Recently, you may have heard about something called “El Niño.” But what exactly is El Niño and its sibling “La Niña”? Why do these terms seem to emerge from the depths of the scientific community and drop into popular vocabulary every few years? And how are they connected to extreme weather and our ocean?
What Are El Niño and La Niña?
El Niño and La Niña are part of a natural climate pattern in the tropical Pacific called the El Niño-Southern Oscillation, or ENSO. These two phases are different sides of the same coin, creating equally extreme shifts in temperature and air pressure.
El Niño occurs when surface water in the equatorial Pacific becomes warmer than average and easterly winds weaken. La Niña is the opposite: cooler-than-normal sea surface temperatures and stronger easterly winds. ENSO cycles can last up to seven years. El Niño and La Niña significantly impact weather patterns in all corners of the globe, often leading to more extreme weather, storm frequency and intensity.
A strong El Niño can cause flooding in some regions and drought, heat waves and wildfires in others. It often causes crop losses, coral bleaching and marine die-offs due to unusually warm ocean temperatures. El Niño tends to suppress Atlantic hurricane activity, though it increases the risk of heavy precipitation and harm to fisheries elsewhere. In the Northern Hemisphere, El Niño typically builds between March and June, peaks in December, and weakens by February.
La Niña, by contrast, often fuels an active Atlantic hurricane season and increases tornado frequency across the southern United States. Like El Niño, it builds in spring and peaks around December.
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Predicting ENSO
In 1923, the physicist Sir Gilbert Walker discovered the “Southern Oscillation,” or large-scale changes in sea level pressure across the tropical Pacific. However, it wasn’t until the late 1960s that the metorologist Jacob Bjerknes found that the changes in the ocean and the atmosphere were connected, and the hybrid term “ENSO” was born. In 1974, researchers at Oregon State University attempted to predict ENSO for the first time.
Modeling has greatly advanced since the early days. Today, scientists at the National Oceanic and Atmospheric Administration (NOAA) issue regular predictions about ENSO, which are now more accurate than ever.
NOAA gives a one-in-four chance that an El Niño could reach “very strong” intensity later in 2026, qualifying it as a “super El Niño.” This threshold has been crossed only a handful of times in recorded history, each triggering droughts, floods and record temperatures across multiple continents. NOAA’s data and models deliver life-saving early warning forecasts, like that of the predicted super El Niño, which allow communities to better prepare for and respond to extreme weather events.
Take Action
Every American, regardless of where they live, depends on NOAA’s scientists and professionals, whose work spans from the ocean floor to the far reaches of space. Unfortunately, NOAA is under threat. The Trump administration has proposed billions of dollars in cuts to the agency, which could weaken weather forecasting, disrupt fisheries management and stall critical ocean research, putting American lives and global scientific leadership at risk.
Ocean Conservancy is committed to working with NOAA to keep the public informed on climate and ocean science. We all benefit from a healthier ocean, and investing in research is the most effective way to restore ocean health and reduce the impact of severe weather events caused by El Niño and La Niña. Our ocean is not partisan, and protecting it requires all hands on deck and all sides of the aisle. Now, it’s more important than ever to demand that members of Congress prioritize our ocean. Add your name now.
The post Do You Know the Difference Between El Niño and La Niña? appeared first on Ocean Conservancy.
Welcome to Cádiz
When we arrived in Cádiz in April, we knew that we would be spending the next months working on an experiment about underwater soundscapes. What we did not yet know was how much of our time would be spent carrying equipment through the city, rebuilding experimental frames, solving technical problems and trying to convince various pieces of equipment not to end up at the bottom of the Atlantic.
Cádiz itself was a pretty good and beautiful place to start.
The city is located at the very tip of a narrow peninsula and is surrounded by the Atlantic on almost all sides. There are beaches almost everywhere, small streets leading through the old town, the harbour with its many boats and plenty of places where you can simply sit down and watch the sea. It did not take us long to understand why Cádiz is sometimes called La Tacita de Plata, the Silver Cup.
Our first evening was still fairly relaxed. After arriving and settling in, we went out together for a drink and explored a little bit of the city. It was a good introduction to our new home. The next morning, however, the relaxed part was over and GAME 2026 officially began for us.
Our project focuses on how underwater soundscapes may influence the colonization of hard surfaces by marine sessile organisms. To investigate this, we used standardized PVC settlement panels mounted on experimental frames and exposed them to different underwater soundscapes.
Over the course of the experiment, we monitored which organisms settle on the panels and checked whether the developing communities differ between the different acoustic conditions. The panels themselves were only 15 x 15 cm in size, but the frames, which were holding them while they were underwater, were much larger and required quite a bit of construction and preparation.
So, before we could investigate anything, however, we had to build everything.
Building the experiment
The first weeks in Cádiz were all about getting the experiment ready. Before the panels could go into the water, we had to prepare the equipment, rebuild the experimental frames and organize everything needed for the different parts of the experiment. Our setup consisted of large rectangular frames made from PVC pipes that carried the 15 x 15 cm settlement panels while they were in the water. In addition to this, we had speakers for the sound playbacks and ropes, buoys and weights that kept everything in position.
