An anticipated transition to La Niña conditions in the Pacific Ocean has faced another delay. Current forecasts indicate that only a weak La Niña event may materialize by the end of November, limiting its potential cooling effect on global average temperatures.
“The reasons behind this delay remain unclear,” stated a NOAA representative. “If the cause were known, predictions could have been more accurate.”
La Niña represents the cool phase of the El Niño Southern Oscillation (ENSO), a significant climatic cycle impacting global weather patterns. This phenomenon experiences periods of La Niña, neutral temperatures, and warm El Niño phases over the years.
A rare “triple-dip” La Niña occurred from 2020 to 2022, transitioning to a strong El Niño in 2023. This warming event, combined with greenhouse gas emissions, has contributed to the record-breaking global temperatures experienced this year.
After the decline of El Niño and the emergence of neutral temperatures in May, forecasters had expected a swift return to La Niña conditions. In June, NOAA researchers projected a greater than 60 percent chance of La Niña developing between July and September, which later rose to over 70 percent for the period between August and October. This led to expectations of a tumultuous Atlantic hurricane season.
While sea surface temperatures in the Pacific have cooled since then, a full-blown La Niña has yet to emerge, possibly leading to a notable slowdown in hurricane activity this season. NOAA now estimates a 60 percent chance of La Niña conditions developing by the end of November, predicting a brief and weak event to last from January to March.
The discrepancy between initial forecasts and current projections is not unexpected, as early-year projections often lack accuracy due to the sensitivity of wind and water conditions. Historically, four La Niña events have developed late in the year since 1950.
The reasons for this delay are still being investigated. Observations indicate that trade winds have been sluggish in parts of the eastern Pacific, potentially maintaining warmer equatorial waters than anticipated; however, this could be more of a symptom than the primary cause.
The impact of anthropogenic climate change on the delayed arrival of La Niña remains under scrutiny. Some studies suggest climate change may increase the variability of ENSO, but this topic continues to spark debate within the scientific community.
Despite ongoing delays, a weak La Niña is gradually forming, likely exerting its characteristic influence on global weather patterns, such as drier conditions in the southern U.S. and increased rainfall in Indonesia. However, being a weak event, its potential to lower global average temperatures significantly remains minimal. “While we may witness a slight dip in global averages, temperatures are still considerably elevated,” noted a climate expert.
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