by Daniel Brouse
The neutral phase of the El Niño-Southern Oscillation (ENSO) occurs when water temperature anomalies in the eastern and central Pacific range between 0.5 °C and -0.5 °C. During this period, neither La Niña nor El Niño conditions dominate, and it is sometimes humorously referred to as “La Nada”; however, ENSO-neutral is anything but neutral nor normal.
ENSO-neutral refers to a phase in the El Niño-Southern Oscillation (ENSO) cycle when neither El Niño nor La Niña conditions are present in the tropical Pacific Ocean. Climate change can influence ENSO-neutral conditions in several ways:
- Increased Frequency and Intensity of Extremes: Climate change can lead to more frequent and intense weather extremes, such as heatwaves, droughts, and heavy rainfall events, even during ENSO-neutral periods. These extremes can occur independently of El Niño or La Niña events and may be exacerbated by rising global temperatures.
- Shifts in Atmospheric Circulation Patterns: Climate change can alter atmospheric circulation patterns globally, affecting the behavior of the jet stream and other large-scale wind patterns. These changes can influence the onset, strength, and duration of ENSO-neutral conditions and may lead to shifts in regional weather patterns.
- Sea Surface Temperature Anomalies: While ENSO-neutral conditions are characterized by near-average sea surface temperatures (SSTs) in the tropical Pacific, climate change can contribute to overall warming of ocean waters. This background warming may influence the baseline SSTs during ENSO-neutral periods and can potentially impact weather patterns and ocean circulation.
- Teleconnections: Climate change can modify teleconnections, which are large-scale atmospheric linkages that connect distant regions of the globe. These teleconnections play a significant role in shaping weather and climate patterns during ENSO-neutral periods. Changes in teleconnections may alter the impacts of ENSO-neutral conditions on weather and climate variability in different regions.
Overall, while ENSO-neutral conditions may not directly result from climate change, the broader changes occurring in the climate system can influence the characteristics and impacts of these neutral periods. Understanding these interactions is essential for improving our ability to predict and adapt to future climate variability and extremes.
Atmosphere-Soil-Ocean Coupling:
- Teleconnections:
- Chaos theory recognizes the concept of teleconnections, where seemingly unrelated events in one part of the Earth system influence conditions in another. For instance, changes in sea surface temperatures (linked to ocean dynamics) can affect atmospheric circulation patterns, leading to variations in precipitation and temperature on land.
- Climate Variability:
- The complex interactions between soil, atmosphere, and oceans contribute to climate variability. Chaos theory helps to understand the sensitivity of the climate system to initial conditions and how small perturbations in one component can lead to significant and sometimes unpredictable outcomes.
In 2023, the world experienced an El Niño phase, which typically reduces hurricane activity. However, the climate pattern shifted towards La Niña in 2024. La Niña patterns often amplify the Atlantic hurricane season, particularly concerning when paired with months-long streaks of record warmth across the Atlantic Ocean.
* Our climate model employs chaos theory to comprehensively consider human impacts and projects a potential global average temperature increase of 9 degrees Celsius above pre-industrial levels.
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