A new paper by leading climate scientists and policy experts finds that indirect greenhouse gases account for roughly 15% of current global warming from human emissions yet remain largely absent from climate policy. These overlooked pollutants, including carbon monoxide, non-methane volatile organic compounds, nitrogen oxides, and molecular hydrogen, do not warm the climate directly. Instead, they alter atmospheric chemistry in ways that increase levels of methane, ozone, and other greenhouse gases, which results in increased warming. Reducing these emissions represents an overlooked opportunity to slow warming while delivering air quality benefits.