Fig. 5. Method and calculations for the annual amount of reduced phosphorus sourced from lightning strikes vs. meteorite influx during the Hadean and early Archean.

a Flowchart showing the steps in calculating the annual formation of reduced phosphorus from lightning strikes on early Earth (see main text and Supplementary Discussion 2). b Flowchart showing the steps in calculating the annual flux of reduced phosphorus from meteorites on early Earth (see also main text and Supplementary Discussion 3). c Mass range of reduced phosphorus produced per year from fulgurite-forming lightning strikes and meteorites as calculated in (a, b). Inset shows model inputs for atmospheric pCO₂ in bars, lightning strikes per km² per year, and annual total P in kg per year from meteorites¹¹ as a function of time.