The significance of impact-induced hydrocarbon soot aerosols in global climate change and extinctions

Large meteoroid impacts have punctuated the Phanerozoic Eon, with the Cretaceous–Paleogene (K–Pg) impact as the most prominent example. While some impacts triggered global climate change and mass extinctions, others produced only limited environmental effects. These events injected aerosols into the stratosphere, reducing sunlight, cooling the climate, and decreasing precipitation. Major aerosol types include sulfuric acid (from sulfur-rich rocks), soot (from organic-rich target rocks and wildfires), and dust (from pulverized rock), though their relative roles remain uncertain. Here we quantify the production of each aerosol type and calculate surface temperature anomalies for the nine largest impact craters of the past 250 Myr using target rock lithologies and climate model outputs. Our cross-plot analysis of temperature and extinction magnitude reveals that soot generated from organic carbon in target rocks is likely the primary driver of impact-induced mass extinctions. Additionally, we estimated the frequencies of impact-generated mass extinctions for each aerosol type using two cases: one major extinction (>60 % species loss) in 540 million years (K-Pg) and two major-moderate extinctions (>20 % species loss) in 250 million years (K-Pg and mid Norian). Our findings demonstrate that soot formed from sedimentary rocks most accurately matches the observed frequencies—one major and two minor-major extinctions. These results establish that the severity of cooling and extinction triggered by meteoroid impacts is primarily determined by the abundance of buried organic carbon in the target rocks, underscoring the target sensitivity of impact-induced climate effects. • Soot from ignition of hydrocarbons by impacts is the main cause of mass extinctions. • The degree of cooling depends on amounts of buried hydrocarbons in target rocks. • Hydrocarbon soot has a greater influence on global extinctions than other aerosols. • Small variations in composition of impact sites result in different bio-evolution. • Organisms themselves have prepared the triggers for impact-generated extinctions.