Climate models converge on a familiar disruption—with new uncertainties

A subtle but consequential shift is unfolding across the tropical Pacific. After months of relative calm, ocean surface temperatures are climbing again—an early signal that El Niño may return by mid-2026, according to the World Meteorological Organization.

The agency’s latest seasonal outlook suggests that the climate system is moving decisively away from neutral conditions. By the May–July window, models indicate a strong likelihood of El Niño forming, with further intensification possible as the year progresses.

“Climate models are now strongly aligned,” says Wilfran Moufouma Okia, pointing to growing confidence in forecasts that, just months ago, remained uncertain.

The quiet power of ENSO

At the centre of this shift lies the El Niño–Southern Oscillation (ENSO)—a vast, coupled ocean-atmosphere system that acts as one of Earth’s most powerful climate regulators. Its warm phase, El Niño, is defined by elevated sea-surface temperatures in the central and eastern equatorial Pacific.

Though cyclical, ENSO is far from predictable. Events typically emerge every two to seven years, lasting up to a year. Yet each iteration differs in intensity, spatial structure and downstream effects.

This variability is precisely what makes ENSO both scientifically fascinating and societally critical.

El Niño: A world tilted toward warmth

If El Niño does take hold, it will arrive in a climate system already primed for heat. The WMO projects a near-global prevalence of above-average land temperatures in the coming season, with especially strong signals across parts of North America, Europe and northern Africa.

El Niño tends to nudge global temperatures upward by releasing heat stored in the Pacific Ocean into the atmosphere. When layered onto long-term warming driven by greenhouse gases, the effect can be pronounced—as seen in 2024, which set new global temperature records.

Still, scientists are careful not to overstate the connection. Climate change has not been shown to increase the frequency of El Niño events. What it does appear to do is amplify their consequences—intensifying rainfall extremes, droughts and heatwaves in a warmer, more moisture-laden atmosphere.

Rainfall rearranged

El Niño’s influence extends well beyond temperature. It reorganises atmospheric circulation, shifting rainfall belts and storm tracks across continents.

Historically, El Niño years bring:

• Wetter conditions in parts of South America, East Africa and the southern United States
• Drier conditions across Australia, Indonesia and sections of South Asia

At the same time, the Pacific hurricane season often becomes more active, while the Atlantic basin tends to quieten.

Yet these are tendencies, not guarantees. Each event unfolds with its own geographical signature.

The forecasting challenge

Despite improving models, predicting ENSO remains notoriously difficult—particularly during the Northern Hemisphere spring. This period, known as the “spring predictability barrier,” is when forecasts are most prone to error.

“It is a transitional time for the climate system,” Okia explains. “Confidence improves after April, as the signal becomes clearer.”

For now, projections suggest that the developing El Niño could be moderate to strong, though the full trajectory will only become apparent in the months ahead.

Why it matters now

For policymakers, farmers and disaster planners, the implications are immediate. ENSO forecasts inform decisions on crop cycles, water storage, and emergency preparedness months in advance.

But there is a broader scientific significance, too. Each El Niño event offers a natural experiment—an opportunity to observe how a warming world responds to one of its most powerful internal oscillations.

If 2026 does usher in another El Niño, it will not simply be a repeat of past events. It will be a test of how climate variability and climate change now interact in real time.

And increasingly, those two forces are no longer easy to separate.

From nutrient-rich to energy-dense but less nourishing—climate change is transforming the composition of ocean food at its source.

Climate change could fundamentally alter the nutritional foundation of the ocean, with new research suggesting that warming waters may turn phytoplankton—the base of the marine food web—into a form of “fast food” with reduced nutritional value.

A study by researchers at the Massachusetts Institute of Technology (MIT), published in Nature Climate Change, finds that rising ocean temperatures could shift phytoplankton composition from protein-rich to carbohydrate-heavy, particularly in polar regions. This transformation could have cascading effects across marine ecosystems and ultimately impact human food systems.

A Shift at the Base of the Food Chain

Phytoplankton are microscopic, plant-like organisms that form the primary food source for a wide range of marine life, including krill, small fish, and jellyfish. These organisms, in turn, sustain larger species and top predators, including humans.

The study suggests that under continued greenhouse gas emissions through 2100, ocean warming will significantly alter the nutritional profile of these organisms. According to the researchers’ model, phytoplankton in polar regions could shift their balance of proteins to carbohydrates and lipids by approximately 20 percent.

“We’re moving in the poles toward a sort of fast-food ocean,” said lead author Shlomit Sharoni, an MIT postdoctoral researcher, in a media statement. “Based on this prediction, the nutritional composition of the surface ocean will look very different by the end of the century.”

Why Nutritional Composition Matters

While previous research has largely focused on how climate change affects phytoplankton populations, this study highlights a less explored dimension: their internal composition.

“There’s been an awareness that the nutritional value of phytoplankton can shift with climate change,” Sharoni said in a media statement, “But there has been very little work in directly addressing that question.”

Phytoplankton are composed of essential macromolecules such as proteins, carbohydrates, and lipids. These components determine their nutritional value for the organisms that consume them. Any imbalance at this foundational level can ripple through the entire food chain.

