Cloud brightening aims to reflect more sunlight and prevent warming. Photo / 123RF
Cloud brightening aims to reflect more sunlight and prevent warming. Photo / 123RF
Scientists are considering cloud-brightening to reflect sunlight as a method to prevent climate change.
The British Government’s research agency has allocated £50 million ($111.6m) for experiments, including aerosol injections.
Geoengineering projects are controversial but may be necessary due to slow reductions in carbon dioxide levels.
British scientists are considering a novel way to prevent runaway climate change: brightening clouds to reflect sunshine.
Experiments to dim sunlight to fight global warming will be given the green light by the Government within weeks.
Outdoor field trials, which could include injecting aerosols into the atmosphere or brightening clouds to reflect sunshine, are being considered.
Aria, the UK Government’s advanced research and invention funding agency, has set aside £50 million ($111.6m) for projects that are set to be announced in the coming weeks.
Professor Mark Symes, the programme director for Aria (Advanced Research and Invention Agency), said there would be “small, controlled outdoor experiments on particular approaches”.
“We will be announcing who we have given funding to in a few weeks and when we do so, we will be making clear when any outdoor experiments might be taking place,” Symes said.
“One of the missing pieces in this debate was physical data from the real world. Models can only tell us so much.
“Everything we do is going to be safe by design. We’re absolutely committed to responsible research, including responsible outdoor research.
“We have strong requirements around the length of time experiments can run for and their reversibility and we won’t be funding the release of any toxic substances to the environment.”
Geoengineering projects which seek to artificially alter the climate have proven controversial, with critics arguing they could bring damaging knock-on effects and be an unhelpful distraction from lowering emissions.
However, scientists are increasingly concerned that carbon dioxide levels are not falling fast enough and that further action may be needed to prevent catastrophic warming.
One major area of research is sunlight reflection methods, which includes stratospheric aerosol injection, whereby tiny particles are released into the stratosphere to reflect sunlight.
Another potential solution is marine cloud brightening: ships would spray sea-salt particles into the sky to enhance the reflectivity of low-lying clouds.
Scientists are trying different ways to dim sunlight. Photo / 123rf
Shipping fumes
In recent decades, experts noticed that the clouds above shipping routes were far brighter than usual, as pollution caused them to become more reflective, bringing an overall dimming effect.
This cooling from shipping fumes was so marked that when international regulations were enacted to curb sulphur dioxide emissions in 2020, it caused a spike in global warming, scientists believe.
Prof Jim Haywood, of Atmospheric Science at the University of Exeter, said: “If you inject small particles into clouds you can brighten them, hence reflecting more sunlight back out to space.
“How do we know this could work? Well, there are a couple of very strong pieces of evidence.
“Ship emissions from the smoke stack into the marine environment lead to bright lines in clouds over the ocean.
“Then there was a volcanic eruption in Iceland in 2014 which spilled out a lot of sulphur dioxide. What this does is it brightens clouds and cools the planet. What we need to do is some form of field experiments.”
Seeding cirrus clouds
Other ideas for geoengineering include seeding cirrus clouds to allow more heat to escape into space. Currently, the wispy high-altitude clouds act as a blanket, trapping in heat.
Dr Sebastian Eastham, a senior lecturer in sustainable aviation at Imperial College London, said: “Every time you fly, sulphur, which is naturally present in jet fuel, is emitted into the lower most stratosphere causing a small cooling effect.
“Similarly, aircraft contrails cause accidental cirrus cloud modification but in this case accidentally causing, rather than preventing or thinning, cirrus clouds.
“This points to the fact that it’s theoretically possible (to cool the planet) with current day technology but there are many practical questions that would need to be answered before they could be done at scale.”
Experts are hopeful that if experiments prove a success, they could be scaled up and implemented within 10 years.
As well as outdoor experiments, Aria will also be funding new modelling studies, indoor tests, climate monitoring and gauging public attitudes to geoengineering.
