Global rate and distribution of H 2 gas produced by serpentinization within oceanic lithosphere

It has recently been estimated that serpentinization within continental lithosphere produces H 2 at rates comparable to oceanic lithosphere (both are ~10 11 mol H 2 /yr). Here we present a simple model that suggests that H 2 production rates along the mid‐oceanic ridge alone (i.e., excluding other marine settings) may exceed continental production by an order of magnitude (~10 12 mol H 2 /yr). In our model, H 2 production rates increase with spreading rate and the net thickness of serpentinizing peridotite (S‐P) in a column of lithosphere. Lithosphere with a faster spreading rate therefore requires a relatively smaller net thickness of S‐P to produce H 2 at the same rate as lithosphere with a slower rate and greater thickness of S‐P. We apply our model globally, incorporating an inverse relationship between spreading rate and net thickness of S‐P to be consistent with observations that serpentinization is more common within lithosphere spreading at slower rates. Oceanic production may be ~10 11 mol H 2 /yr, larger than widely recognized Faster‐spreading lithosphere may produce significant quantities of H 2 Oceanic (versus continental) lithosphere likely dominates H 2 production globally