“Nearly all the material in a living organism is in these broad molecular forms, each having a particular physiological function, depending on the circumstances that the organism finds itself in,” said Mick Follows, professor at MIT.

Warming Oceans, Changing Chemistry

Using a combination of laboratory data and advanced ocean models, the researchers simulated how phytoplankton respond to changing environmental conditions such as temperature, light, and nutrient availability.

Under current conditions, phytoplankton cells are composed of slightly more than 50 percent protein. However, in future climate scenarios where global temperatures rise by around 3°C, this balance shifts significantly.

In polar regions, reduced sea ice allows more sunlight to penetrate the ocean surface, decreasing the need for light-harvesting proteins. At the same time, warmer temperatures and reduced ocean circulation limit the availability of nutrients such as nitrogen and iron.

As a result, protein levels in phytoplankton could decline by up to 30 percent, while carbohydrates and lipids increase.

Uneven Global Impacts

The effects of this shift are not uniform across the globe.

While phytoplankton populations in polar regions may increase, their nutritional quality is expected to decline. In contrast, subtropical regions could see a reduction in phytoplankton populations by up to 50 percent due to reduced nutrient availability.

In these regions, phytoplankton may adapt by moving to deeper waters, where they can access both light and nutrients, potentially increasing their protein content slightly.

Overall, however, the global trend points toward a more carbohydrate-heavy and less nutrient-dense ocean ecosystem.

Early Signs Already Visible

The researchers compared their model with real-world observations from Arctic and Antarctic regions. The findings indicate that this shift is already underway.

“In these regions, you can already see climate change, because sea ice is already melting,” Sharoni said in a statement. “And our model shows that proteins in polar plankton have been declining, while carbs and lipids are increasing.”

Follows added that the implications extend beyond marine ecosystems.

“It turns out that climate change is accelerated in the Arctic, and we have data showing that the composition of phytoplankton has already responded,” he said in a media statement. “The main message is: The caloric content at the base of the marine food web is already changing. And it’s not a clear story as to how this change will transmit through the food web.”

Implications for Marine Life and Humans

The long-term consequences of this shift remain uncertain. Some species may struggle with reduced protein availability, while others that rely on lipid storage could adapt more easily.

However, scientists warn that any disruption at the base of the marine food chain could have far-reaching impacts on biodiversity, fisheries, and global food security.

As the study highlights, climate change is not only altering how much food the ocean produces—but also how nutritious that food is.

New research suggests climate warming may modestly enhance the atmosphere’s ability to break down methane, though competing chemical processes add uncertainty.

A new study by researchers at the Massachusetts Institute of Technology (MIT) finds that rising global temperatures could slightly increase the atmosphere’s ability to break down methane, one of the most potent greenhouse gases.

Methane is a major driver of global warming, second only to carbon dioxide. However, it does not persist as long in the atmosphere due to the presence of hydroxyl radicals—highly reactive molecules often described as the “atmosphere’s detergent” for their role in breaking down pollutants.

Balancing Effects of Water Vapour and Natural Emissions

The MIT team developed a new atmospheric model to understand how hydroxyl radical (OH) levels may respond to warming temperatures. Their findings reveal a complex balance of competing effects.

As global temperatures rise, atmospheric water vapour is expected to increase, boosting OH levels by about 9%. However, higher temperatures will also lead to increased emissions of natural gases from plants—known as biogenic volatile organic compounds—which can reduce OH levels by approximately 6%.

The net effect, according to the study, is a modest increase of around 3% in the atmosphere’s capacity to break down methane under a 2°C warming scenario.

Why Hydroxyl Radicals Matter

Hydroxyl radicals play a critical role in regulating atmospheric chemistry. They react with methane and other gases, breaking them down into less harmful compounds.

“About 90 percent of the methane that’s removed from the atmosphere is due to the reaction with OH,” said study author Qindan Zhu in a statement.

Beyond methane, OH also helps remove air pollutants and gases that affect public health, including ozone.

“There’s a whole range of environmental reasons why we want to understand what’s going on with this molecule,” said Arlene Fiore, a professor at MIT.

New Model Offers Deeper Insights

To conduct the study, researchers developed a model called “AquaChem,” which simulates atmospheric chemistry under different climate scenarios. The model builds on simplified “aquaplanet” systems, allowing scientists to isolate atmospheric processes without the complexity of land and ice interactions.

Using this model, the team compared current climate conditions with a scenario in which global temperatures rise by 2°C—widely considered a likely outcome without significant emissions reductions.

Uncertainty Around Natural Emissions

Despite the findings, researchers caution that there is still significant uncertainty—particularly regarding how plant emissions will respond to climate change.

Biogenic emissions, such as isoprene released by trees, appear to play a major role in influencing OH levels but remain difficult to predict accurately.

Future research will aim to refine these estimates and better understand how different climate scenarios could affect atmospheric chemistry.

Implications for Climate Projections

Even small changes in hydroxyl radical levels can have significant implications for how methane accumulates in the atmosphere.

“Understanding future trends of OH will allow us to determine future trends of methane,” Zhu said.

As methane continues to rise alongside carbon dioxide, insights into these chemical processes will be critical for improving climate models and informing mitigation strategies.