Carbon in Color: Metaphors Shaping Science, Policy, and Imagination

Abstract Carbon is one of the most abundant elements on Earth, circulating through forests, soils, oceans, wetlands, the atmosphere, and even ice. Scientists and communicators have developed a palette of “carbon colors” to capture this diversity: green for terrestrial ecosystems, blue for coastal and marine habitats, teal for freshwater wetlands, black for soot and char, brown for light‐absorbing aerosols, and red for snow algae. These colors are not formal scientific categories, nor are they used in carbon markets or accounting frameworks. Instead, they act as metaphors—simple, vivid labels that make complex processes legible to policymakers, investors, and the public. In this Commentary , we introduce the carbon color system, explain the environments and processes behind each shade, and explore how colors shape science and storytelling. We also highlight emerging candidates such as plastic and viral carbon, and consider what happens when carbon “changes color” as it moves between ecosystems. The palette continues to evolve, reminding us that metaphors influence which processes capture attention, guide investment, and inspire imagination in the global response to climate change.