Since May, scientists have seen sea surface temperatures in the tropical Pacific Ocean rise at unprecedented speeds. By some metrics, this El Niño is already considered the strongest on record, and we’re still weeks away from its expected peak.
At that point, which should arrive around December, sea surface temperatures in the Niño 3.4 region — a key area of the central equatorial Pacific that experts monitor for El Niño and La Niña — are predicted to be about 7.2 degrees Fahrenheit (4 degrees Celsius) above average. All that extra heat will destroy marine ecosystems, raise Pacific sea levels, raise global temperatures and change weather patterns around the world.
We are already seeing some of these impacts unfold. El Niño-driven drought in Indonesia and the Amazon is fueling devastating wildfires. Record high sea levels inundate the California coast. The Pacific Basin has churned out one powerful cyclone after another this hurricane season. And that’s just a taste of what’s likely to come.
But rather than seeing this Super El Niño alone as a driver of environmental disaster, many researchers see it as a rare scientific opportunity. This event will serve as a natural experiment, allowing scientists to observe how the ocean and atmosphere respond to exceptionally warm Pacific waters, improve their understanding of El Niño itself, and potentially make better predictions about our warming world.
“I’m both very worried and very excited about this El Niño,” Yassir Eddebbar, an assistant researcher at the University of California, San Diego’s Scripps Institution of Oceanography, told Gizmodo. “This is essentially a unique opportunity to test many hypotheses and assumptions that we have about El Niño.”
Observe a great El Niño with new tools
Eddebbar studies ocean biogeochemistry, focusing on how climate variability and ocean circulation affect oxygen levels, the exchange of carbon between the air and sea, and primary productivity in the Pacific basin. El Niño naturally manipulates several variables in the marine environment, and observing its effects can help researchers like Eddebbar learn how critical processes respond to these changes.
“In the past, we’ve mostly had satellite observations of temperature and chlorophyll and Argo sponges, which measure ocean temperature and salinity,” he said. The global Argo ocean monitoring network consists of approximately 4,000 floats that provide data to scientists worldwide. In recent years, a network of biogeochemical (BGC) Argo floats has grown significantly, and Eddebbar is looking forward to seeing what kind of data they collect during this El Niño.
“These are essentially autonomous instruments that descend all the way over 2,000 meters [6,600 feet]and they’re measuring temperature, chlorophyll—which is a pigment created by phytoplankton photosynthesis—as well as nitrate and oxygen,” Eddebbar explained. “So, for the first time during a major El Niño event, we have really good coverage of some of the ecosystem variables, the drivers of the ecosystems, and how they’re changing with this event.
Eddebbar is most interested in investigating how the subsurface ocean responds to large El Niños, particularly in terms of changes in nutrients, chlorophyll, oxygen content and phytoplankton production. These conditions are the basis for the functioning of the entire marine ecosystem – changing any one of them can trigger cascading effects that ripple through the food web.
NASA has also launched two new ocean observation missions in recent years: the Plankton, Aerosol, Cloud, Ocean Ecosystem (PACE) satellite and the Surface Water and Ocean Topography (SWOT) satellite. Data from PACE allows researchers to see how plankton communities respond to thermal and nutrient stress driven by El Niño, while SWOT data informs questions about how El Niño affects small circulation patterns such as eddies and turbulent flows.
Studying heat stress in the natural environment
The intensity of this El Niño will also provide an extraordinary opportunity to study how thermal stress affects marine ecology, which will help scientists understand the consequences of climate change. “It’s a natural experiment in how ocean warming — human-caused ocean warming — affects organisms, populations, species and entire ecosystems,” John Bruno, a marine ecologist and distinguished professor at the University of North Carolina at Chapel Hill, told Gizmodo.
Most of the time, this type of research is limited to laboratory aquariums that allow scientists to manipulate temperatures, but these artificial settings are not perfect analogs for the marine environment.
“It’s very unnatural, obviously,” Bruno said. “It’s not the whole ecosystem. Organisms don’t have the right currents. They behave strangely in laboratories. So, ideally in ecology, we always like to do experiments in nature.”
That’s what this El Niño allows researchers to do. And because El Niño produces localized patches of unusually warm ocean water—called marine heat waves—rather than warming the entire ocean uniformly, scientists can compare affected areas with others that haven’t warmed, effectively using them as controls.
“That’s the beauty of it — it’s a really nice natural experiment with a treatment and a control, and then there’s replication,” Bruno said. “We’ll have different places that are warm and different places that aren’t, so we can track how it affects the populations and the way the species interact.”
This El Niño will be particularly useful for studying how extreme thermal stress affects coral reefs. It is well understood that too much heat causes corals to expel their symbiotic algae – or zooxanthellae – which then leads to bleaching and potentially death. Observing how corals respond to the record warming of this El Niño will reveal how sensitive they are not only to these events, but also to future human-driven warming.
What’s more, El Niño could provide an opportunity to stress test reef restoration schemes and other climate resilience and adaptation strategies to protect coastal communities, fisheries and infrastructure. In an article published in the journal Proceedings of the National Academy of Sciences in September, Bruno and a dozen other scientists argue for this type of work.
“I feel like we’re not learning the lessons fast enough,” he said. “Climate change is happening in our lifetime, and we’re just too slow to figure out what really works.”
Untangling El Niño and climate change
While El Niño can serve as a window into certain aspects of a warmer world, it is not a perfect analog for human-caused climate change. The two phenomena produce vastly different patterns of warming, Zeke Hausfather, a climate scientist at the non-profit research organization Berkeley Earth, told Gizmodo.
However, El Niño could provide opportunities to study how Earth’s systems — especially the carbon cycle — respond to higher global temperatures, he said. This phenomenon ratchets up atmospheric CO2 levels, as warmer ocean waters absorb less CO2, while droughts and wildfires release stored carbon and reduce the amount plants take up from the atmosphere. Observing this Super El Niño will help scientists understand how Earth’s natural carbon sink will work as global temperatures continue to rise.
“Having more data, especially more really strong warm years, can potentially help answer some of these questions about how the biosphere will change more broadly as the world warms,” Hausfather said. However, he noted that individual years can only reveal so much.
Data collected during this event could also help scientists investigate questions about the complex relationship between El Niño and climate change. As this event unfolds against a backdrop of significantly higher baseline temperatures, will its impacts change? Is climate change leading to stronger El Niños? And how could the combination of El Niño and human-caused warming intensify weather extremes?
Lack of federal support will hinder research
The Trump administration has frozen, delayed or canceled billions of dollars in federal research grants to major agencies like the National Science Foundation. It also drastically reduced the budget and workforce of the National Oceanic and Atmospheric Administration, which plays a leading role in El Niño research.
“We didn’t cut everything, but a lot of our funding for this kind of work,” Bruno said. “I don’t have funding because I work on climate change, and the National Science Foundation doesn’t fund climate change anymore.” He said many of his colleagues reached out to the NSF to seek RAPID (Rapid Response Research) grants — which are reserved for situations where research must begin immediately due to urgency, such as the onset of El Niño — but were turned down.
Federally funded observational programs critical to El Niño research are also at risk.
“The BGC Argo [network] is a relatively new program, and we’re getting global coverage that has given us a really good view of the interior of the ocean, but the funding for that program runs out this month,” Eddebbar said. “It’s absolutely critical that we continue to fund these observation platforms well into the future, not just for El Niño, but for recovery, for the next El Niño, and for a number of other events we don’t fully understand.
Hopefully, researchers will find ways to navigate this treacherous funding landscape. Otherwise, this rare opportunity to study a globally consistent climate phenomenon – and better understand our warming world – could pass us by.