Volatile Climate Splits Weather Agencies on El Niño Messaging

(Bloomberg) — Predicting the onset and intensity of the weather-roiling El Niño and La Niña events is crucial for global markets, and meteorologists need to get the messaging right or risk sparking confusion and backlash.

Australia’s forecaster, which faced criticism last year after an unusual El Niño, is taking a less-is-more approach, while the World Meteorological Organization and the Philippines are fielding requests for more detailed and frequent information. The contrasting styles underscore the challenge for agencies seeking to balance demands for certainty against the volatility of weather. 

An accurate read on the status of the El Niño-Southern Oscillation is essential for governments, energy markets and farmers planning their cropping regimes, especially as global warming exacerbates extreme weather. Warm and cold phases can cause sapping droughts or unleash drenching rain from the Asia-Pacific to the US, and cost the global economy trillions.

“It’s vital information,” said Tristan Meyers, a meteorologist at New Zealand’s National Institute of Water and Atmospheric Research. “It gives you a little bit of an insight into how the seasons will develop.”

South American fishermen first noticed periods of unusually warm water in the Pacific Ocean centuries ago, which they named El Niño de Navidad, and modern researchers came to realize its importance to global weather in the 1960s. La Niña was named about two decades later and today, climate variations are monitored by an array of buoys across the Pacific.

Australia’s weather bureau stopped issuing its fortnightly updates in December because they had “created an overemphasis on ENSO as a predictor of seasonal conditions” and “the likelihood and severity of weather events,” according to a spokesperson. The agency says its long-term forecasts on rain and temperatures are a better guide. 

“El Niños and La Niñas just weight the probability of having wetter or drier, or warmer or cooler conditions in different parts of the world, but they don’t rule out the possibility of the opposite,” said Andrew King, an associate professor in climate science at the University of Melbourne.

That subtlety can often be lost in communication, as the Australia bureau found after its declaration of El Niño in late 2023. Despite the call being correct, the agency faced intense criticism after an atypical event: wet instead of dry.

“When the forecasts end up being so wrong, that has a huge effect on us,” said Rhys Turton, a crop farmer in Western Australia and the chair of industry group GrainGrowers Ltd. “You can’t reverse those decisions you made early in the season, like what to plant, or how much to plant.”

People want certainty from a discipline that can’t deliver it, according to Jon Gottschalck, chief of the US Climate Prediction Center’s Operational Prediction Branch. Forecasts are based on probabilities and sometimes the unexpected or low-odds outcome happens, which can lead to complaints.

“Nuances in our forecasts mean something even if stakeholders don’t like to see it,” said Gottschalck, adding that “ENSO is still the most predictable seasonal and inter-annual prediction we have.”

ENSO is monitored using indexes that measure deviations in Pacific Ocean temperatures from averages in preceding decades, and with the world getting hotter, there are concerns about overestimating El Niños and underestimating La Niñas. Some are using methods to remove the background noise caused by global warming, but more research is needed on their effectiveness.  

The US agency, for example, informally tracks a relative oceanic Niño index that subtracts the tropics-wide sea temperature anomaly. The relative measure has consistently run cooler than the traditional index over the past year by at least 0.5C (0.9F) — the very threshold that makes or breaks El Niño or La Niña events.

Even without the challenge of a warming world, global ENSO forecasting can still create uncertainty, with this year’s yes-no La Niña an example of that conundrum. Earlier this year, the Philippines and the US said La Niña had developed, while Japan and Australia still see conditions as neutral. The lack of unity stems from each nation using different standards for measuring ENSO thresholds.

“It’s like a philharmonic concert without a conductor. Each instrument, whether it’s the Australian one or the American one, or the French one, they play their best score perfectly, but it doesn’t prevent a cacophony occasionally,” said Alexandre Peltier, a meteorologist and the head of the climatology division at Météo-France in New Caledonia.

The WMO, a United Nations agency that already issues ENSO outlooks by drawing on forecasts from several dozen meteorological centers worldwide, is creating a new “one-stop repository” to provide more detailed and frequent information. The hub is in response to growing demand from member states following “the rapid evolution of ENSO events in recent years,” said Wilfran Moufouma Okia, chief of climate prediction services at the agency.

In the Philippines, the country’s weather agency is seeking to provide more detailed information that’s tailored to specific regions and industries, including advice on what to do before, during, and after an El Niño or La Niña. The nation is on the frontline for typhoons that originate in the western Pacific.

As for Australia, its bureau will still make a declaration if there’s any change in ENSO status, though its less-is-more approach may still cause issues. University of Melbourne’s King said it risks leaving a vacuum to be filled by less credible sources that some may even mis-attribute to the weather agency. 

“The bureau ends up with a worse outcome, potentially,” he said.

–With assistance from Keira Wright and Kevin Dharmawan.

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