Science
Like water sloshing in a giant bathtub, El Niño begins an inevitable retreat
A few weeks ago, the Australian Bureau of Meteorology declared that the Pacific Ocean is no longer in an El Niño state and has returned to “neutral.” American scientists at the National Oceanic and Atmospheric Administration have been more hesitant, but they estimate that there is an 85% chance that the Pacific will enter a neutral state in the next two months and a 60% chance that a La Niña event will begin by August.
After an El Niño that was one of the three strongest in the last 40 years and that brought a wet winter to the U.S. — and California, in particular — this transition could mean a dramatic shift in weather as we enter the summer.
The progression from El Niño to La Niña, which is part of a broad system called the “El Niño Southern Oscillation,” or ENSO, is the result of conditions in the tropical Pacific. During the neutral phase, which is or soon will be in effect, the so-called trade winds rush from east to west along the equator. These winds push warm surface water with them, bathing Indonesia and New Guinea in the balmy waters of the “Pacific Warm Pool” and forcing cold water to rise from the deep ocean along the coast of South America.
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As an El Niño phase begins, these winds weaken, so that warm sea surface temperatures move east toward South America. This can cause climatic shifts across the globe: landslides in Peru, drought in Australia, fish die-offs in the eastern Pacific and more frequent atmospheric rivers in Southern California. These changing weather patterns also weaken the trade winds further, leading to more warm water off the coast of South America, which in turn weakens the winds, and so on.
So what prevents El Niño events from continuing to strengthen forever?
Well, it turns out you can think of the Pacific Ocean sort of like one enormous bathtub, and El Niño like a wave of warm water sloshing from one end of the bathtub to another. When that wave reaches the Ecuadorean coast, it bounces back, carrying the warm water back toward Asia and Oceania, which strengthens the trade winds, which push the warm water faster, until the wave reaches the other end of the “bathtub” — this is a La Niña phase, when the west Pacific is especially warm and the east Pacific especially cold — at which point the process repeats. This is the “oscillation” that gives ENSO its name, and it is why a strong La Niña event often follows a strong El Niño.
This winter’s El Niño event had sea surface temperature anomalies of 3.6 degrees (2 degrees Celsius), which qualifies it for the unofficial status of “very strong El Niño.” As is typical, the warm waters of El Niño led to high global temperatures, but because of the unprecedented effects of climate change, these temperatures were anything but typical. In December, when El Niño was at its peak, global surface temperatures were 0.45 degrees (0.25 degrees Celsius) above the next hottest December on record.
This increase may not seem so unusual given the current era of ever-climbing temperatures, but when you consider that the difference between the coldest December on record (back in 1916) and the second-hottest (in 2016) is less than 3.6 degrees, it is far more shocking — so surprising that prominent climate scientists have begun to publicly wonder whether there are elements missing from our understanding of climate change.
Fortunately, the onset of neutral ENSO conditions, followed by the likely La Niña, should begin to bring global temperatures down, at least temporarily. This will be little consolation for the U.S., as the National Weather Service predicts above-average summer temperatures for virtually the entire country. Moreover, La Niña events are associated with drier conditions across the southwestern U.S. that could persist into next winter. While this year’s generous Sierra snowpack should insulate California from the effects of a scorching summer, the state is never more than one below-average winter from a drought.
There are also potential implications for the rest of the country — La Niña has been linked to higher hail and tornado activity in the Southeast and an increase in hurricanes in the Atlantic and Gulf of Mexico. In fact, many experts are predicting a “hyperactive” hurricane season in the tropical Atlantic, with one forecast going as high as an unprecedented 33 named storms. On the flip side, however, there will probably be a slow hurricane season in the east Pacific, with little chance of a reprise of Hurricane Hilary’s passage over Southern California last August.
Of course, all of these forecasts — that La Niña tends to cause dry conditions in Southern California, that this location will get more hurricanes while that region gets more hail, and even how strong an El Niño or La Niña event can become — are based on correlations and theories that researchers have rigorously developed using data from the last half century.
