Our industrialized society releases many different pollutants into the world. Combustion in particular creates aerosol matter, including black carbon. Although it only makes up a few percent of aerosol particles, black carbon is particularly problematic because of its ability to absorb heat and hinder the heat-reflecting abilities of surfaces like snow. That's why it's important to know how black carbon interacts with sunlight. Researchers have quantified the refractive index of black carbon to the most precise measure that could influence climate models. There are many factors that cause climate change; some are well-known, such as carbon dioxide emissions from fossil fuel combustion, sulfur dioxide from cement production, or methane emissions from animal husbandry. Black carbon aerosol particles, also from combustion, are less widely reported but are of particular importance. Black carbon, essentially soot, is very good at absorbing heat from sunlight and storing it, adding to the atmospheric heat. At the same time, dark colors are less effective at reflecting light and therefore heat, as black carbon covers lighter surfaces, including snow, reducing the potential for those surfaces to reflect heat back into space. (University of Tokyo)