Although, there were frames left from a previous GAME project that was done in Cádiz, we decided to build new ones, which meant sourcing new material, cutting and assembling PVC pipes, preparing the panels and putting the different parts of the setup together. Some materials were bought locally, while others had to be ordered. This also resulted in one of our first small fieldwork adventures: transporting several metres of PVC pipes in a public transport bus through Cádiz was not exactly an everyday activity. We did not have a car at the time, and the large hardware store, where we bought some of the material, was quite far away, so getting everything back to Cádiz meant taking several buses while carrying long PVC pipes through crowded streets and vehicles. We bumped into things more than once, attracted a fair amount of attention and quickly realized that carrying several metres of PVC through a busy city is not as easy as it sounds. At one point, the combination of researchers, long PVC pipes and a local hardware store became what we jokingly refer to as the “Bus Hardware Store” episode.
Building the frames also taught us quite quickly that fieldwork rarely goes exactly according to plan. Some parts required a bit of improvisation and technical problem-solving, and when we reached a particularly stubborn technical issue, we even called Liam’s father in Germany for some additional advice. Although he was not directly involved in the project, his background in mechanical engineering and his experience with practical technical problems made him a useful person to call when we needed another perspective. A video call across Europe was not exactly part of the original plan, but it turned out to be a useful addition to our fieldwork toolkit.
At the same time as we worked on the set up, we were preparing the recordings of natural underwater soundscapes that would later be used for the experiment. For this, we built a deployment system consisting of a concrete-filled bucket, a wooden pole and a HydroMoth attached to the pole. The idea was simple: the heavy bucket keeps the structure stable on the seafloor, while the hydrophone records the surrounding natural soundscape above it. The practical part was considerably less simple. Several heavy loads of concrete had to be transported through Cádiz, and once the equipment reached the beach, getting the concrete-filled bucket into position was another workout altogether. We used a two-wheeled hand truck to move the heavy bucket across the beach and then into the shallow water. From there, we worked our way out by snorkeling and swimming, carrying and guiding the setup into position. The water was no more than about two metres deep, so there was no need for a boat.
The setup may have looked a little unconventional, but it was based on the plans we deleoped for recording natural soundscapes during the preparative course in March. After plenty of cutting, drilling, tying, carrying and assembling, the first major pieces of the project were finally ready. The frames were taking shape, the equipment was coming together and our first soundscape recordings were underway.
With the construction phase coming to an end, there was only one major question left: where exactly will we put everything?
When the plan changed
Finding a suitable experimental site turned out to be one of the more complicated parts of the project.
Our original plans involved a site in a nearby marina, but the situation changed when we were informed that construction work was planned close to the site. The associated noise would have interfered with the acoustic conditions required for our experiment, making the location unsuitable for our setup. We therefore had to move the experiment to a different location at relatively short notice. This meant adapting the setup and transporting the frames again. In the end, we found our new home at Puerto América, at the north-eastern tip of the city.
The change was a good example of how fieldwork can sometimes require a little flexibility. You can spend weeks discussing the experimental design, the set up and the site selection, but once you actually arrive at the water, there are always things that you could not have predicted from a map.
The new location gave us enough space for the experimental setup and allowed us to continue with the project. Hence, the frames were finally transported to Puerto América, weighted and installed.
Getting the frames into the water was actually much easier than building them in the first place. Once we had transported the frames to the harbour, we were able to get them into position and secure them relatively smoothly. The real challenge had been the preparation on beforehand: assembling the large PVC structures, attaching all the necessary components and making sure that everything was ready for deployment.
After weeks of preparation, the frames were finally in the water. The structures that we had spent so much time building on land were now ready to become the basis of our experiment.
From this point on, the focus shifted from building the experiment to monitoring what was happening around it.
Hydrophones, boats and one very expensive swim
Once the experiment was running, the HydroMoths became an important part of our regular monitoring. These small underwater recorders allowed us to record the acoustic conditions around our experimental frames and to measure the sound levels reaching the area of the experiment. This helped us to keep track of the underwater soundscape throughout the experimental period and to verify in hindcast what acoustic conditions the organisms on the settlement panels were actually exposed to.
Of course, regular monitorings also meant regularly getting the equipment in and out of the water. And this was when one of our more memorable fieldwork incidents happened. One day, Liam was alone at the harbour and had a fairly straightforward task: retrieve a HydroMoth, download the data and put it back into the water. Everything went well until the moment when the HydroMoth decided to make the last part of the procedure considerably easier for itself.
It slipped out of his hands and disappeared into the water.
We tried to retrieve it by diving down, but the visibility was extremely poor. Finding a relatively small piece of equipment underwater turned out to be much harder than expected, and despite our efforts, we could not recover it. It was certainly not part of the original plan, but fortunately, the experiment could continue. The lost HydroMoth has since become one of those fieldwork stories that is much easier to laugh about afterwards.
