El Niño’s Onset and Global Implications

El Niño under way and threatens – US scientists have confirmed the arrival of El Niño, a natural climate phenomenon that influences weather patterns across the Pacific. The National Oceanic and Atmospheric Administration (NOAA) declared that the warming phase has officially begun, citing a noticeable rise in sea surface temperatures in the central and tropical Pacific. This development follows the conclusion of a cooler La Niña event earlier this year, which had temporarily dampened global temperatures. While the transition to El Niño was anticipated, the intensity of the current event has raised concerns about its potential to amplify extreme weather conditions and push temperatures to new records.

NOAA’s Confirmation and Model Predictions

According to NOAA, the tropical Pacific has crossed a critical threshold, with sea surface temperatures surpassing the 0.5C-above-average mark used to identify El Niño. The agency emphasized that the shift in atmospheric conditions—specifically the weakening of trade winds over the equatorial region—is a key indicator of the event’s progression. This atmospheric response to the warmer ocean underscores the interconnectedness of climate systems, as wind patterns and sea temperatures influence each other in a dynamic feedback loop.

“El Niño conditions developed over the past month, as shown by above-average sea surface temperatures (SSTs) across the central to eastern equatorial Pacific Ocean,” said NOAA. The agency also highlighted the growing confidence in computer models, which predict the event could reach very strong levels by the end of the year. While some models suggest temperatures in the tropical Pacific might rise more than 3C above the long-term average, the US agency cautioned that these projections should be interpreted with care.

Historical Comparisons and Future Projections

El Niño’s strength is determined by how much sea surface temperatures exceed the historical norm in a specific zone of the Pacific. A very strong event is defined as temperatures rising above 2C, a standard that could be met in the coming months. The three most intense El Niño occurrences since 1950 were in 1982/83, 1997/98, and 2015/16, each contributing to record-breaking global temperatures. If the current event matches or exceeds these benchmarks, it may have profound consequences for the planet’s climate.

NOAA’s June outlook indicated a 63% probability of a very strong El Niño during November-January, positioning it as one of the largest on record. This projection is supported by both US and European climate models, which suggest the event could intensify further. However, the agency stressed that the strength of El Niño alone does not guarantee specific weather outcomes, as its effects are moderated by other factors, including long-term human-driven climate change.

Interactions with Human-Induced Warming

The current El Niño is occurring against a backdrop of a planet already experiencing significant warming. As Professor Adam Scaife of the UK Met Office noted, “We do need to worry about the impacts” of this combination. The natural warming from El Niño is叠加 on top of the existing global heating, potentially leading to unprecedented heat levels in affected regions. Even the relatively modest El Niño of 2024, which contributed to the warmest year on record, demonstrated the phenomenon’s power in a world with pre-existing climate stressors.

“The current El Niño is… riding on top of a substantial amount of global warming,” Scaife added. “This means that the actual temperatures in affected regions could well be unprecedented, as the warming from El Niño is being topped up by climate change.” The implications of this叠加 are far-reaching, with the potential to disrupt ecosystems, food supplies, and economic systems well into 2027.

Regional Weather Disruptions

El Niño’s effects are most pronounced in the tropics, where it typically triggers a range of extreme weather events. In northern Peru and southern Ecuador, heavy rainfall and flooding are common, with the risk extending to East Africa, Central Asia, and parts of the southern United States. Conversely, regions like Australia, Indonesia, and northern South America face heightened drought and wildfire risks, which threaten agricultural production and global food reserves. These regional impacts highlight the variability of El Niño’s influence, as it can simultaneously bring both deluge and aridity to different parts of the globe.

Meanwhile, the Atlantic hurricane season is expected to be quieter than usual, a trend linked to El Niño’s ability to suppress tropical cyclone formation. While this might seem beneficial for some areas, it could lead to reduced rainfall in Central America, increasing the risk of drought. “While that sounds like a good thing, for Central America that leads to a lot less rainfall and potentially drought conditions,” explained Liz Stephens, a professor at the University of Reading specializing in climate risk and resilience.

Broader Climate Impacts

El Niño’s influence extends beyond immediate weather patterns, shaping long-term climate trends. A very strong event can elevate global air temperatures by approximately 0.2C, adding heat to a world already warming due to human activities. Despite the cooling effects of La Niña in 2025, that year still ranked as the third warmest on record, underscoring the dominance of climate change over natural variability. If the current El Niño reaches its full potential, it could surpass the temperature records of 2016, a year marked by a super El Niño, and trigger another year of extreme heat.

Prof Scaife warned that the prolonged period of warming could lead to global temperatures exceeding 1.5C above pre-industrial levels by 2027. This threshold, defined as the warming observed since the late 19th century, is critical for limiting the worst impacts of climate change. Even without the additional heat from El Niño, 2025’s temperatures were already pushing the boundaries of what is considered “normal” in a rapidly warming world.

El Niño’s Role in a Warming World

Although no two El Niño events are identical, their combined effects with human-induced climate change are becoming more predictable. The phenomenon is not just a seasonal fluctuation but a key driver of global climate variability. In the UK, for example, El Niño is sometimes associated with a mild start to winter and a colder finish, though the connection is not always consistent. This illustrates how even regions outside the Pacific can experience indirect climate impacts.

The ongoing El Niño adds to the complexity of forecasting future climate scenarios. As scientists continue to monitor the event, they recognize its potential to accelerate climate change’s effects. “An El Niño can tilt the odds in favour of expected outcomes,” Scaife said, though he acknowledged that the outcomes themselves—such as record temperatures, altered precipitation patterns, and extreme weather events—could vary depending on the interplay of natural and human factors. The current phase of the climate cycle, therefore, is a critical test of how well the global community can adapt to an increasingly unstable environment.

Conclusion and Outlook

With El Niño now in full swing, the focus is on its potential to compound the challenges posed by climate change. The combination of a strong El Niño and a hotter baseline climate could lead to a cascade of environmental and socioeconomic disruptions. From severe flooding in South America to droughts in Southeast Asia, the event’s reach is global. As NOAA and other climate agencies refine their models, the urgency to mitigate greenhouse gas emissions and prepare for extreme weather conditions has never been greater. The coming years will likely serve as a barometer for the planet’s resilience in the face of escalating climate pressures.