by Daniel Brouse
May 10, 2025
The lingering effects of this past winter’s La Niña are rapidly diminishing, with the tropical Pacific climate now settling into ENSO-neutral conditions. Sea surface temperatures (SSTs) in the central equatorial Pacific are currently only slightly below average, and key atmospheric indicators—such as trade winds and convection patterns—still show faint La Niña characteristics. However, these atmospheric signs are weakening sharply.
This recent La Niña ranks among the shortest and weakest on record. While ENSO events (El Niño–Southern Oscillation) naturally fluctuate, the unusual brevity and mildness of this La Niña have sparked further scrutiny among climate scientists. One emerging hypothesis is that broader disruptions in global ocean circulation may be affecting traditional ENSO patterns.
In particular, mounting evidence suggests that the Atlantic Meridional Overturning Circulation (AMOC)—a major system of ocean currents that transports warm water from the tropics northward in the Atlantic—may be approaching or has already crossed a critical tipping point. The AMOC plays a vital role in regulating global climate, and its weakening or collapse would have far-reaching and catastrophic consequences. These could include intensified heatwaves in Europe, more frequent droughts in the Amazon, disrupted monsoons in West Africa and South Asia, rising sea levels along the U.S. East Coast, and further destabilization of polar ice sheets.
While a direct causal link between the current ENSO behavior and AMOC weakening remains uncertain, both phenomena point to the broader destabilization of Earth’s climate systems driven by human-induced global warming. Climate models have long warned that once critical thresholds are crossed, feedback loops and cascading impacts could accelerate dramatically. We may now be witnessing the early stages of such a cascade. In fact, our updated climate model indicates that changes previously expected to unfold over millennia are now occurring within mere decades—highlighting the urgent need for rapid emissions reductions and robust climate adaptation strategies.