Research out of the University of Hawaii forecasts more frequent and extreme El Niño events, and that could mean more unpredictable rainfall, hurricane activity, sea-surface temperatures and changes in sea levels around Hawaii.
A study recently published by a team of international climate researchers considers the past 33 El Niño events spanning from 1901 to 2017, aiming to discover how climate change will affect the next generation of strong El Niño events.
What they found is that it already has.
“Results show that since the late 1970s, climate-change effects have shifted the El Niño onset location from the eastern Pacific to the western Pacific and caused more-frequent, extreme El Niño events,” University of Hawaii said in a press release about the research. “Continued warming over the western Pacific warm pool promises conditions that will trigger more extreme events in the future.”
The team’s research was focused on evaluating each of the 33 El Niño events to understand the onset location, its evolution and strength. Through the process, they identified four types different types of El Niño — each with specific onset and strengthening patterns.
El Niño is part of what’s known as the El Niño-Southern Oscillation (ENSO) climate pattern — it refers to the changes in water temperature in the central and eastern Pacific Ocean. It’s an oscillating warming and cooling pattern, according to the National Oceanic and Atmospheric Administration, and affects global climate patterns.
There are three players involved in the ENSO: El Niño, when the ocean is warming or there are above-average sea-surface temperatures; La Niña, when the ocean is cooling or there are below-average sea-surface temperatures; and ENSO Neutral, when sea surface temperatures are closer to average.
NOAA forecasters declared an end to the El Niño and entrance into an ENSO Neutral part of the cycle in August. However, a marine heat wave — unrelated to the ENSO pattern — is still heating up waters around Hawaii.
According to NOAA data, current ocean temperatures around Kauai are at 83.5 degrees, up slightly from the 82-degree average in October 2018. Forecasters point out the uptick in water temperature is also triggering warmer weather on land.
NOAA scientists and other researchers say this heat wave is akin to the 2014 hot spot known as “The Blob,” which triggered coral bleaching around Hawaii.
Scientists say the current marine heat wave enveloping Hawaii is already impacting the corals. According to the Coral Reef Watch gauges developed by NOAA, Hawaii is at the highest bleaching-alert level.
In their Oct. 22 report, Coral Reef Watch didn’t forecast that alert level to decrease until December.
During their research, scientists studying the El Niño events cited extreme shift in ENSO behavior starting in the 1970s — all events beginning in the eastern Pacific occurred prior to that time and all events born in the western-central Pacific have happened since that time.
Four of five identified extreme El Niño events occurred after 1970.
The study was headed up by Bin Wang, of the University of Hawaii at Manoa International Pacific Research Center, and it focused on the factors influencing these shifts — factors like increased sea-surface temperatures in the western Pacific and easterly winds in the central Pacific.
UH says with continued global warming, those factors may lead to more extreme El Niño events happening more frequently.
“Simulations with global climate models suggest that if the observed background changes continue under future anthropogenic forcing, more frequent, extreme El Niño events will induce profound socioeconomic consequences,” Wang said.
Written for The Garden Island Newspaper. Published October 24, 2019. Photo by Jessica Else.