Shutterstock
A recent study has uncovered exactly how the method of cloud ‘engineering’ works and its effectiveness as a potential tool for climate cooling.
2023 was the hottest year ever recorded, and while countries find ways to ramp up decarbonisation initiatives, one method of offsetting global warming effects in the meantime could be through marine cloud brightening (MCB), otherwise known as marine cloud engineering.
In MCB tiny particles or aerosols are injected into marine clouds to make them even brighter and more reflective. Seeding these clouds with aerosols increases the amount of sunlight they reflect, thus redirecting incoming solar radiation back into space. It is thought that this ‘cooling’ method could contribute towards offsetting global warning.
MCB is already in use. For example, experiments are being carried out in Australia in an attempt to reduce bleaching on the Great Barrier Reef.
In a bid to discover just how effective MCB is and the ways in which this method creates a cooling effect, models have traditionally focused on on aerosol injections’ ability to brighten clouds and the amount of sunlight reflected back into space.
However, new research by the universities of Birmingham, Edinburgh, Reading and Leeds, as well as international partners, has found that MCB works primarily by increasing the amount of cloud cover, which accounts for 60% to 90% of the cooling effect.
Shutterstock
To understand the effect of aerosols on clouds and sunlight, the research team created a ‘natural experiment’ utilising aerosols from the Kilauea volcano eruption in Hawaii. This enabled them to study the interactions between these natural aerosols, clouds and climate.
Using machine learning and historic satellite and meteorological data, the team developed predictors to discern the direct influence of volcanic aerosols on cloud behaviour.
Their findings revealed that the cloud cover relatively increased by up to 50% during the periods of volcanic activity, producing a cooling effect of up to -10W/m-2 regionally.
Global heating and cooling is measured in watts per square metre, with a negative figure indicating cooling. For context, doubling CO2 typically yields a warming effect of approximately +3.7W/m-2 globally.
As such, the research suggests that particle pollution may have increased cloud cover and counteracted climate warming more than previously thought.
But the lead author of the research study, Dr Ying Chen of the University of Birmingham, is keen to point out that while MCB could be useful, this method does not address the underlying causes of human-generated global warming.
“It should therefore be regarded as a ‘painkiller’, rather than a solution, and we must continue to improve fundamental understanding of aerosol’s impacts on clouds, further research on global impacts and risks of MCB, and search for ways to decarbonise human activities,” said Chen.
This research comes alongside increased interest in cloud engineering around the globe. For instance in the UK, UK Research and Innovation has recently launched a £10.5m research programme looking at informing policymakers on solar radiation management approaches, including MCB, while the Advanced Research and Invention Agency is focused on researching technologies for climate and weather management.
