A researcher is most likely sitting somewhere in a NOAA office, gazing at a screen that shows a map of the Pacific with warm hues slowly moving eastward. These days, climate scientists essentially do that. They observe. And what they’ve been witnessing lately is an area of the ocean that, according to most accounts, is acting in ways that are both recognizable and a little unsettling.
On the surface, the current in question doesn’t seem particularly dramatic. From a fishing boat off the Galápagos or a beach in Lima, you wouldn’t notice it. However, beneath the waves, a sizable pool of warm water has been moving eastward along the equator due to a string of westerly wind gusts powerful enough to cause seasoned researchers to raise an eyebrow. According to NOAA, there is a 61% chance that an El Niño will form by July, and there is a 1 in 4 chance that it will fall into the “very strong” category, which is colloquially referred to as a super El Niño. Since the beginning of modern records, only three of those have occurred.
It’s difficult to ignore how the scientific community’s tone is changing. Professor Paul Roundy of the University at Albany recently increased the likelihood that this will be the strongest El Niño ever recorded from about 20% to about 50%. That’s a big leap. That’s the kind of revision that would raise eyebrows in another field. It tends to cause quiet anxiety in climate scientists.
When you describe the mechanics, they are nearly unremarkable. Warm water is typically pushed westward by trade winds, but these winds weaken or reverse. Heat that has been building up close to the Philippines and Indonesia begins to move east. The atmosphere abruptly reorganizes itself when sea surface temperatures in a crucial region of the central Pacific rise more than 2°C above average. Jet streams change. The tracks of storms bend. Monsoons falter. Off the coast of Peru, fisheries collapse. It is believed that the 1876 incident contributed to the famine that killed up to 50 million people before satellites were used to measure sea surface temperatures. Once you’ve read it, you won’t forget that footnote.
This one feels different because of the company it’s keeping. Already, the oceans are warmer than they have ever been recorded by satellites. There is more energy in the atmosphere. Therefore, Roundy is describing a system that has been given extra momentum before the race has really started when he claims that the warm water east of this year’s wind burst is roughly half a degree warmer than it was at the same point in 1997, the year that produced what may have been the strongest El Niño of the 20th century. Speaking with those who research this gives me the impression that the baseline has subtly shifted beneath them.
By summer, the fingerprints may begin to appear in the United States. The West and Midwest will see more rain. Stretches eastward from the Gulf Coast are drier. The southern storm track then gets stronger by winter, and California to the Carolinas are frequently hit hard. Roundy described 1982 and 1997 as “incredible flood years.” Typically, the northern tier is warm. One small blessing: Because stronger wind shear breaks up developing storms before they can organize, Atlantic hurricane seasons are frequently suppressed.
Nothing has been resolved here yet. The event’s wings could be clipped by a few strategically placed changes in the trade winds. That ship has essentially sailed, so it’s probably not enough to prevent it from being strong, but it is sufficient to prevent it from being historic. Small margins like these could determine the course of the next ten years. It’s not the uncertainty that’s strange to watch this play out. It’s the amount of riding that most people will never see on a patch of water.
