Scientists have a radical plan to cool Earth—Dim the Sun
26 Apr 2025

In an ambitious bid to fight climate change, the UK government is gearing up for a series of solar geoengineering trials.

The experiments will test different techniques, including injecting aerosols into the atmosphere and brightening clouds, to reflect sunlight.

The Advanced Research and Invention Agency (ARIA) will fund the trials with around $66.5 million, making the UK one of the biggest funders of solar geoengineering research, according to the Guardian.

Controversial yet essential: The need for solar geoengineering
Climate crisis

The scientific community remains divided over drastic measures like solar geoengineering, given the risks involved.

But as we near critical warming tipping points where the effects of climate change are believed to be irreversible, some experts argue that all options should be explored.

Mark Symes, ARIA's program director, emphasized this urgency by stating "Our current warming trajectory makes a number of such tipping points distinctly possible over the next century."

Stratospheric aerosol injection: A potential solution
Aerosol injection

The foremost method suggested for dimming the Sun is stratospheric aerosol injection.

It entails injecting massive quantities of tiny particles, like sulfur dioxide, into the atmosphere to reflect some sunlight back into space.

Another method being explored is marine cloud brightening which sprays sea salt aerosols on clouds to promote water droplet formation and make them denser.

Real-world evidence supports solar geoengineering strategies
Evidence

Despite the risks, real-world data indicates these geoengineering strategies could work.

Jim Haywood, an atmospheric scientist at the University of Exeter, pointed to volcanic eruptions as proof that sulfur clouds can cool the Earth and ash can brighten clouds—supporting both aerosol injection and cloud brightening ideas.

However, critics warn these methods could lead to a "termination shock," where the planet rapidly heats up again once aerosol release ceases.