But given the recent rapidity of climate change, there are no guarantees that the trends of the past will continue to hold in the future. In situations such as these, climate scientists generally look to computer models to understand how phenomena such as ENSO might shift over time.
Unfortunately, many climate models have not yet developed the ability to predict ENSO accurately — its complexity and the fact that it requires the ocean and atmosphere to shift in tandem make it particularly challenging to represent. This means that as we move into a new era of accelerating climate change, the future of ENSO remains uncertain.
Ned Kleiner is a scientist and catastrophe modeler at Verisk. He has a doctorate in atmospheric science from Harvard.
Science
What’s in a Name? For These Snails, Legal Protection
The sun had barely risen over the Pacific Ocean when a small motorboat carrying a team of Indigenous artisans and Mexican biologists dropped anchor in a rocky cove near Bahías de Huatulco.
Mauro Habacuc Avendaño Luis, one of the craftsmen, was the first to wade to shore. With an agility belying his age, he struck out over the boulders exposed by low tide. Crouching on a slippery ledge pounded by surf, he reached inside a crevice between two rocks. There, lodged among the urchins, was a snail with a knobby gray shell the size of a walnut. The sight might not dazzle tourists who travel here to see humpback whales, but for Mr. Avendaño, 85, these drab little mollusks represent a way of life.
Marine snails in the genus Plicopurpura are sacred to the Mixtec people of Pinotepa de Don Luis, a small town in southwestern Oaxaca. Men like Mr. Avendaño have been sustainably “milking” them for radiant purple dye for at least 1,500 years. The color suffuses Mixtec textiles and spiritual beliefs. Called tixinda, it symbolizes fertility and death, as well as mythic ties between lunar cycles, women and the sea.
The future of these traditions — and the fate of the snails — are uncertain. The mollusks are subject to intense poaching pressure despite federal protections intended to protect them. Fishermen break them (and the other mollusks they eat) open and sell the meat to local restaurants. Tourists who comb the beaches pluck snails off the rocks and toss them aside.
A severe earthquake in 2020 thrust formerly submerged parts of their habitat above sea level, fatally tossing other mollusks in the snail’s food web to the air, and making once inaccessible places more available to poachers.
Decades ago, dense clusters of snails the size of doorknobs were easy to find, according to Mr. Avendaño. “Full of snails,” he said, sweeping a calloused, violet-stained hand across the coves. Now, most of the snails he finds are small, just over an inch, and yield only a few milliliters of dye.
Science
Video: This Parrot Has No Beak, But Is at the Top of the Pecking Order
new video loaded: This Parrot Has No Beak, But Is at the Top of the Pecking Order
By Meg Felling and Carl Zimmer
April 20, 2026
Science
Contributor: Focus on the real causes of the shortage in hormone treatments
For months now, menopausal women across the U.S. have been unable to fill prescriptions for the estradiol patch, a long-established and safe hormone treatment. The news media has whipped up a frenzy over this scarcity, warning of a long-lasting nationwide shortage. The problem is real — but the explanations in the media coverage miss the mark. Real solutions depend on an accurate understanding of the causes.
Reporters, pharmaceutical companies and even some doctors have blamed women for causing the shortage, saying they were inspired by a “menopause moment” that has driven unprecedented demand. Such framing does a dangerous disservice to essential health advocacy.
In this narrative, there has been unprecedented demand, and it is explained in part by the Food and Drug Administration’s recent removal of the “black-box warning” from estradiol patches’ packaging. That inaccurate (and, quite frankly, terrifying) label had been required since a 2002 announcement overstated the link between certain menopause hormone treatments and breast cancer. Right-sizing and rewording the warning was long overdue. But the trouble with this narrative is that even after the black-box warning was removed, there has not been unprecedented demand.
Around 40% of menopausal women were prescribed hormone treatments in some form before the 2002 announcement. Use plummeted in its aftermath, dipping to less than 5% in 2020 and just 1.8% in 2024. According to the most recent data, the number has now settled back at the 5% mark. Unprecedented? Hardly. Modest at best.
