The transition from El Niño to La Niña is complicating weather patterns, alongside climate change that is intensifying storms and floods.
Master Le Thi Xuan Lan, former head of forecasting at the Southern Regional Hydro-Meteorological Center, stated that Typhoon Yagi occurred during the phase transition from ENSO (neutral) to La Niña (cooler sea temperatures) beginning in September. However, according to Ms. Lan, this phase transition is not the primary cause of the strong typhoon and the subsequent floods affecting many provinces in northern Vietnam. The main reason is the impact of climate change, which is causing La Niña to have anomalous characteristics, leading to stronger storms, frequent occurrences, heavy rainfall, severe flooding, and prolonged landslides.
Flooding after Typhoon Yagi in Yen Ninh Ward, Yen Bai City on September 9. (Photo: Ngoc Thanh).
The strong and anomalous factors of La Niña are explained by meteorological experts, due to the impact of climate change causing atmospheric warming, which many refer to as global warming. This warming atmosphere leads to an increase in sea temperatures.
According to Ms. Lan, a mere increase of 0.5 degrees Celsius in sea temperatures is sufficient to provide the energy needed for stronger storms. A warmer atmosphere also alters circulation patterns, causing air masses to operate more vigorously or erratically, resulting in extreme weather phenomena.
She believes climate change is the primary factor causing unusual weather patterns, prolonging phases of El Niño, ENSO, and La Niña, leading to increasingly complex, severe, and prolonged natural disasters such as storms, floods, droughts, severe cold, and saltwater intrusion.
Prof. Dr. Phan Van Tan, a meteorology and climate change expert at the University of Natural Sciences, Vietnam National University, Hanoi, stated that the transition from El Niño to La Niña complicates weather, which is most evident through Typhoon No. 3, Typhoon Yagi – described as the strongest typhoon in the past 30 years in the South China Sea. “The occurrence of storms during this period is not unusual, but the strength of the storm is what is unusual,” he said, adding that “climate change disrupts many regulatory aspects.”
During the late August to early September period, sea temperatures are warmer than at other times of the year, creating favorable conditions for rapid storm development. Coupled with other factors such as high sea surface temperatures, moderate storm speeds, and accumulated energy in warm waters, along with moderately favorable wind shear conditions, this leads to the rapid intensification of storms, potentially becoming super typhoons.
He further mentioned that forecasts regarding El Niño and La Niña are conducted by meteorological centers worldwide (Vietnam has yet to establish such forecasts), aiming to predict the likelihood of these phenomena occurring each month, updated monthly and serving as a basis for subsequent forecasts, extending predictions up to nine months ahead. Currently, forecasts indicate that the La Niña phase has begun and is expected to last at least until spring next year.
Statistics show that La Niña years tend to have more storms compared to El Niño years due to the convective system in the western region pushing closer to our coastal areas, resulting in not only storms but also increased rainfall. Forecasts indicate average monthly rainfall from now until the end of the year will be higher than in previous years, by at least 10-20%. Model forecasts suggest that in September, there may be at least two storms (or possibly tropical depressions or disturbances) affecting the South China Sea, predominantly impacting the Central and North Central regions.
Therefore, he advises the public to closely follow forecast information, especially weather forecasts, and monitor unusual weather events such as storms, tropical depressions, heavy rainfall, or severe cold to respond promptly.
Ms. Lan noted that forecasts for the peak storm and flood months in Vietnam from September to November indicate that 2 to 3 storms may occur in a month. Flooding may persist until early 2025, primarily affecting the North and Central regions. By the end of the year, the South Central Coast and the South may be directly impacted by at least one storm. She analyzed that due to the mountainous terrain in the North, with steep slopes, wide and extending riverbeds, and numerous hydropower lakes, the flooding situation, particularly flash floods and landslides, is very complex and significantly affects the local population.
To mitigate the damage from natural disasters, Ms. Lan reiterated the importance of forest preservation to reduce the impact of upstream flooding. “If forest areas continue to shrink, the natural disasters caused by climate change will become increasingly severe and unpredictable,” she warned.
La Niña may lead to powerful storms in the Atlantic, such as Hurricane Matthew which struck Haiti in 2016. (Photo: NASA).
La Niña and El Niño are two extremes of a recurring climate pattern that can affect weather worldwide. Experts explain that La Niña occurs when the temperature in the eastern Pacific along the western equatorial region of South America is at least half a degree Celsius cooler than normal. In contrast, during El Niño periods, this area warms. The temperature fluctuations appear minor but can significantly impact the atmosphere through a cascading effect across the planet.
Since June 2023, when El Niño began, each month has set new high temperature records. In the summer of 2023, the world witnessed record-breaking global temperatures for ten consecutive months. La Niña may help temper temperatures, but greenhouse gas emissions leading to global warming are still on the rise. While the transition between El Niño and La Niña can cause short-term temperature fluctuations, the overall trend is that the Earth is getting hotter.
According to Live Science, due to the impending impact of La Niña and the currently extremely warm surface temperatures in the Atlantic, a research team on climate and tropical weather at the University of Colorado predicts a very active Atlantic hurricane season, estimating 23 named storms (above the average of 14.4) and 5 Category 3 storms or higher. This year could resemble 2010 and 2020, both of which had active hurricane seasons, although it remains uncertain if the intense storms will impact land.
