[litespeed (OP)]

I recently ran across a study suggesting the last ice age was ended by deep sea volcanic activity? Does anyone have references or opinions on the general topic 'variability of ocean volcanic activity?

[Bass]

Volcanic activity along mid-oceanic ridges (I assume this is what you meant by deep ocean activity) is variable over time.  Spreading rates are not constant- meaning there is more activity during higher spreading rates (but I'm on a very slow computer so won't look up the numbers).