The tropical Pacific has experienced significant heat buildup as a super El Niño develops. This climate phenomenon, which occurs every few years, is expected to reach unprecedented strength this winter, characterized by hotter-than-normal waters in the eastern tropical Pacific. El Niño is recognized as a global issue.
The interaction between El Niño and climate change, driven by fossil fuel emissions, is a topic of ongoing research. Christopher Callahan, a climate researcher at Indiana University, expressed uncertainty about the relationship, stating, "I have more questions than I have reactions" regarding the current situation. This year's event may provide critical insights into this interaction.
El Niño's increased ocean heat influences atmospheric conditions, causing global weather patterns to shift. The U.S. National Oceanic and Atmospheric Administration (NOAA) has forecasted a 100 percent chance of an extremely strong El Niño through December, with over 80 percent likelihood of it continuing into February. Data indicates that this El Niño has already set multiple daily heat records, including a recent peak of 3.4 degrees Celsius.
NOAA's El Niño forecast is based on a three-month rolling average, predicting a peak heat increase of 2.7 degrees Celsius above normal from October to December, potentially exceeding 3 degrees Celsius. If accurate, this would surpass the previous record of 2.4 degrees Celsius set during the 1982-1983 event.
Evidence suggests that climate change may influence El Niño's intensity and frequency, with Francisco Estrada, coordinator of the Climate Change Research Program at the National Autonomous University of Mexico, stating that the two processes should not be viewed in isolation. He emphasized that "You can’t separate El Niño from global warming—they’re inextricably linked."
Modeling indicates that El Niño may strengthen as global temperatures rise, although Callahan noted that many models struggle to accurately represent long-term temperature trends in the eastern tropical Pacific. He mentioned that the majority of climate models predict an increase in El Niño amplitude in a warming climate, supported by paleoclimate records indicating a more active El Niño period than in the last 1,000 years.
Research published in August utilized ancient coral data to examine El Niño amplitude over the past millennium, revealing an increase that correlates with the onset of human-induced greenhouse gas emissions, although the study did not directly attribute the change to climate change.
This year's El Niño will serve as an additional data point for researchers. Callahan raised concerns about how El Niño interacts with climate change, noting that even if the event's intensity is not directly influenced by climate change, the altered climate may lead to unprecedented impacts.
El Niño's weather impacts, known as teleconnections, are well-documented, affecting drought likelihoods in regions like the Amazon and Indonesia, increasing precipitation in the Southwestern U.S., and reducing Atlantic hurricane probabilities. However, the combination of an extreme El Niño and climate change may intensify these effects.
Estrada cautioned that reliance on historical data regarding El Niño's weather manifestations may be diminished due to the changing climate. Fishermen in the eastern Pacific are already experiencing the effects of El Niño, with species migrating to deeper waters, resulting in reduced catches.
Understanding the interaction between El Niño and climate change is crucial for assessing societal impacts. Estrada and Callahan are concerned not only about the potential intensity of this El Niño but also about the implications of an extraordinary event occurring in a significantly warmed climate. Estrada stated, "Surprises are the last thing you want when you’re trying to manage risk."
Callahan's research indicates that El Niño can have severe economic impacts, potentially reducing global GDP by trillions of dollars and causing significant harm to ecosystems, particularly coral reefs, which are facing mass bleaching events. In response to these challenges, the United Nations and other organizations have called for urgent adaptation measures to protect vulnerable populations and ecosystems. California has already declared a state of emergency in anticipation of the impacts.
UN Secretary-General António Guterres remarked, "El Niño conditions will pour fuel on the fire of a warming world. Impacts will hit even harder, travel even farther, and cross borders with devastating speed."