The World Meteorological Organisation (WMO) warned on Friday that El Nino will quickly develop into a strong event between July and September, fuelling the likelihood of extreme weather worldwide. The UN agency confirmed that El Nino conditions have already set in and will gain strength rapidly.
El Nino's Rapid Development and Classification
El Nino is a natural climate phenomenon that warms surface temperatures in the central and eastern equatorial Pacific Ocean, causing global shifts in winds, pressure, and rainfall patterns. It typically occurs every two to seven years and lasts nine to 12 months, oscillating with its opposite phase, La Nina. The WMO's monthly Global Seasonal Climate Update projects a rapid development into a strong El Nino event during July-September. The agency classifies El Nino as weak, moderate, strong, or very strong, meaning it is expected to reach the third-highest level.
"El Nino conditions have developed in the tropical Pacific and are forecast to strengthen rapidly over the coming months, increasing the likelihood of extreme weather events in many parts of the world," the WMO stated.
Ocean Warming and Heatwave Risks
Forecasts from leading global climate centres, using various models, indicate consistent and significant warming of ocean temperatures across the central and eastern equatorial Pacific. Seasonal-average sea-surface temperature anomalies are expected to exceed 2 degrees Celsius in key monitoring regions. The models show remarkable agreement, providing high confidence in the outlook, according to the WMO.
"El Nino is expected to continue strengthening during the Northern Hemisphere autumn, with its influence extending across many regions of the globe. Meanwhile, the equatorial Atlantic basin is expected to remain generally warmer than average," the WMO added.
The last El Nino contributed to making 2023 the second-hottest year on record and 2024 the all-time high at around 1.55 degrees Celsius above the 1850-1900 pre-industrial average. While El Nino usually peaks between November and February, the resulting temperature spike typically occurs later.
WMO Chief's Warning and Preparedness
WMO chief Celeste Saulo said, "El Nino conditions are already under way and are forecast to strengthen rapidly into a strong event. This will intensify the chances of drought and heavy rainfall and the risk of heatwaves on land and marine heatwaves in many regions." The WMO is stepping up early warning support to guide preparedness, especially in climate-sensitive sectors like agriculture and health. "Advanced seasonal forecasts and early warnings are vital to save lives and cushion the impact on our economies and our communities," Saulo added.
Temperature and Rainfall Impacts
The update predicts an overwhelming likelihood of above-average temperatures across most land areas between 60 degrees south and 60 degrees north, covering nearly all populated regions outside the polar areas. The July to September rainfall outlook is consistent with a strengthening El Nino, with above-normal rainfall forecast in parts of the southwestern United States and below-normal rainfall expected across the Indian subcontinent and much of Australia.
The WMO states there is no evidence that climate change increases the frequency or intensity of El Nino events. However, it can amplify the associated effects because a warmer ocean and atmosphere increase the availability of energy and moisture for extreme weather events such as heatwaves and heavy rainfall. During the northern hemisphere summer, warm waters associated with El Nino can fuel hurricanes in the central and eastern Pacific while hindering their development in the Atlantic Ocean.