The regular monitorings also revealed how quickly conditions around the experimental site can change. One day, for example, we arrived at the harbour and found a boat parked remarkably close to our experimental setup, almost directly next to our buoys. Luckily, nothing was damaged and the boat did not cause any problems for the frames, but it was certainly an unexpected sight when we arrived.
Working in a harbour means that we are sharing the space with many other users, and sometimes the surroundings have a few surprises in store for us. Fortunately, most of them have been harmless so far.
From PVC panels to marine communities
The most interesting changes, however, did not happen above the water.
They happened on the settlement panels.
At the beginning of the experiment, the panels were simply pieces of PVC. We sanded their surfaces and standardized them so that they would provide suitable settlement substrates for marine sessile organisms. After deployment, there was not much to see.
Then the first organisms started to arrive.
During the first sampling events, we began to see the panels changing. Small organisms had settled on the surfaces, and the communities became increasingly diverse. Ascidians and bryozoans were among those colonizers that became particularly noticeable, together with worms, crustaceans and algae.
Suddenly, the panels that we had spent weeks preparing were becoming real pieces of habitat.
That was probably one of the most rewarding moments of the project. You knew exactly what a panel looked like before it went into the water. Then you retrieve it a few weeks later and had to figure out what has colonized it.
Some organisms were relatively easy to recognize. Others required a microscope, identification guides and considerably more patience.
Our supervisor was a huge help with this part of the project, especially when it came to identifying organisms that were less obvious at first glance. What initially looked like a small patch of something growing on a panel, could turn out to be an entirely different taxonomic group once you took a closer look.
And sometimes the organisms were simply fascinating to look at.
Despite the fauna and flora on the panels, we encountered small crustaceans, fish and other animals using the experimental structures as a habitat. One particularly photogenic shrimp even ended up on Liam’s hand during sampling.
The panels were therefore becoming more than just experimental units. They were small snapshots of the underwater world and the marine biodiversity around Cádiz.
The scientific question remained whether the different acoustic conditions influence the development of the communities. But before we could answer that, we had to document what was actually there.
And that meant sampling.
Sampling in the field
Our first sampling event made another aspect of fieldwork very clear: sometimes there is no perfect laboratory waiting for you at the harbour.
Since our experimental site was relatively far from the university facilities, we transported the equipment we needed directly to the field site by car. This included the microscope and the other equipment needed to examine, photograph and document the settlement panels.
There was no perfect laboratory waiting for us at the harbour. So, we built one.
We set up a small temporary workspace close to the experimental site and arranged everything we needed for the sampling. With the microscope, cameras, laptops, sampling equipment and the panels themselves, we quickly had our own little field laboratory ready to go.
Once everything was set up, the panels came out of the water. One by one, they were photographed, examined and assessed for the organisms that had settled on their surfaces. Some could be identified relatively easily, while others required a closer look under the microscope and a little more time.
The same basic procedure was repeated during the following sampling event, allowing us to compare how the panels had changed over time and which organisms had newly appeared or become more abundant.
Working directly at the field site also had its advantages. Instead of transporting the panels back and forth, we could examine and document them close to where the experiment was running and get an immediate impression of how the communities were developing.
Of course, the conditions were not always perfectly calm. Strong winds can make working at the harbour considerably more challenging, and this is where we really began to appreciate the Levante, the strong easterly wind that regularly affects the Cádiz area. By “appreciate”, we mean learning very quickly how much more complicated even a routine sampling day can become when the wind picks up. Even simple tasks require more coordination, especially when working with equipment and panels close to the water.
Nevertheless, the sampling days became one of the most interesting parts of the experiment so far. Every time we brought a panel out of the water, there was something new to discover.
The youngest member of the GAME team
There was also one very important member of the team who deserves a special mention.
During one of our most recent monitoring days, we had some unexpected assistance from a four-year-old.
While we were reading out the equipment, working on the frames and dealing with the usual collection of sampling tasks, our youngest helper decided that watching from the side was not enough. He wanted to participate.
So he did.
For a short time, we had officially found the youngest member of the GAME team. He may not have been able to explain the experimental design or tell us anything about sound pressure levels, but he was very enthusiastic about helping with the work. It was a small moment, but it was also a nice reminder that fieldwork is rarely as isolated as it can sound when described in a scientific paper. People around us had become part of the experience, whether they were helping with equipment, giving advice, asking questions or simply were curious about what two researchers are doing at the harbour with a collection of PVC pipes.
And occasionally, they became part of the team.
Life outside the frames
Of course, our time in Cádiz did not consist entirely of PVC, HydroMoths and sampling.
Living in Cádiz for several months also meant getting to know the city and the surrounding region outside the harbour. We spent a lot of our free time near the sea, whether that means going to the beach, playing sport or simply enjoying the city after a long day of fieldwork. With beaches, the old town and the harbour all within easy reach, there was usually no shortage of places to spend a few hours away from the experiment.
We have also used our time here to explore more of Andalusia. We visited Sevilla, where we could experience one of the region’s larger and more historic cities, and travelled to Tarifa, where we joined a whale watching trip and got to see some of the marine wildlife of the area from a completely different perspective.
