In the 1600s, Spanish fishermen hunting for mackerel and tuna in the cold Pacific waters off what is present-day Ecuador and Colombia noticed a surprising warming of the sea. It happened in only some years but always in the weeks near Christmas time. They named this rise in water temperature, El Niño de Navidad, literally The Little Boy of Christmas or Christ Child. Contemporary scientists have shortened the term to El Niño.
Modern scientists know that this ocean warming occurs when the trade winds that ordinarily blow east to west across the broad expanse of the Pacific weaken, stop, or even reverse. The winds normally drive warm surface water west, allowing cold water to upwell in the “equatorial cold tongue” that generally stretches in a strip along the Equator from western South America to the International Date Line. Such a warming episode has been also occurring since the spring of 2023.
The seventeenth-century Spaniards didn’t realize it at the time, but this ocean anomaly actually affects weather all around the world, like a series of dominoes falling—as does El Niño’s sister phenomenon, La Niña (literally The Little Girl).
Enter La Niña
La Niña wasn’t named till the 1980s, when climate scientists coined the term to describe the Pacific cold-water phenomenon that sometimes follows an El Niño—especially after an exceptionally strong El Niño. With La Niña, stronger-than-normal easterly trade winds blow above-normal amounts of surface water west, allowing frigid water to rise from far deeper in the ocean. This also shakes up global weather—again producing the meteorological version of dominoes falling.
An El Niño usually starts in the Northern Hemisphere’s spring and crescendos in November to February. It occurs every two to seven years through an elaborate interaction among prevailing winds, sea surface temperatures, the deep ocean, and perhaps unknown factors. It lasts nine to 12 months—and sometimes even for a year or two. When the equatorial Pacific Ocean grows unusually warm, as it does during an El Niño, rapidly rising warm air disrupts the jet stream—the fierce rivers of wind that flow several miles up at 100–275 mph in a generally eastward direction—which rejiggers patterns of high and low pressure, wet and dry, and hot and cold literally all over the world.
Influence on Hurricanes
Among its multitude of global weather effects, an El Niño can weaken hurricanes, which are what these giant windstorms are called when they form in the North Atlantic or Caribbean Sea. (When they’re in the Western Pacific, they’re called typhoons, and in the Indian Ocean area, cyclones.)
A La Niña brings with it weather variations as diverse as those wrought by an El Niño, including more frequent and severe hurricanes in the Atlantic. The annual hurricane season generally lasts from April through November, with 60% of hurricanes forming in August and September.
The National Oceanic and Atmospheric Administration (NOAA), the US agency that monitors global weather, is predicting a 70%–79% chance of a La Niña formation in late 2024 or early 2025.
This summer in 2024, according to the National Weather Service, an El Niño from the spring of 2023 (from a Northern Hemisphere point of view) is subsiding. It “has more or less shut off,” the agency reported, adding that a La Niña is likely to form this summer or fall, and influence the weather for the coming autumn and winter months. The National Oceanic and Atmospheric Administration (NOAA), the US agency that monitors global weather, is predicting a 70%–79% chance of a La Niña formation in late 2024 or early 2025.
Hurricanes Looming
Speaking of hurricanes, a study in 2022 in Nature Climate Change found that the number of these storms fell 13% from 1900–2000, decreasing by 23% after 1950. However, the intensity of hurricanes has been strengthening over the same period. Since 2000, the number of hurricanes making landfall in the US has been relatively stable even while their intensity has been rising, according to NOAA.
The warm-water-born El Niño has a paradoxical effect on hurricanes, causing them to lose force. This is due to the upper-atmosphere wind shear that El Niño produces, shredding the rising vortex required for a superstorm to develop.
Some scientists expect global warming to produce stronger and more frequent El Niños, which could actually weaken hurricanes. But other observers expect the opposite to be true—that rising surface temperatures in the Atlantic will feed burgeoning hurricanes with increased quantities of warm water vapor.
NOAA administrator Rick Spinrad said in May [of 2024], “There's an 85% chance of an above-normal [hurricane] season” this year.
As one can see, climate science can be inexact and contradictory. Predictions can be highly dependent on computer models, which depend on the variables—and the assumptions and perhaps biases—that are built into them. Nonetheless, NOAA administrator Rick Spinrad said in May, “There's an 85% chance of an above-normal [hurricane] season” this year. This assessment for 2024 was seconded by forecasters at Colorado State University, who said, “We anticipate a well-above-average probability for major hurricane landfalls along the continental United States coastline and in the Caribbean.”
Atlantic Storms and the Sahara
Adding a wild card to the hurricane prediction mix is the so-called Saharan Air Layer, a vast area of dry, hot, dusty air that wafts from Africa over the Atlantic. Some of the dust has even reached Florida. The hot dust plumes inhibit cloud and rain formation, and in 2024 there are “dust levels not seen in years across parts of the [Atlantic] basin,” according to Andrew Wulfeck of FOX Weather. Not surprisingly, he says, “Years with significant dust often experience reduced [hurricane] activity.”
The upshot, then, is that it’s anyone’s guess how strong and active this year’s hurricane season will be.
While the response to [hurricane] Katrina, especially in the New Orleans area, was widely criticized, the forecasting of the storm’s intensity and path was remarkably accurate.
Despite the uncertainty, the work of storm forecasters can be lifesaving. The infamous Hurricane Katrina of 2005 is just one example. While the response to Katrina, especially in the New Orleans area, was widely criticized, the forecasting of the storm’s intensity and path was remarkably accurate. Meteorologists predicted days in advance the catastrophic potential of the hurricane, leading to mandatory evacuations for millions of people in the US Gulf Coast region. Though the evacuation process was fraught with challenges, the accurate forecasting undoubtedly saved countless lives.
In the short term, weather prognostications can also help in the smart prepositioning of disaster relief resources. In the longer term, meteorological predictions on sea-level rise can help in developing coastal protection strategies. Rainfall extrapolations can help municipalities and states to make decisions on construction of dams and irrigation systems and can aid farmers in choosing what crops to plant. As climate predictions are aired in the media, people can be educated about where to live or how to better prepare for punishing weather.
The future of weather forecasting is promising; with advancements in computer modeling, atmospheric sensors, artificial intelligence, and understanding of atmospheric processes, forecasters are getting better at predicting extreme weather events. As weather scientists hone their technological ability to predict the path and intensity of storms, it will become ever more possible to shield human beings from their destruction.
Earth is always restless, never static. Its aqueous and atmospheric exterior is always on the move, boisterously and unpredictably flowing. But if technological trends continue, one day humankind might be able to live successfully with Earth’s complex meteorological patterns.
*Robert R. Selle is a freelance writer and editor, based in Bowie, Maryland.
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