British scientists have revealed a controversial plan to sprinkle salt into the sky in an effort to slow climate change.

Researchers from Manchester University are testing whether a fine mist of salt water could be sprayed into clouds to make them more reflective.

This process, known as 'cloud brightening', could help clouds act like natural sunscreen, bouncing more radiation back into space and keeping Earth cool.

Previous studies have suggested that this kind of geoengineering could have disastrous effects, wreaking havoc on global weather patterns.

However, as climate change drives massive and increasingly deadly disruptions to global weather patterns, scientists are starting to consider more drastic solutions.

Scientists at the 'Reflect' project are already making small–scale laboratory tests of the technology as part of a £6 million project to halt global warming.

If their tests are successful, the researchers plan to make the first open–air trial in the UK within the next two years.

That experiment could see plumes of salt spray injected into the air in a path covering several miles of Britain's coastline.

Lead researcher Professor Hugh Coe, Director of the Manchester Environmental Research Institute, says he doesn't think cloud brightening is the 'ultimate solution' to climate change.

The Reflect project is just one of the 22 projects backed by a £57–million programme, funded by the Advanced Research and Invention Agency (Aria).

These research groups are investigating high–risk, high–reward options for slowing down the progress of climate change.

The basic principle behind Reflect is that brighter clouds reflect more sunlight, balancing out the greenhouse gases we are already adding to the atmosphere.

This is a principle scientists understand extremely well, because it is a phenomenon which is already happening all around the planet.

Large volcanic eruptions inject huge amounts of aerosols into the atmosphere, producing an increase in cloud cover and dropping global temperatures.

On the smaller scale, the plumes of smog churned out by factories and the trails of pollution left by diesel–guzzling tankers actually produce a huge cloud–brightening effect.

In fact, efforts to clean up shipping's climate footprint have made clouds over the Northeastern Pacific and Atlantic nearly three per cent less reflective in the last decade – unintentionally speeding up climate change.

Cloud brightening aims to recreate this process in a safe way using harmless sea salt, which is already found naturally in the atmosphere.

However, lead researcher Professor Hugh Coe, Director of the Manchester Environmental Research Institute, says cloud brightening isn't the 'absolute solution' for climate change.

'The solution in the long–term is to not have as much carbon in the atmosphere,' says Professor Coe.

'What makes the planet warm is carbon, what cloud brightening does is provide a breathing space to allow us to get those emissions down – but that's only if we can't move fast enough.'

But with emissions currently showing no sign of reducing fast enough to cap global warming, Professor Coe says it is time to fully understand our last–resort option.

He says: 'If we do need to do something like this, then we had better know what we are doing.

'Because we don't want to make a bigger problem by doing something else.'

Currently, Professor Coe and his colleagues are trying to find the 'Goldilocks' size for their saltwater particles.

Inside a three–storey stainless steel 'cloud chamber', the researchers are honing their methods for producing fine salt–water aerosols.

If the droplets are too large, they tend to replace the particles that are already in the atmosphere, hampering the natural process of cloud formation.

Too small, and the drops won't properly 'activate' and the cloud won't get bright enough to make a difference.

Next year, the research will scale up to a larger, but still controlled, environment such as a polytunnel.

Once Aria gives Professor Coe's findings the green light, the team will move to their first outdoor testing.

A plume of salt water would be deployed for 'a few minutes' in an area a few miles off the British coastline.

Drones and Lidar would be used to monitor the plume's movements and to ensure that it doesn't spread further than expected.

Professor Coe stresses that the testing would be 'very small–scale' and that the amounts of particles added would be far smaller than the normal levels of pollution over land.

Meanwhile, the large–scale impacts of geoengineering will be studied using computer models built from their findings.

In the future, if the method continues to prove safe and effective, large regions of low–lying clouds in the Pacific and Atlantic could be targeted for brightening.

This could help keep global warming in check and prevent the worst consequences of climate change while the world transitions away from fossil fuels.

However, geoengineering has also been an exceptionally controversial proposition.

Many scientists argue that these methods only give polluting businesses and governments an excuse not to cut their emissions, dealing with the symptoms of climate change without tackling the cause.

Likewise, research has also suggested that the consequences of geoengineering could be far more widespread than intended.

A study conducted by Columbia Climate School found that a type of solar geoengineering called 'stratospheric aerosol injection' (SAI) could wreak havoc on global weather patterns.

If the aerosols were released in the polar regions, they would likely disrupt tropical monsoon systems, which could have an effect on sea levels, they found.

Meanwhile, releases concentrated in equatorial regions could affect the jet stream and disrupt atmospheric circulation patterns that conduct heat towards Earth's poles.

Dr Ying Chen, an expert on cloud brightening from the University of Birmingham who was not involved with the study, told the Daily Mail: 'Change the solar radiation heating at one place, may lead to change of atmospheric pattern in other places.

'But what it could be and how large it is, we are not sure yet. More research is urgently needed.' 

Professor Coe doesn't deny that cloud brightening would change the weather, but argues that we need to consider how dangerous doing nothing might be as the alternative.

He says: 'If you do things that are large scale, you will influence weather patterns, we're already doing that with climate change.

'The question is whether there is overall improvement versus the problem we're already creating already. We want to make sure those predictions are robust as they can be, otherwise don't do it.'