El Niño 2024: NOAA Scientist Explains a Potential Super El Niño and Global Weather Impacts

Overview

In this Science Friday episode, Ira Flatow chats with Dr. Dylan Amaya of the NOAA Physical Sciences Laboratory about El Niño, the possibility of a super El Niño this year, how it forms, and why it matters for weather and ecosystems around the world. The discussion covers the mechanics of trade winds, how a warming eastern Pacific reshapes rainfall and jet streams, and the potential benefits and risks of a very strong El Niño for regions from the American Southwest to Australia and the Sahel.

• What El Niño is and how it is measured, including the warming of the eastern equatorial Pacific and its place in the ENSO cycle with La Niña.
• What makes this year a candidate for a super El Niño and the subsurface ocean heat content that can trigger rapid, large-scale changes.
• Predicted odds and uncertainties about strength and timing, with a fall timeframe for official declarations.
• Global weather and ecological implications, including wetter conditions in parts of the U.S. Southwest and the risk of marine heat waves and coral bleaching.

Introduction and context

The podcast opens with Ira Flatow introducing the topic of El Niño and noting that climate models suggest a significant El Niño year ahead, potentially a super El Niño. He speaks with Dr. Dylan Amaya, a research scientist at the NOAA Physical Sciences Laboratory in Boulder, Colorado. The host asks for a refresher on El Niño, and Amaya defines it as a warming of the eastern equatorial Pacific that is typically measured as an increase of more than about 0.5°C in five consecutive three-month averages. The discussion emphasizes that El Niño events occur on a cycle roughly every three to five years and are often paired with La Niña, the cooler phase of the El Niño Southern Oscillation, highlighting the broader climate system at play. The conversation also touches on how climate change is studied in this context, noting that each El Niño is warmer than the last, driven by global warming, though the exact influence on frequency remains an active area of research.

What makes this year potentially a super El Niño

Amaya explains that the term “super El Niño” is used when the event is unusually large, with expectations that the ocean-atmosphere system could warm by as much as 2°C above normal in the affected region. This magnitude would produce noticeable atmospheric and climate system changes globally, even if individual land temperatures might not feel dramatic. The discussion clarifies that the distinction lies in the strength and the resulting signal in climate patterns rather than a dramatic, immediate weather phenomenon.

Both participants stress the difference between an El Niño and a weather storm; El Niño is a climate-scale shift rather than a single meteorological event, complicating public understanding when media often emphasizes storms rather than long-term climate shifts.

Mechanisms behind ENSO and the role of wind and heat content

The core mechanism of El Niño is then explored: normal trade winds transport warm surface water toward the western Pacific. If these winds relax for extended periods, warm water can slosh back to the eastern Pacific, elevating temperatures there and altering atmospheric circulation and precipitation patterns. Amaya highlights the subsurface ocean heat content as a key factor in the development of a strong El Niño. Accumulated heat beneath the surface can be released as wind patterns relax, creating a large and sustained warming event. The models’ current projections place the odds of a very strong, strong, or moderate El Niño developing this summer into fall at about 25%. He notes that as climate models improve, confidence increases that an El Niño is on the horizon, but the exact strength remains uncertain.

Forecast confidence and timing

Flatow asks when the models might firm up their predictions. Amaya responds that there is high confidence (80% to 100%) that El Niño will occur, but the strength and exact timing are still being resolved. He suggests that another month or two of data and model convergence will help the community settle on a more definitive strength category. In terms of an arrival date, Amaya explains that El Niño is not a weather pattern with a fixed date; it is a gradual transition that is typically officially declared in the fall.

The mechanics of ENSO and broader climate dynamics

The discussion then returns to the normal state of the equatorial Pacific, elaborating on the interplay of ocean dynamics and atmospheric processes. The trade winds’ westward push drives warm water to the western Pacific near Indonesia, while a relaxation of these winds lets warm water return toward the coast of Peru. The ensuing temperature anomalies induce atmospheric waves and influence global storm tracks, including shifts in the jet stream that can alter the regionally specific weather patterns across the United States, and even reach to the East Coast. The host and guest emphasize that ENSO is a global phenomenon with widespread rainfall redistribution, and its impacts extend to regions like Australia, South America, and the Sahel, not just the United States.

What are the expected regional weather patterns

Amaya outlines typical regional expectations: wetter-than-normal conditions in the American Southwest during boreal winter, and drier conditions in the Pacific Northwest. The potential for a broader impact across the U.S. includes possible wetter spells in parts of the Northeast like New York during certain ENSO conditions. The overall framing is that El Niño alters the jet stream and storm paths, producing predictable shifts in some regions while unpredictable variability remains due to random atmospheric noise.

Global and ecological implications

The episode stresses El Niño as a global climate phenomenon, not limited to the U.S. It affects rainfall patterns in Australia, South America, and the Sahel, and it can influence ocean conditions globally. The discussion also delves into ecological consequences, including marine heat waves along the West Coast. A current marine heat wave presents risks to marine ecosystems and fisheries. The potential for coral bleaching is discussed, particularly if heat anomalies persist in sensitive coral regions such as Florida Keys and other warm-water habitats. Amaya notes that corals are highly susceptible to prolonged elevated temperatures, and the likelihood of bleaching increases with sustained marine heat.

Ocean heat waves, ecology and tipping points

Amaya clarifies the distinction between atmospheric heat waves and ocean heat waves. Ocean heat waves can last for months, seasons, or even years and can have lasting ecological impacts. He discusses how warmer oceans influence species distribution, with mobile species able to relocate while bottom-dwelling organisms like corals and demersal fish face higher risk. The conversation touches on the concept of ecological tipping points. While El Niño itself is unlikely to single-handedly trigger irreversible tipping points, a very strong event could contribute a substantial shock to climate systems and push some components closer to tipping-points in combination with other stressors.

Human impacts and public understanding

The hosts stress the importance of understanding this as a climate signal rather than a cyclone or hurricane. Chris Farley’s comedic reference to El Niño as a tropical storm is invoked to illustrate the public confusion around the concept. The interview emphasizes the need for careful communication about what El Niño is and what it means for everyday life, as well as the importance of interpreting warnings and model projections within the context of long-term climate dynamics rather than short-term weather events.

Model firming and what lies ahead

The episode concludes with a recap of model confidence and the timing of official declarations. The models indicate a high likelihood of El Niño, but precise strength and duration require more data and model convergence over the coming one to two months. An official declaration of arrival is not tied to a specific calendar date but is expected in the fall, once the transition into the ENSO mode is more clearly defined by both oceanic and atmospheric signals.

Conclusion

Dr. Amaya’s closing remarks underscore that while strong El Niño events can bring drought relief to drought-prone regions, they may simultaneously exacerbate marine heat waves and stress dependent ecosystems. The discussion highlights the complex, interconnected nature of climate systems and the importance of continued research and monitoring to understand and adapt to these large-scale natural climate variations as climate change continues to alter baseline conditions. The episode provides a nuanced view of El Niño as a dynamic, global climate phenomenon with significant implications for weather, oceans, and ecosystems around the world.