A cloud shades the ocean. Break it apart, and more sunlight reaches the water. The ocean warms. Across enough of the Earth, that simple change could have enormous consequences.

Tapio Schneider studies how clouds respond to a warming planet. At Caltech, he works to understand what happens inside them and how those changes affect the climate we depend on.

In a 2019 study, he and his colleagues found that marine cloud layers could break apart under very high carbon dioxide concentrations. In their simulations, losing that shade caused substantial additional warming. The study revealed a possible danger, though the conditions required were far beyond those at the time and the precise threshold remains uncertain.

Clouds are difficult to get right. The air moving inside them is too small in scale for global climate models to capture directly. Yet those movements help determine how much sunlight reaches the Earth. A weakness in our understanding of a cloud becomes uncertainty about our future.

Schneider leads a team building a climate model that learns from observations and detailed simulations. The goal is to give us a clearer picture of what lies ahead. How much rain might a city need to handle? How long could a drought last? A reservoir built today may still be serving people a century from now.

I photographed him at the Athenaeum at Caltech. I am drawn to work like his because the distance between an equation and a human life can be shorter than we think. Better predictions give people time to prepare. Schneider is working to make those predictions more dependable.