The Current El Niño Phenomenon: An Overview
The recent El Niño phenomenon has dominated headlines in recent months, with various international organisations forecasting it to be the most intense event since 1950. This situation raises concerns that, in the coming months, the frequency and severity of rainfall and drought episodes may worsen globally. The World Meteorological Organization (WMO) confirmed in early September that El Niño is “firmly established” in the central and eastern equatorial Pacific, with expectations of further strengthening in the upcoming months, earning it the nickname “Super Niño” in several media outlets. According to the WMO, there is a nearly 100% probability that this event will persist until February 2027.
In light of this scenario, various international bodies, including the United Nations (UN), have urgently called for adaptation and mitigation measures to protect the welfare of both populations and ecosystems that could be adversely affected.
“A highly intense El Niño phenomenon, such as the one projected for this year, can significantly alter rainfall and temperature patterns worldwide, exacerbating extreme weather events,” warned the WMO.
Understanding El Niño: Definition and Mechanism
To comprehend the implications of El Niño, it is crucial to clarify what this phenomenon entails. El Niño refers to a condition characterised by higher-than-average sea surface temperatures in the equatorial Pacific, stretching from the International Date Line to the South American coast. This state typically persists for about a year and represents a natural climatic cycle in which accumulated ocean heat rises into the atmosphere, occurring every few years.
The National Oceanic and Atmospheric Administration (NOAA) in the United States determines whether an El Niño event is occurring by measuring the average sea surface temperature over three months in a region known as “Niño 3.4”. Their criteria include:
- A temperature 0.5 °C or more above the average for five consecutive periods, with one-month intervals between each.
- The expectation that this temperature anomaly will continue for five such periods.
- Changes in trade winds and precipitation patterns.
One of the defining characteristics of El Niño is the weakening of trade winds that typically blow from east to west, leading to a displacement of warm seawater towards the eastern tropical Pacific, resulting in a rise in sea level. Changes in sea surface temperature also affect atmospheric circulation, generating a chain reaction of climatic changes worldwide.
The Unprecedented Nature of the Current El Niño
José Martín Cortés, a meteorologist and atmospheric sciences graduate from Meteored Mexico, shared insights indicating that the current El Niño episode is particularly notable due to its forecasted intensity, which has not been observed since 1950. He highlighted the unusually rapid strengthening of the phenomenon, with NOAA’s Climate Prediction Centre projecting an anomaly of 2.6 °C above normal, compared to an earlier measurement of 2 °C in early September. If this forecast holds true, it would slightly surpass the records set during the most intense episodes documented: 2.4 °C in 1982-1983 and 2.3 °C during the events of 1997-1998 and 2015-2016.
Cortés cautioned that prior to 1950, there was insufficient instrumentation to monitor such phenomena, which raises the possibility that similarly intense events occurred in previous centuries. He emphasised that the current global population density significantly influences the positive or negative effects attributed to El Niño.
Climate Context: A Distinct Scenario
Francisco Estrada, head of the Climate Change Research Programme at the National Autonomous University of Mexico (UNAM), added that the current El Niño is occurring amidst a markedly different climatic context compared to previous decades. Currently, global temperatures are approximately 1.46 °C above pre-industrial levels. In early September, the United Nations Environment Programme (UNEP) predicted that the planet would inevitably exceed the 1.5 °C global warming limit set in the Paris Agreement, potentially before the end of this decade.
As a result, Estrada underscored that “global warming has altered the characteristics and patterns of extreme weather events associated with El Niño, placing us at significant risk. One can no longer rely on historical data to predict El Niño’s impact on weather and climate across different regions of the world.”
Assessing the Role of Climate Change
Amidst these forecasts, the debate intensifies: Is the current El Niño’s unusual rapidity and intensity a direct outcome of climate change, or is it merely a natural phenomenon exacerbated by the sheer number of people on the planet? Cortés contended that there is currently insufficient evidence to establish a direct link between the climate crisis and the unusual intensity of the present El Niño episode. He argued that more data is required to determine if these phenomena are becoming increasingly intense and frequent as a result of climate change.
“At this point, [this connection] is a speculation or possibility, but it has not been thoroughly studied because this is the first phenomenon in recent decades with these characteristics. We must proceed with caution,” he stated.
The meteorologist explained that establishing this connection necessitates attribution studies, which compare models and simulations to ascertain what might have occurred with a given phenomenon on a planet without global warming effects versus a warmer planet. However, he cautioned that these simulations have limitations and cannot be considered conclusive evidence, as the existence, intensity, and frequency of various events are not uniformly represented in these projections.
Scientific Perspectives on Climate Change and El Niño
While acknowledging the likelihood that El Niño’s impacts may be intensified by climate change, Cortés also asserted that the planet inherently seeks equilibrium, which he believes will ultimately counteract the warming induced by human activities. “Currently, we are warming the planet for various reasons. Scientists argue that there is no turning back. However, the planet seems to disagree: despite significant warming and high levels of carbon dioxide, it has ultimately cooled and regulated itself,” Cortés explained.
He continued, “Meteorologically, it is understood that our planet constantly aims for balance. Regardless of global warming or extreme phenomena, there will eventually be a counteraction to regulate those effects. Thus, one cannot confidently assert that similar events have not occurred in previous centuries or millennia; the only certainty is that there was no population to document such occurrences.”
The Importance of Continued Research
Francisco Estrada concurred on the necessity for further research to establish whether climate change directly influences the intensity forecasted for the current El Niño. Nevertheless, he noted that peer-reviewed studies indicate that the variability of El Niño has increased over the past 60 years, with more significant events occurring. He added that there is scientific evidence that global warming is altering the characteristics of El Niño, including its amplitude, frequency, and the distribution of its effects globally. Therefore, Estrada contended that the debate should not be framed as a choice between “natural El Niño” and “climate change-induced El Niño,” but rather as an interaction between both processes.
“You cannot detach El Niño from the aspect of global warming; they are intrinsically linked,” he explained. Thus, from a risk perspective, he found it more relevant to understand how these two phenomena interact and how this combination will affect societies.
Consequently, Estrada’s primary concern is not solely whether this El Niño will be the most intense on record, but rather the combination of an exceptional natural phenomenon with a climate that has already undergone significant changes. This interaction could lead to unexpected behaviours and heighten risks associated with precipitation, drought, extreme temperatures, hurricanes, water availability, and other impacts. “The last thing one desires when managing risk is surprises,” he concluded.