Can Whitening Clouds Mitigate a "Super El Niño"? New Questions Arise from Climate Manipulation Technologies

The Earth's climate sometimes sends ripples across the globe from changes in a single ocean region. El Niño, characterized by rising sea surface temperatures in the equatorial Pacific, is a prime example. Changes occurring in tropical seas can affect distant regions, manifesting as heavy rains in South America, droughts in Southeast Asia and Australia, global high temperatures, fluctuations in agricultural prices, increased infection risks, and impacts on fisheries.

In 2026, global meteorological agencies are increasingly vigilant about the development of a strong El Niño. Amidst this, a research team from UC San Diego's Scripps Institution of Oceanography has posed a rather probing question: If a strong El Niño is almost certain to cause significant damage, should humanity consider temporarily intervening in the climate to weaken its impact?

At the heart of the research is a geoengineering technology known as "marine cloud brightening." The concept appears simple: add fine sea salt particles to low clouds over the ocean to make them whiter and more reflective. This would bounce some of the sunlight back into space, reducing the energy reaching the sea surface. If the ocean cools slightly, the exchange of heat with the atmosphere might change, potentially suppressing the development of El Niño.

However, this is not merely a "heat mitigation" strategy. El Niño is linked to global atmospheric circulation. Brightening clouds in one area could affect rain, wind, and temperatures elsewhere. The problem is that both the effects and side effects could be global.

The reason this research has garnered attention is that, despite not conducting an actual large-scale experiment, there was a real-world "clue." The "Black Summer" bushfires in Australia from 2019 to 2020 released vast amounts of smoke and aerosols into the atmosphere. These particles are believed to have interacted with clouds, brightening them over the southeastern Pacific.

This phenomenon was regarded as a "natural experiment" where nature produced effects similar to artificial marine cloud brightening. Previous studies suggested that changes in clouds due to this smoke might have strengthened La Niña-like climate patterns formed in 2020. La Niña, the opposite of El Niño, is characterized by cooler sea surface temperatures in the equatorial Pacific. In other words, the smoke from the fires may have brightened clouds, altered the solar energy reaching the sea surface, and consequently promoted climate changes opposite to El Niño.

Based on this "natural experiment," the research team used models to examine what might have happened if similar cloud brightening had been intentionally induced during past major El Niño periods. The study included large El Niños that began in 1997 and 2015. Simulation results suggested that early-stage marine cloud brightening in specific ocean regions could potentially mitigate the impact of El Niño to some extent. When implemented over the central Pacific, it could also enhance cooling and drying effects related to La Niña by over 40%.

What is crucial here is that the researchers are not advocating for immediate implementation. Rather, they are suggesting there is room for consideration from a different angle than traditional geoengineering discussions.

Previously, solar reflection-type geoengineering was often discussed as a long-term means to curb global warming itself. Proposals like injecting aerosols into the stratosphere or blocking sunlight in space are emblematic of this. However, long-term climate intervention comes with challenges like permanent management, international cooperation, the risk of rapid warming upon cessation, and political conflicts.

In contrast, the current proposal is slightly different. Instead of cooling the entire Earth over the long term, it suggests intervening for a short period and in a limited area during the peak of naturally occurring El Niño. Researchers believe this could help reduce the damage from floods, heatwaves, and droughts while minimizing social and technical risks compared to long-term deployment.

Indeed, the economic losses from El Niño are enormous. Analyses suggest that past major El Niños left impacts on the global economy not only during the occurrence year but for several years afterward. The damage tends to linger longer in tropical regions and low-income countries, and when agriculture, water resources, infrastructure, and health damages overlap, it becomes more than just a weather event. If the damage could reach trillions of dollars, there is some persuasive argument for researching options to slightly adjust the climate itself, in addition to flood control, agricultural support, and early warning systems.

However, when this topic is received on social media, reactions quickly polarize. While the observable reactions are not yet a major wave, the Phys.org article itself had few shares and comments shortly after publication. On the other hand, related social media posts and article introductions highlight three main reactions.

The first reaction emphasizes caution over expectation. While some voices advocate for research if abnormal weather can be suppressed, there is strong anxiety about the dangers of tampering with the climate itself and who would bear the side effects. Particularly, if rainfall patterns change, the issue of which countries benefit and which suffer losses appears intuitively unfair to many.

