The amount of heat trapped in the atmosphere from a proportionate increase in CO2, which scientists refer to as radiative forcing, has long been thought of as a constant. However, a study led Brian Soden at UM found that carbon dioxide becomes a more potent greenhouse gas as more of it is released into the atmosphere.

Researchers used state-of-the-art climate models and “offline” radiative flux calculations to analyze the effect increasing CO2 has on the upper part of the atmostphere, known as the stratosphere, which cools with increasing CO2 concentrations. They found that this stratosphere cooling causes subsequent increases in CO2 to have a larger heat-trapping effect than previous increases.

• Brian Soden