Australia’s Bureau of Meteorology (BOM) said average weekly sea-surface temperatures in the central Pacific had reached their highest level on record. The latest readings follow a separate record for daily sea-surface temperatures in the central-eastern Pacific set in September, surpassing the previous high during the strong 2015 El Niño.
Temperatures above 30°C have also been recorded for the first time in parts of the tropical Pacific. Scientists have observed record sea-surface temperature anomalies and unusually warm conditions beneath the ocean surface in the region used to monitor the phenomenon.
Scientists track the scale of the warming
El Niño is a natural climate pattern that occurs roughly every two to seven years and typically lasts about a year. It involves warmer-than-average surface waters in the central and eastern tropical Pacific and can alter weather patterns around the world.
The current event is developing against a background of long-term ocean warming caused by human-driven climate change. That additional warming makes it harder to compare the strength of today’s El Niño with previous events using sea temperatures alone.
Read also : El Niño is back: How a warming Pacific could reshape the world
Australian and US forecasters have therefore adopted the Relative Ocean El Niño Index (RONI), which accounts for background ocean warming to make historical comparisons more meaningful. Although the Bureau of Meteorology’s weekly RONI record only begins in 2008, its latest readings have exceeded levels recorded during the exceptionally strong 2015 event.
“We are currently witnessing an El Niño event that is unprecedented in the historical record,” climate scientist Zeke Hausfather of Berkeley Earth told the BBC.
Potential consequences for extreme weather
El Niño can influence rainfall, drought, heat and storm activity in different parts of the world. Its effects vary by region, and the strength of the ocean warming alone does not determine the impact on any particular country.
The current event has developed during an active hurricane season. Hurricane Polo, which reached Category 3 strength, caused flooding in Puerto San Carlos in Mexico’s Baja California Sur on September 29, according to the BBC.
Read also : Weather: WMO warns El Niño set to intensify between August and October
Forecasters expect El Niño to peak around December, but its eventual strength and regional effects will depend on how ocean and atmospheric conditions develop over the coming months. The latest temperature records indicate an unusually strong event, although they do not mean every region will experience more extreme weather.
