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Researchers study a technique that uses salt particles to make marine clouds more reflective, in an experimental attempt to reduce some of the warming in vulnerable areas of the planet.
Scientists from the United Kingdom are studying a technique that seeks to increase the brightness of marine clouds with salt particles, so that they reflect more sunlight back into space.
The method, known as marine cloud brightening, is analyzed as a possible temporary intervention to reduce some of the warming in vulnerable areas, without replacing the reduction of greenhouse gas emissions.
The proposal is based on a principle of cloud physics: spraying very small droplets of seawater into the atmosphere over oceanic regions, so that the salt acts as a condensation nucleus.
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Under certain conditions, these particles favor the formation of more droplets within the clouds.
With a greater number of smaller droplets, the tendency is for the cloud to reflect more solar radiation.
The topic has begun to be investigated by research groups in light of global difficulties in limiting the increase in the planet’s average temperature.
Even so, experts involved in these studies emphasize that the technique does not address the cause of the warming.
The proposed function would be to temporarily reduce some of the solar radiation reaching the surface, while decarbonization measures remain the central axis of climate policy.
How salt can alter the brightness of marine clouds
Marine cloud brightening attempts to reproduce, in a controlled manner, a phenomenon that already occurs over the oceans.
The action of the wind and the breaking of waves release salt particles into the air, and these aerosols can influence the formation of low clouds.
The studied intervention seeks to amplify this effect through the release of fine mists of seawater.
In practice, researchers are evaluating whether sprayers installed on platforms, vessels, or coastal structures could release particles of the appropriate size.
If the process works as predicted in models and controlled tests, these particles could favor the formation of clouds with a greater capacity to reflect sunlight.
With less energy absorbed by the surface, the affected region could experience temporary cooling.
This mechanism is related to the so-called Twomey effect, a concept used in atmospheric science to describe the relationship between small droplets and greater reflection of solar radiation.
The theory has been known for decades, but its deliberate application in an open environment still depends on testing, climate modeling, and risk assessment.
Project REFLECT investigates climate geoengineering in the United Kingdom
One of the ongoing projects in this area is REFLECT, led by the University of Manchester in partnership with the National Centre for Atmospheric Science.
The initiative received funding from the Advanced Research and Invention Agency, ARIA, a British public body created to support high-risk research with high scientific potential.
The name REFLECT is an English acronym associated with a program that evaluates spraying technologies and their impacts on local albedo changes.
In climate science, albedo is the ability of a surface or atmospheric formation to reflect light.
The project’s objective, according to the University of Manchester, is to understand if this type of intervention can be safely tested and if its effects would be measurable.
The team works with laboratory experiments, development of sprayers, and computational models.
Among the points evaluated are the ideal size of salt particles, the energy efficiency of the equipment, and the behavior of the aerosol plume in maritime environments.
This data is considered necessary before any advancement to external testing.
Hugh Coe, professor of atmospheric composition at the University of Manchester and project leader, states that cloud brightening could offer a temporary cooling effect but does not replace the reduction of carbon emissions.
The assessment summarizes the position adopted by the researchers: studying the technique does not mean treating it as a definitive climate solution.
Salt particle size is a central point of the research
One of the technical difficulties lies in defining the exact size of the particles released into the air.
When they are too large, they can attract too much water and favor larger droplets, which reduces the expected brightening effect.
In some scenarios, there is also the possibility of contributing to drizzle formation.
Particles that are too small, on the other hand, may not grow enough to act as cloud droplets.
In this case, the spraying would not produce the expected increase in brightness.
For this reason, a significant part of the research takes place in simulation chambers and atmospheric models before any open environment experiments.
The University of Manchester reports that the team intends to use cloud chambers to test how different particles compete for water vapor.
The results are expected to feed climate models used to estimate impacts on larger scales, including effects on temperature, rainfall, and atmospheric circulation.
Open environment tests depend on environmental assessment
Experiments outside the laboratory, if approved, should occur in a limited, temporary, and controlled manner.
ARIA reports that external tests funded by the program must undergo environmental impact assessment, public consultation, and independent oversight before being conducted.
This requirement exists because climate interventions can produce effects beyond the area where they are applied.
The climate system connects oceans, winds, rainfall, and temperatures in different regions.
Therefore, an action designed to cool a specific point needs to be evaluated also concerning possible indirect effects.
Recent studies on cloud brightening indicate that the climate response can vary depending on the region, the scale of the intervention, and the warming scenario considered.
In some simulations, the technique appears associated with a reduction of extreme heat in certain areas.
In others, it loses effectiveness or may contribute to undesirable changes in distant locations.
Solar geoengineering involves climatic and social risks
Cloud brightening is part of a set of proposals called solar radiation modification.
These techniques aim to reflect part of the Sun’s light to temporarily reduce warming.
The topic is approached with caution by researchers and scientific bodies as it involves environmental, political, and social risks that are not yet fully understood.
Among the concerns cited by specialists are possible changes in rainfall patterns, impacts on marine ecosystems, unequal regional effects, and the absence of consolidated international rules.
Another point discussed is the so-called moral hazard, a concept used to describe the possibility of a palliative technology reducing the pressure for emission cuts.
ARIA and the University of Manchester state that the studies aim to generate scientific evidence to assess whether these techniques are viable, safe, or should be discarded.
Mark Symes, program director of the British agency, stated that rapid decarbonization remains the only long-term solution to climate change.
Technique is still studied as an experimental tool
The scientific interest in cloud brightening lies in the difference between the apparent simplicity of the method and the complexity of its application.
Spraying saltwater into the sky may seem like a straightforward action, but the process involves cloud microphysics, spray engineering, climate modeling, environmental assessment, and public governance.
In regions like the Great Barrier Reef in Australia, research is already analyzing the use of cloud brightening as a possible regional tool against marine heatwaves and coral bleaching.
Even in these cases, studies keep the method in an experimental phase and subject to rigorous scientific evaluation.
The issue under analysis is not limited to the technical ability to brighten clouds with salt.
For researchers in the field, the debate also involves safety, transparency, regional impacts, and climate responsibility.
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