Diamond dust geoengineering could cool Earth by 1.6°C at a $200 trillion cost

A new study published in Geophysical Research Letters says that spraying diamond particles in the stratosphere could help tackle global warming, but it comes with a jaw-dropping price tag.

Scientists from ETH Zürich built a 3D climate model showing that pumping 5 million tons of diamond dust into the stratosphere yearly could drop global temperatures by 1.6°C. Sandro Vattioni and his team examined seven materials—like sulfur dioxide, aluminum, and calcite—to determine which works best for solar geoengineering.

It turns out diamond dust came out on top. It reflects sunlight better, stays floating in the atmosphere longer, and doesn’t clump up as easily. Plus, since diamonds are chemically inert, they don’t cause acid rain—something that’s a big issue with sulfur-based options.

But here’s the catch: it’s expensive. Running the whole operation over the rest of the century could amount to nearly $200 trillion. And at $500,000 a ton, synthetic diamond dust is about 2,400 times pricier than sulfur. 

The idea got scientists talking. Critics like Daniel Cziczo, an atmospheric scientist at Purdue University, are worried about unexpected side effects and think research like this might pull focus away from cutting emissions.

Shuchi Talati, who runs the Alliance for Just Deliberation on Solar Geoengineering, says figuring out the physics behind these particles is important, and studies like this lay the groundwork for more extensive conversations about the potential impacts.

One interesting twist: the study showed that earlier research overlooked how sulfur absorbs certain types of light and traps heat, which could mess with climate patterns like El Niño. So, it’s not just a simple solution—it’s much more complicated than it seems.