Fig. 3. Estimate of hydrogen concentration in the core based on single-stage core formation models.

Three solid lines show our estimates of the hydrogen content in the core as a function of residual H₂O abundance in silicates (= present-day BSE water content) at the labeled P–T conditions^2–4. The BSE water content depends largely on the average mantle abundance (lower horizontal axis)^18,64,65. Even a modest amount of water in the present-day mantle¹⁸ and resulting 687 ppm H₂O in the BSE suggest 0.32–0.61 wt% H in the core. The corresponding ocean mass of water (OC) that includes an equivalent amount of hydrogen is also indicated (right vertical axis).