By Dr. Celeste Rahman
Imagine dimming the sun just slightly — enough to cool the Earth by a degree or two. The idea sounds like science fiction, but solar geoengineering is rapidly moving from thought experiment to serious policy conversation. By scattering reflective particles in the stratosphere, scientists could reduce global temperatures, mimicking the cooling effects of volcanic eruptions. Advocates see it as a potential stopgap in the fight against climate change. Critics call it a dangerous gamble with planetary systems.
The Volcano Analogy
When Mount Pinatubo erupted in 1991, it released sulfur dioxide that cooled global temperatures by about half a degree Celsius for nearly two years. Solar geoengineering proposes to replicate that effect deliberately. The principle is simple: less sunlight reaching the surface means less warming. But simplicity at the level of physics does not translate to simplicity in politics or ethics.
Unlike volcanic ash, which dissipates naturally, engineered cooling would require continuous upkeep. If abruptly stopped, temperatures could spike back with devastating speed — a “termination shock” that ecosystems and societies may not withstand.
Risks in the Stratosphere
The science warns of unintended consequences. Altered rainfall patterns could trigger droughts in some regions while flooding others. The chemistry of the upper atmosphere could shift, further depleting the ozone layer. And the global climate is not a uniform machine; interventions may help some countries while harming others.
Which raises the central dilemma: who gets to control the thermostat? A coalition of wealthy nations? The United Nations? A single desperate country facing climate catastrophe? Unlike emissions cuts, which demand global coordination, geoengineering could theoretically be deployed unilaterally, with planetary consequences.
Promise in a Warming World
Supporters argue that the world needs every tool possible to stay within safe temperature limits. Solar geoengineering could buy time while societies decarbonize and adapt. For communities already facing rising seas or unbearable heat waves, the appeal is clear: a few tenths of a degree could mean survival.
But relying on geoengineering risks moral hazard — the temptation to delay the hard work of reducing emissions. Just as a crash diet doesn’t replace healthy living, reflective aerosols can’t substitute for ending fossil fuel dependence.
A Global Conversation, Not a Silver Bullet
The real danger may lie not in the science itself but in the absence of governance. Without transparent research, democratic debate, and international agreements, solar geoengineering could become a weapon of geopolitical mistrust.
Cooling the planet may be technically possible, but warming the debate is essential. Societies will need to weigh not only risks and benefits but values: fairness, justice, and responsibility for a shared atmosphere. Like all climate solutions, geoengineering is not just about science. It is about who we are willing to become in the face of planetary crisis.
