The already strong El Niño phenomenon has entered unprecedented territory and intensified further.
Since it was first declared in June, natural climate cycles have been intensifying at a breakneck pace and are now stronger than ever to this day. And the bulking up isn’t over yet.
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Forecasters have been thinking for months that El Niño would become very strong or “super” by this fall. A key measure of its strength is now above that threshold and will continue to rise.
As a refresher: El Niño is characterized by warmer than average water temperatures along the equator of the Pacific Ocean. Rising water temperatures trigger corresponding changes in the atmosphere, which have a domino effect on weather patterns around the world.
An active Pacific hurricane season that brought multiple threats to Hawaii, a previously hurricane-free Atlantic hurricane season, and overwhelming wildfires in Indonesia are just some of the impacts of this extremely powerful El Niño.
The stronger El Niño is, the more likely it is to influence this type of weather pattern. However, it does not guarantee more extreme effects.
To understand the strength of El Niño, forecasters at the National Oceanic and Atmospheric Administration use an index called the Niño 3.4 Relative Ocean Niño Index (RONI) to measure how much sea surface temperatures are warmer than normal in a particular region of the Pacific Ocean.
The latest weekly RONI values reached an above-average 2.0 degrees Celsius, 3.6 degrees Fahrenheit. This is the standard for “very strong,” the highest official category set by forecasters. It was at this time that El Niño became unofficially known as “Super.”
These weekly values provided by NOAA capture a reliable snapshot of El Niño’s strength in real time, which is extremely important given how rapidly the El Niño phenomenon is spreading.
A weak La Niña (a cooler version of El Niño) was occurring around this time a year ago, and there are only a handful of other years in which the weather has turned into a strong El Niño so quickly, including the strongest on record in 1982-1983.
Still, using weekly values is a slight deviation from the norm.
NOAA’s most widely recognized strength metric is the three-month moving average RONI. The purpose of a moving average is to smooth out choppy short-term changes in the data to obtain a cleaner long-term average. This value is updated once a month.
This creates a climate record that goes back decades, but data lag means that it will take weeks for the measurements to accurately capture the current super-large El Niño situation.
This is not a normal phenomenon. In addition to being the strongest El Niño on record, today’s El Niño may end up being more powerful than any previous event.
The latest forecast released by NOAA last week gives El Niño a 75% chance of reaching its largest size since records began in 1950 by the end of the year.
This year’s El Niño is also occurring in a world that is much warmer than previous record events due to climate change. Comparing this year’s sea surface temperatures to previous record-breaking events shows how much fossil fuel pollution has rewritten the rules.
Climate change has literally changed the metrics used to monitor El Niño. This event was first captured by NOAA’s aforementioned RONI, which was first implemented in February.
While the old index calculated sea surface temperatures at face value, RONI subtracts out how much the Pacific Ocean has warmed due to climate change to arrive at the “true” strength of El Niño.
Still, this El Niño continues to clear hurdles toward record-breaking strength late this fall and early winter.
past, present and future
El Niño is predicted to reach its peak strength in winter, and is usually the time when its impact on the world’s weather is most pronounced, but El Niño has strengthened so quickly that it has already left many calling cards this summer.
This has been, and continues to be, a major factor in both the Atlantic and Pacific hurricane seasons. In the Atlantic, storm-killing wind shear increased to extreme levels and maintained it even during what was supposed to be the busiest time of the season. That led to record-long waits for the first hurricane of the season.
El Niño prevented the same type of wind shear over the exceptionally warm Pacific Ocean, resulting in an explosion of activity. So far, 16 storms, including two Category 5 hurricanes, have formed and raged across the eastern and central oceans, with Hawaii alone facing three tropical systems in less than a month.
14 of these are in the eastern Pacific Ocean, and although there are still two and a half months left in the season, the average seasonal storm total could exceed 15.
Indonesia is also battling widespread wildfires in other parts of the country, and the situation could worsen further. The country is drier than usual due to the El Niño phenomenon, leaving large amounts of dry vegetation vulnerable to fires, and limited rainfall for firefighters to quell ongoing operations.
While it’s clear that El Niño is already having a big impact, El Niño will be in full swing over the next few months, just in time to dictate winter weather across the United States.
