A new study explains how carbon dioxide cools the upper atmosphere—and warms earth below

Even as temperatures rise on Earth’s surface and in the lower atmosphere, the planet’s upper atmosphere has cooled dramatically. This paradoxical pattern is a well-known sign of humanity’s climate impacts—but until now, the underlying physics has remained a mystery. In a new study, researchers from Columbia University describe the phenomenon’s mechanics, illuminating how it is largely determined by the way carbon dioxide (CO2) interacts with different wavelengths of light.