In an ambitious and controversial bid to fight global warming, UK scientists are preparing to test ways of altering cloud formations to reduce sunlight reaching Earth. Backed by £57 million from the UK government’s Advanced Research and Invention Agency (ARIA), these geoengineering trials could begin outdoors by 2027.
One key project involves Marine Cloud Brightening, a method where saltwater is sprayed into the sky to increase the reflectivity of low-altitude clouds. By encouraging cloud droplets to coalesce, the technique aims to reflect more sunlight back into space—cooling the planet in the process.
According to Professor Mark Symes, the programme director at ARIA, the changes may not be visible from the ground but will be measurable with airborne equipment. Trials will begin with indoor testing before moving outdoors in the winter of 2027–2028, in locations yet to be determined across the UK.
Initial outdoor tests will span an area of about 330 feet wide, with the possibility of expanding to several miles by the decade’s end. This effort represents one of the UK’s most daring scientific steps toward directly manipulating the climate system in the name of climate protection.

