Thermal Effects of Magma Intrusion on Ocean Temperatures Through Ice Ages, with Particular Reference to Interglacial Events

Abstract

Recent observations are used to crudely quantify and scale the direct heating of the global ocean surface by submarine volcanism. These suggest a current submarine magma budget that is substantially greater than the prevailing consensus. The current ocean heating effect is estimated at c. 0.7W/m2. Interglacial events are geologically sudden and predictably cyclical, overtly caused by the combined effect of Milankovitch cycles. Several possible causes for interglacial warmings arising from these cycles have been proposed, and rejected as inadequate. These are summarily reviewed. It is concluded, in the absence of other capable causes, and in particular given the evidence of continued ocean warming throughout the Dryas cooling events, that ice age interglacial events are probably caused by a sustained increase in the rate of submarine volcanic heating of the oceans. The primary cause of increasing emissions is suggested as the rising levels of solid gravitational tides caused by the combined orbital forcing of all three main Milankovitch cycles. These tides are at their largest during interglacial warmings. How the dominant climate control system of oceanic feedback responds to this internal perturbation change is also discussed. In particular how the upper equilibrium temperature of an interglacial period is imposed by this control.