Volcano Sea

Since we regularly get questions about this type of thing, I wanted to repost this excellent post from Erik Klemetti's blog 'Eruptions.'

"I recently read a post about how humans couldn't be to blame for the warming of the oceans.
The "logic" of their post was this:

We see water getting warmed by magma at volcanoes worldwide, like Taal andRuapehu.
The bottom of the ocean is covered in volcanoes, whether it be seamounts or the mid-ocean ridge system.
Volcanoes at the bottom of the ocean must heat up the ocean water (like in crater lakes), so humans aren't to blame.
There are a number of ways to attack this poor reasoning, but I'll try to go with the ones I think are most convincing.