Global rate and distribution of H₂ gas produced by serpentinization within oceanic lithosphere

It has recently been estimated that serpentinization within continental lithosphere produces H₂ at rates comparable to oceanic lithosphere (both are ~10¹¹ mol H₂/yr). Here we present a simple model that suggests that H₂ production rates along the mid-oceanic ridge alone (i.e., excluding other marine settings) may exceed continental production by an order of magnitude (~10¹² mol H₂/yr). In our model, H₂ 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 H₂ 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.