Don't we have a lack of knowledge of our oceans to be making claims about volcanoes?
The reason I ask this is based on the debate between Ian Pilmer and George Monbiot. If you haven't seen it you can view here:
http://www.abc.net.au/news/video/2009/12/15/2772906.htm
The only thing that I want to focus on in this question is the discussion about volcanoes that occurred. Basically, Ian Pilmer had claimed there are undersea volcanoes that we don't account for (according to him - 85%) and George Monbiot (along with Tony Jones) say this isn't true because the US Geological Survey has apparently accounted for every single one of them.
I find myself sceptical of this because as far as I am aware (and have heard over the years) humans have barely explored the world oceans. There are many hurdles that we are yet to overcome and one big one that comes to my mind (among others) is....water pressure. Now basically, what I am saying is if this is still true to this day then how has the US Geological Survey been able to reach their conclusion?
The ocean is a big place and I am sure that it and volcanoes are fields that would take many years of study. So I ain't very knowledgeable on this which is why I am pretty much asking what method has the US Geological Survey used? Could it be/is it flawed? If it is then this opens up some interesting questions. But these are the problems I am having. What methods do they use? Are they able to detect every single undersea volcano without actually having to go under the water and deal with the problems associated with that?
EDIT: To be honest, none of these answers so far are doing it for me and so I have extended the time limit.
EDIT 2: Whilst you did provide some interesting information from your links Dana, they didn't really answer anything I was asking. The 'carbon article' seems to focus more on CO2 (which isn't what I was asking for) and states many times a lack of incomplete and even uncertain knowledge in much of the area. There's mention of reliance on estimations, even allusions to underestimations. Lack of knowledge extends further in other areas it sounded like. None of these even addressed anything on the US Geological Survey or seemed to answer my question as to what method is used to detect underwater volcanoes.
EDIT 3: jim z, you also provided interesting info (even off of what Dana said) but with other things provided no sources. Whilst what was said may have truth in it, I wouldn't know. How they are able to detect the volcanoes? All this leads back to what I said in my question.