2025 Shatters Heat Records, Defying La Niña Cooling
Overview
Global temperatures soared in 2025, marking the third warmest year on record and the hottest La Niña year ever observed by Berkeley Earth. Despite the typically cooling influence of La Niña, 9.1% of Earth's surface experienced record heat, impacting millions primarily across Asia. This trend challenges past warming rate predictions.
2025 Smashes Heat Records Amidst La Niña
Global temperatures in 2025 reached unprecedented levels, culminating in the third warmest year on record. This occurred despite the presence of La Niña conditions for significant portions of the year, a weather phenomenon typically associated with global cooling. Berkeley Earth's Annual Temperature Report 2025 reveals that 2025 stands as the warmest year on record during a La Niña phase, underscoring a dramatic departure from expected climate patterns.
La Niña, the cooler phase of the El Niño Southern Oscillation (ENSO) in the Equatorial Pacific, began in December 2024 and persisted until March 2025. After a brief neutral period, it re-emerged in September 2025 and remains prevalent, though rapidly weakening. Scientists anticipate a transition towards El Niño conditions by summer 2026. Nevertheless, even with these cooling influences, the global average annual temperature anomaly reached a striking 1.44°C. This figure places 2025 behind only 2024 and 2023 in terms of overall global warmth.
Widespread Record Heat Affects Millions
The report detailed the alarming extent of extreme heat experienced globally. Approximately 9.1% of Earth's total surface registered its highest annual average temperature in 2025. Breaking this down, 10.6% of land areas and 8.3% of ocean areas endured record-breaking warmth. Crucially, these record heat zones overlapped with major population centers. Berkeley Earth stated that "Roughly 770 million people (8.5% of the global population) experienced record warm annual temperatures, primarily in Asia." Significantly, no regions globally recorded a record cold year, highlighting the pervasive nature of the warming trend.
Shifting Warming Trajectories
This finding aligns with observations from other climate monitoring services, such as the Copernicus Climate Change Service (C3S), which notes that the last eleven years include all eleven of the warmest years ever recorded. The last three years, in particular, constitute the three warmest. The report emphasizes a concerning acceleration: "The warming spike in 2023 to 2025 suggests that the past warming rate is no longer a reliable predictor of the future, and additional factors have created conditions for faster warming, at least in the short-term." This suggests that the Earth's climate system may be responding to warming drivers in ways that are more rapid and less predictable than previously modeled.