Nor is estradiol a new or complex drug; the patch formulation has existed for decades, and generic versions are widely manufactured. There is no exotic ingredient, no rare supply chain dependency, no fluke that explains why women are suddenly being told their pharmacy is out of stock month after month.
The story is far more an indictment of the broken insurance industry: market concentration, perverse incentives and the consequences of allowing insurance companies to own the pharmacy benefit managers that effectively control drug access for the majority of users. Three companies — CVS Caremark, Express Scripts and OptumRx — manage 79% of all prescription drug claims in the United States. Those companies are wholly owned subsidiaries of three insurance behemoths: CVS Health, Cigna and UnitedHealth Group, respectively. This means that the same corporation that sells you your insurance plan also decides which drugs get covered, at what price, and whether your pharmacy can stock them. This is called vertical integration. In another era, we might have called it a cartel. The resulting problems are not unique to hormone treatments; they have affected widely used medications including blood thinners, inhalers and antibiotics. When a low-cost generic such as estradiol — a medication with no blockbuster profit margins and no patent protection — runs into friction in this system, the friction is not random. It is structural. Every decision in that chain is filtered through the same corporate profit motive. And when the drug in question is an off-patent estradiol patch that has negligible profit margins because of generic competition but requires logistical investment to keep consistently in stock? The math on “how much does this company care about ensuring access” is not complicated.
Unfortunately, there is little financial incentive to ensure smooth, consistent access. There is, however, significant financial incentive to steer patients toward branded alternatives, or simply to let supply tighten — because the companies aren’t losing much profit if sales of that product dwindle. This is not a conspiracy theory: The Federal Trade Commission noted this dynamic in a report that documented how pharmacy benefit managers’ practices inflate costs, reduce competition and harm patient access, particularly for independent pharmacies and for generic drugs.
Any claim that the estradiol patch shortage is meaningfully caused by more women now demanding hormone treatments is a distraction. It is also misogyny, pure and simple, to imply that the solution to the shortage is for women’s health advocates to dial it down and for women to temper their expectations. The scarcity of estradiol patches is the outcome of a broken system refusing to provide adequate supply.
Meanwhile, there are a few strategies to cope.
- Ask your prescriber about alternatives. Estradiol is available in multiple formulations, including gel, spray, cream, oral tablet, vaginal ring and weekly transdermal patch, which is a different product from the twice-weekly patch and may be more consistently available depending on manufacturer and region.
- Consider an online pharmacy. Many are doing a good job locating and filling these prescriptions from outside the pharmacy benefit manager system.
- Call ahead. Patch shortages are inconsistent across regions and distributors. A call to pharmacies in your area, or a broader geographic radius if you’re able, can locate stock that your regular pharmacy doesn’t have.
- Consider a compounding pharmacy. These sources can sometimes meet needs when commercially manufactured products are inaccessible. The hormones used are the same FDA-regulated bulk ingredients.
Beyond those Band-Aid solutions, more Americans need to fight for systemic change. The FTC report exists because Congress asked for it and committed to legislation that will address at least some of the problems. The FDA took action to change the labeling on estrogen in the face of citizen and medical experts’ pressure; it should do more now to demand transparency from patch manufacturers.
Most importantly, it is on all of us to call out the cracks in the current system. Instead of repeating “there’s a patch shortage” or a “surge in demand,” say that a shockingly small minority of menopausal women still even get hormonal treatments prescribed at all, and three drug companies control the vast majority of claims in this country. Those are the real problems that need real solutions.
Jennifer Weiss-Wolf, the executive director of the Birnbaum Women’s Leadership Center at New York University School of Law, is the author of the forthcoming book “When in Menopause: A User’s Manual & Citizen’s Guide.” Suzanne Gilberg, an obstetrician and gynecologist in Los Angeles, is the author of “Menopause Bootcamp.”
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