As the world grapples with the escalating threat of climate change, scientists are increasingly exploring geoengineering—deliberate, large-scale interventions in the Earth’s climate system—as a potential complement to emission reductions. While controversial, these techniques are gaining traction as global temperatures rise and natural ecosystems, such as coral reefs and Arctic ice, face irreversible damage.
The UK government’s Advanced Research and Invention Agency (ARIA) has committed £56.8 million to 21 geoengineering research projects over five years. These include marine cloud brightening (MCB), Arctic sea ice thickening and stratospheric aerosol injection (SAI), among others.
MCB involves spraying seawater into clouds to increase their reflectivity and reduce ocean surface temperatures. Dr Daniel Harrison in Australia is testing this method over the Great Barrier Reef, aiming to protect it from bleaching. Another application, studied by Jessica Wan in the US, suggests MCB could reduce the severity of heatwaves on land by cooling oceanic air masses that drift inland.
In the Arctic, Dr Shaun Fitzgerald’s team is experimenting with pumping seawater onto ice sheets to thicken them, potentially slowing summer melt and stabilising the region’s climate. Early trials in northern Canada show promising results.
Among the most debated ideas is SAI, which would involve injecting particles into the stratosphere to reflect sunlight. Although no material has yet been released, ARIA-funded tests are studying how particles might behave in such conditions. Scientists like Prof David Keith argue that, if carefully managed, SAI could offer temporary relief from warming, especially for vulnerable populations.
Other speculative ideas include deploying space-based shades to block a fraction of sunlight before it reaches Earth. While still theoretical, this concept has received ARIA funding for feasibility modelling.
Despite growing interest, public acceptance and international regulation remain significant hurdles. Past experiments have faced local opposition, and experts warn of the dangers if geoengineering is pursued unilaterally by rogue states or private individuals. Yet, with climate change accelerating, proponents argue that exploring these techniques transparently and scientifically is essential.
Geoengineering is not a substitute for cutting emissions, but it may offer a critical lifeline if used responsibly. As research progresses, the world may soon face difficult decisions about how to balance innovation with caution in the fight against climate change.