The second reaction is a reflexive distrust of the term geoengineering. On social media, the topic of climate intervention easily gets linked to conspiratorial contexts. In fact, comments on related El Niño posts include skeptical voices questioning, "Is this geoengineering?" and reactions that oversimplify weather phenomena as human manipulation. Scientifically, this research is a model study, and there are no plans for actual large-scale intervention at present. However, from a general perception, the distance between "research" and "implementation" can easily become blurred.

The third reaction is a cautious evaluation from experts. In scientific media and climate policy communications, the tone often views this research as "interesting but with significant barriers to implementation." Compared to stratospheric aerosol injection, marine cloud brightening might be usable regionally. However, being regional does not necessarily mean it is safe. On the contrary, altering clouds or sea surface temperatures in specific regions could affect rainfall and monsoons in other areas. Climate is not bounded by national borders.

The WIRED article acknowledges the scientific validity of the research while also introducing experts' concerns that it could become a "political nightmare" if implemented. Models are not perfect, and unforeseen problems could arise. If one country leads the intervention and another experiences droughts or floods afterward, it could become a political issue even if the causal relationship is unclear. Climate intervention is as much an issue of international order as it is of science and technology.

The essence of this research is not a simple proposal to "implement geoengineering." Rather, it reflects the reality that as the climate crisis progresses, humanity will be forced to discuss options previously avoided. If greenhouse gas emissions are not reduced and the global average temperature continues to rise, the damage from natural variations like El Niño will become even greater. This could lead to debates about whether dangerous technologies are better than doing nothing.

However, there is also a pitfall. Advancing geoengineering research could potentially weaken the pressure to reduce fossil fuel consumption. If the idea that "we can just whiten the sky if necessary" spreads, reducing greenhouse gas emissions, the root cause, might be postponed. This represents a significant moral hazard in climate policy.

Moreover, the issue of who owns the technology arises. Implementing marine cloud brightening would require observation networks, models, ships and spraying equipment, international permits, and monitoring systems. These capabilities might be limited to a few major countries or corporations. If vulnerable countries cannot participate in decision-making, climate intervention could further exacerbate the issue of "climate justice."

Nonetheless, stopping research does not necessarily make things safer. On the contrary, being forced to hastily implement something during a future crisis without knowing what could happen might be more dangerous. The value of this research lies not in promoting marine cloud brightening but in increasing the materials to preemptively assess its effects and limitations. Geoengineering is precarious both as a taboo to ignore and as a panacea to embrace. What is needed is calm examination and transparent international rules.

The term "super El Niño" is not necessarily standardized as an official meteorological classification. However, the threat posed by a strong El Niño to society is real. Rising sea temperatures, extreme rain, droughts, heatwaves, and fluctuations in food prices are no longer news from distant countries. The world's climate system is interconnected, and we are entering an era where a single phenomenon can trigger multiple crises in succession.

Whitening clouds slightly might weaken that chain reaction. But who will be saved and who will bear the risk under those white clouds? The research highlights not only the potential of the technology but also a profound social question: how far humanity is willing to intervene in nature in the era of climate crisis.

Source URL

Phys.org: Referencing UC San Diego-led research, the context of treating Australian wildfires as a natural experiment, and the simulation results of marine cloud brightening.
https://phys.org/news/2026-07-geoengineering-tamp-super-el-nios.html

UC San Diego Today: Announcement from the research institution. Referencing research highlights, author comments, the 2019-2020 Australian fires and cloud brightening, and model verification using the 1997 and 2015 El Niños.
https://today.ucsd.edu/story/could-geoengineering-work-to-tamp-down-super-el-ninos

Science Advances: Original paper page. Referencing the paper titled "Targeted marine cloud brightening weakens subsequent El Niño" and DOI information.
https://www.science.org/doi/10.1126/sciadv.adx3012

WMO: Referencing the 2026 El Niño development outlook, extreme weather risks, and the point that "super El Niño" is not a standard operational classification.
https://wmo.int/news/media-centre/wmo-prepare-el-nino

NOAA Climate Prediction Center: Referencing the ENSO diagnosis as of June 2026, the establishment of El Niño conditions, and the outlook for strengthening through the winter of 2026-2027.
https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.shtml

WIRED: Referencing expert comments on the current research, political risks, concerns about side effects, and a general explanation of marine cloud brightening.
https://www.wired.com/story/dimming-the-sun-would-lower-risks-of-el-nino/

SRM360 LinkedIn article: Referencing the relationship between solar reflection methods and ENSO, and an example of related reactions observable on social media.
https://www.linkedin.com/pulse/how-would-solar-geoengineering-affect-el-ni%C3%B1o-srm360-org-zdbwe