top of page

Marine Cloud Brightening: An Unorthodox Approach to Solving Climate Change

Updated: Jun 7

The Earth’s temperature has continued to rise as a result of human activities. The impact of climate change has been made apparent through the increase in severity and frequency of hurricanes, flooding, wildfires, heatwaves, and other major climate events.

Climate intervention practices like marine cloud brightening have recently been introduced as an alternative to cutting down on greenhouse gasses. Are these developments truly a solution or a distraction from putting an end to the real root of climate change?


Marine Cloud Brightening

In order to properly discuss the applications of marine cloud brightening, we must have a concrete understanding of how the heat transfer between the sun and the ocean works. The wind from the ocean’s surface stirs up sea salt crystals, which naturally gather moisture, rise, and form clouds. Clouds reflect some of the sun’s rays back into space and therefore deflect heat that would usually be absorbed by the ocean and Earth’s surface.

Marine cloud brightening mimics this natural process using a saltwater aerosol sprayer. High-tech machinery is used to spray saltwater aerosols into shallow marine clouds to brighten them. This increases the cloud’s albedo, reflection of sunlight, and reduces the amount of heat absorbed by ocean water. Therefore, this technique has the potential to make significant progress in halting further ocean warming.

Don’t get too excited — this is a long-term process that could take weeks or even months of spraying before ocean water temperatures become optimal. However, marine cloud brightening has the potential to reduce ocean temperatures enough to relieve coral bleaching stress over vast portions of the Great Barrier Reef and to return atmospheric temperatures to what they once were before the overuse of fossil fuels.

Research & Refinement

Marine cloud brightening is a technique that is still in need of refinement. Only through more research and testing of the technique on marine clouds can scientists truly make inferences about the long-term feasibility and potential risks of marine cloud brightening. Graham Feingold, a researcher with NOAA’s Chemical Sciences Laboratory, said, “Interest in MCB is growing, but policymakers currently don’t have the information they need to reach decisions about if and when MCB should be deployed.”

One of the most challenging aspects of marine cloud brightening is perfecting the size of the aerosols emitted. Researchers need to develop sufficient evidence that appropriately sized particles can consistently be created and delivered to clouds over a large enough area to efficiently and cost-effectively cool the ocean below. Scientists must also address the concerns that trying to manipulate clouds may cause clouds to thin which can increase precipitation and result in greater ocean heating.

The Drawbacks to MCB Testing

Recently, some drawbacks have been discovered in outdoor experimentation with marine cloud brightening. Officials in Alameda, California have recently told scientists to stop testing a marine cloud brightening device due to health concerns raised by the public.

On April 2, 2024, the University of Washington began the first outdoor U.S. study of marine cloud brightening devices. The devices were placed on the flight deck of a decommissioned aircraft carrier (the U.S.S. Hornet) docked in Alameda in San Francisco Bay. On May 4, only a month later, the City of Alameda instructed the researchers to stop because of possible health concerns. In a Facebook post the city officials wrote, “City staff are working with a team of biological and hazardous materials consultants to independently evaluate the health and environmental safety of this particular experiment. The City is evaluating the chemical compounds in the spray to determine if they are a hazard either inhaled in aerosol form by humans and animals, or landing on the ground or in the bay.”

Although the spray from previous experiments has never shown any threat to the health of humans, animals, or the environment, the University of Washington Research Program has happily cooperated with the city and halted their study until further notice. They also released a statement saying the aerosols they emitted “operate well below established thresholds for environmental or human health impact for emissions.” All in all, it will take further experimentation and research to determine if marine cloud brightening is feasible method to combat ocean heating in the future.

Potential Risks of Marine Cloud Brightening

The big question is, should we dedicate more resources and effort to reversing climate change or preventing further climate change? Many environmentalists are worried that artificially cooling the planet through MCB is not a solution because it does not directly address the root cause of climate change, the combustion of fossil fuels.

There is also a possibility that marine cloud brightening can alter the environment on a local scale. There are potential side effects that have yet to be studied including changing ocean circulation patterns and precipitation patterns.

Marine cloud brightening may just be too sensitive of a process to effectively create large scale change. There are a host of different variables that must be considered before implementing marine cloud brightening techniques. Some clouds are more susceptible to aerosol injections than others and how a cloud responds to being manipulated relies on the weather and background aerosol conditions. The optimal particle size and amount is also dependent on cloud properties that can change constantly as they drift through the air.

Marine cloud brightening seems like a promising technique to reduce the impacts of climate change, but its potential environmental impacts have yet to be thoroughly researched. Only with time and experimentation will experts be able to come to a conclusion on whether or not this technique will ultimately benefit our planet or harm it.



Marine cloud brightening, a solar radiation modification method that injects salt aerosols into the air to thicken clouds and deflect the sun’s rays, is a potential solution to cooling our oceans and atmospheres. Further research is still necessary to refine the process and explore potential side effects and risks. Currently, some studies are currently being cancelled to investigate the impact of marine cloud brightening machinery on human health. Overall, marine cloud brightening is a complex process that may take decades to refine until it is a suitable and effective technique to combat climate change.

Stay updated and active by following the Environmental Defense Initiative on Medium and our social media platforms!

Author: Cassidy Fisher

Editor: Emma Mazzotta


0 views0 comments

Recent Posts

See All


bottom of page