science
