Climate Matters: Scientists revise El Niño measurement due to global warming
Global temperatures have taken an unexpected sharp climb in recent years, prompting scientists to reconsider how some atmospheric patterns are calculated.
NOAA announced earlier this month that it will shift to a new index to calculate the El Niño Southern Oscillation (ENSO), a long-term climate pattern that influences weather in North America and around the globe.
According to the agency, "The Climate Prediction Center is making the shift to use the Relative Oceanic Niño Index (RONI) to better designate past events and predict future ENSO. The traditional Oceanic Niño Index (ONI) relies on a departure from 30-year average that struggles to keep pace with anomalous changes in tropical sea surface temperature (SST), which is particularly problematic in real-time when using a time lagged climatology. RONI solves this problem by comparing the ENSO region to the global tropics, thereby reducing the dependency on the climate base period," NOAA says.
In simpler terms, El Niño and La Niña have historically been calculated using long-term averages from the past 30 years, which are struggling to keep pace with climate change today.
Under a new system, known as the Relative Oceanic Niño Index, ocean temperatures in the eastern Pacific will be compared with the entire tropics to provide a more accurate picture of how abnormally warm the region is.
Scientists have long known that ocean temperatures in the eastern Pacific fluctuate on an irregular 2 to 7-year basis, between a "cool" La Niña phase and a "warm" El Niño phase. South American fishermen have been aware of the phenomenon for centuries, as they noticed the appearance of warm ocean currents in the eastern Pacific around Christmastime. They called it El Niño de Navidad, or "the boy child", in reference to the baby Jesus.
El Niño and La Niña both influence global weather patterns by shifting regions of rising and sinking air thousands of miles away, affecting temperature and precipitation trends in many parts of the world, including the U.S.
However, here in the central part of North America, the influence of El Niño and La Niña can be pretty hazy.
"For Missouri, we're kind of stuck in the middle, and that doesn't really influence Missouri one way or another," says Mark Britt, a meteorologist with the National Weather Service in St. Louis.
While the fingerprints of El Niño and La Niña can be seen in other parts of the country, Mark says our position in the middle gives us a mix of everything. "It's cooler to the north and drier and warmer to the south," Mark explains, "Missouri is just not influenced particularly one way or another."
The new system of measuring El Niño and La Niña doesn't change their effects on our weather, but it may provide a more accurate forecast ahead of these events. When local meteorologists are more informed about upcoming climate trends, it can increase accuracy in forecasts, both big and small.
