Meteorologists are warning that 2023/24 is going to be a very snowy winter in many parts of the country—and El Niño is to blame. Scientists at the National Oceanic and Atmospheric Administration’s (NOAA) Climate Prediction Center, which is part of the National Weather Service, announced in June that the anticipated climate pattern had already arrived and warned it would be moderate to strong by early winter.
That’s now.
Before you stock up on snow shovels, here’s a brief refresher on El Niño, including how the climate crisis impacts it and why it could bring on snowfall. Visions of sledding through drifts of snow is the stuff of childhood, but extreme winter weather can take a toll on our health too.
What is El Niño?
Since this natural climate phenomenon only takes place about every two to seven years, you may not remember what it entails exactly. Or maybe you never knew. It’s formally called ENSO, which stands for El Niño–Southern Oscillation. Basically, it’s a cycle of warm (El Niño) and cool (La Niña) episodes that occur in the tropical Pacific Ocean. El Niño happens more frequently than La Niña. It’s marked by warmer-than-average sea surface temperatures near the equator, but its effects can be felt far and wide.
Weather experts consider ENSO the most dramatic climate system the Earth has. One of the things ENSO alters is trade winds. Typically, on non-ENSO years, trade winds blow west along the equator and bring warm water from South America toward Asia. El Niño weakens trade winds and pushes warm water east while La Niña makes trade winds stronger than usual and pushes warm water toward Asia.
ENSO can globally impact rain, flooding, drought, wildfires, public health, economies, marine life, availability of freshwater, agriculture, and so much more. Typically, an ENSO episode lasts about a year, though some last longer.
What is the link between the climate crisis and ENSO?
Scientists say no two El Niños or La Niñas are alike. That said, historical weather data for climate researchers to study isn’t robust. This makes it tricky to understand how climate change has already influenced these natural weather cycles in the past and will continue to in the future. The atmosphere holds far more heat-trapping greenhouse gases than it did at the start of the Industrial Revolution, and it’s reasonable to say this has already impacted ENSO cycles. In upcoming years, ENSO cycles are expected to be stronger. This could mean heavier rainfall, more drought, and record high temperatures, depending on the region. And extreme versions of El Niño and La Niña events, which currently take place about every 20 years, will likely increase in frequency to every 10 years.
Extreme weather—hot and cold—can harm our health in a wide variety of ways. Heat waves can exacerbate air pollution, which in turn can result in asthma attacks, increased vulnerability to infections, and even lung cancer, heart attacks, and stroke. Air pollution is especially dangerous for babies, children, and the elderly. Heavy rainfall, storm surges, and dry and chilly air can all increase the transmission of diseases, including malaria and the flu. Drought can impact drinking water, agriculture, and air quality too. In extreme cold, blood pressure can spike, leading to heart attacks and other cardiovascular events. And we know extreme weather disasters like hurricanes, wildfires, and superstorms are linked to depression, anxiety, trauma, and other mental health impacts.
So what does this have to do with snow?
Well, it really depends on where you live. El Niño tends to peak in December. In the United States, its influence is pretty weak in the summer but more apparent by late fall through spring. The current El Niño is forecasted to be strong through March 2024. According to NOAA, “Typically, moderate to strong El Niño conditions during the fall and winter result in wetter-than-average conditions from southern California to along the Gulf Coast and drier-than-average conditions in the Pacific Northwest and Ohio Valley. El Niño winters also bring better chances for warmer-than-average temperatures across the northern tier of the country.”
If you’re not a meteorologist, chances are this still doesn’t answer why you might want to go skiing this winter. The Climate Prediction Center explains it this way: “You can think of the jet stream as a river of air, which carries more moisture and precipitation along the southern tier of the United States during El Niño. As a result, it is not surprising to see a stripe of increased snowfall … over the southern half of the country.”
Still, there is no guarantee that families in some of the places in the country where snow has been notably absent in recent winters are suddenly going to be busting out snowshoes for the commute to school. Climate change is of course a factor in the decline of snowy winters of late. As NOAA notes, “Snow is flakey.”