Until the publication of a recent study , liquid and scCO2 were not considered in scenarios of the origin of life in submarine hydrothermal settings. Nonetheless, experimental simulations of prebiotic hydrothermal processes have often been conducted in reaction vessels with the vapor headspace; the adequacies of the experimental conditions have been questioned because the products inevitably derive from the gas as well as aqueous-phase reactions . Their reassessment in terms of the reproducibility in subseafloor scCO2 should be a meaningful approach to ascertain their realistic contributions to the origin of life. The Fischer-Tropsch-type hydrocarbon synthesis , for example, would be a promising reaction attainable in scCO2.