Read the site I gave respectfully, the science is still ongoing as the previous assertions are now being questioned with more recent science and research. Always great to see you GREENLEAF! No, I too assumed the same as you, I thought the effect was negligible and after reading past science studies would have agreed with you. But now I am finding that more in-depth research is starting to severely question the past science which dismissed the underwater venting and volcanic activity. They are making connection to climate change, the earth's orbital rotation and the events going on underwater that triggers the vents/volcanoes signaling major climate changes that some now are believing may have been cycles that have always existed. 


There are several recent studies coming out, as much of it was never fully studied like today in the past from what they are now gathering and bringing forward. There's much more this is but one site , they believe the earth itself triggers climate change.